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Calhoun: The NPS Institutional Archive
Theses and Dissertations Thesis Collection
1977
Determination of undrained shear strength of marine
clays by combined vane and direct shear analysis.
Foster, James Edward
University of Washington
http://hdl.handle.net/10945/18076
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MRUYIOIOXUBMRYMAimRfiAftMESCHtOl
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DETERMINATION OF UNDRAIMED SHEAR
STRENGTH OF MARINE CLAYS BY COMBINED
VANE AND DIRECT SHEAR ANALYSIS
BY
JAMES EDWARD FOSTER
'I
A thesis submitted in partial fulfillment
of the requirements for the decree of
Master of Science in Civil Engineering
University of Washington
1977
Approved by(Chairman of Supervisory Committee)
Program Authorizedto Offer Degree
Date
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own moot ummvNAVAL POSTGRADUATE SCHOOL
In presenting this thesis in partial fulfillment of
the requirements for a Master's degree at the Univer-
sity of Washington, I agree that the Library shall
make its copies freely available for inspection. I
further agree that extensive copying of this thesis
is allowable only for scholarly purposes. It is under-
stood
,
however, that any copyini? or pub lication of this
thesis fo:r commercial pur poses
,
or for financial gain,
shall not be allowed with out my wri tten permission
,
Signature
Date
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TABLE OF CONTENTS
Page
LIST OF TABLES iv
LIST OF FIGURES v
LIST OF PLATES vii
ACKNOWLEDGEMENTS viii
CHAPTER
I INTRODUCTION 1
II DISCUSSION OF SHEAR STRENGTH 5
1. Methods of Collecting andAnalyzing Data 5
2. Effects of Loading History onShear Strength 7
3. Laboratory vs. In-Situ Resultsfor Shear Strength 8
4. Theories for Shear Strength 9
III DISCUSSION OF DIRECT AND VANE SHEARAPPARATUS AND TESTS 17
. 1. Direct Shear Test 17
2. Direct Shear Apparatus 22
3. Vane Shear Test 2h
h . Vane Shear Apparatus 29
IV SAMPLES AND TEST PROCEDURE 31
1. Samples 31
1.1 Pacific Ocean Sample - KK076 31
1.2 Gulf of Mexico Sample - GM 32
1.3 Atlantic Ocean Sample - ATL 32
2. Test Procedure 33
ii
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CHAPTER
V
VI
Page
EXPERIMENTAL RESULTS AND ANALYSIS 36
1. Water Content vs. LogConsolidation Pressure 36
1.1 Sample - KK076 36
1.2 Sample - GM 37
1.3 Sample - ATL 37
1.4 Discussion of Water Content vs.Log Consolidation Pressure 37
2. Water Content vs. Log Shear Stress 38
3. "Combined" Shear Strength Analysis 38
CONCLUSIONS AND RECOMMENDATIONS 4 5
1. Conclusions 45
2. Recommendations 46
BIBLIOGRAPHY
TABLES
FIGURES
PLATES
47
49
54
107
iii
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LIST OF TABLES
TABLE Page
1 Classification of sensitivity ^9
2 Geotechnical properties of a typical corefrom deeper portions of the Gulf of Mexico 50
3 Properties of near surface samples fromthe seafloor 51
4 Soil properties vs. depth - Sample KK076 52
5 Soil properties vs. depth - Sample ATL 53
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LIST OF FIGURES
FIGURE Page
1 Soil parameters vs. depth 54
2 Cone penetrometer 55
3 Cone penetration data compared to vaneshear data 56
4 In-situ vane shear strength vs.vane penetration 57
5 Void ratio vs . log of pressure 58
6 Generalized e-log P diagram 59
7 Shear strength - deformation diagram 60
8 Shear strength diagram 60
9 Shear strength hysteresis loop 61
10 Determination of the cohesion andfriction components, C and
<J>
' 62
11 Water content vs. log consolidation pressure 63
12 Illustration and definition of terms for"combined" vane and direct shear teststrength analysis Gh
13 Types of soil shear tests 65
1*1 Types of direct shear tests 65
15 Atterberg Limits of test samples 66
16 Water content vs. log consolidationpressure - Sample KK076 67
17 Water content vs. log consolidationpressure - Sample GM 68
18 Water content vs. log consolidationpressure - Sample ATL 69
19 Water content vs. log shear strength -
Sample KKO76 70
20 Water content vs. log shear strength -
Sample GM 71
21 Water content vs. log shear strength -
Sample ATL 7?v
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FIGURE Page
22 Shear strength vs. normal stress andconsolidation pressure - Sample KK076 73
23 Shear strength vs. normal stress andconsolidation pressure - Sample GM 74
24 Shear strength vs. normal stress andconsolidation pressure - Sample ATL 75
25 "Combined" shear strength analysis -
shear stress vs. normal stress andconsolidation pressure - Sample KK076 76
26 "Combined" shear strength analysis -
shear stress vs. normal stress andconsolidation pressure - Sample GM 77
27 "Combined" shear strength analysis -
shear stress vs. normal stress andconsolidation pressure - Sample ATL 78
28 Illustration of "friction" componentof direct shear test 79
2Q Water content vs. ratio C /C, for a =0 80J v d n
30 Plasticity index vs. ratio C /C, for a =0 8lJ v d n
A-l Recording chart calibration for directshear test 82
A-2 Common area vs. displacement for directshear test ( R = 1.31 in.) 83
A-3 Common area vs. displacement for directshear test (R = 1.0 in.) 84
A-4 Recording chart calibration forvane shear test 85
A-5 - A-l4 Test Results - Sample KK076 86
A-15 - A-20 Test Results - Sample GM 96
A- 21 - A-25 Test Results - Sample ATL 102
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LIST OF PLATES
PLATE Page
1 Direct shear test apparatus 107
2 Direct shear load cell 108
3 Strain gage conditioner anddata strip recorder 109
4 Direct shear box, ring adapters,and pressure plates 110
5 Assembled modified direct shearbox and pressure plate 111
6 Checking horizontal displacementduring direct shear test 112
7 Monitoring consolidation indirect shear machine 113
8 Vane shear machine, strain gagevane torque pick-up replacement ll^J
9 Modified Wykham-Farrance vaneshear machine 115
10 Vane shear test in progresswith sample in direct shear box 116
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ACKNOWLEDGEMENTS
The author wishes to express his profound apprecia-
tion to Professor Mehmet A. Sherif, the Chairman of his
Supervisory Committee, for his dynamic and unselfish
guidance and encouragement. In addition, the author wishes
to thank the other members of his Committee, Professor
Richard H. Meese and Dr. Isao Ishibashi for their sug-
gestions and guidance. Thanks are also extended to Mr.
Bob Bea of the Shell Oil Company and Dr. Leland Kraft,
McClellan Engineers, Inc. for their assistance in ob-
taining the Gulf of Mexico sample and to Dr. Armand Silva
and Mr. Dave Calnan, University of Rhode Island for their
assistance in obtaining the Atlantic Ocean samples.
Gratitude is also extended to the U.S. Navy for having
funded my pursual of this Master of Science degree.
Finally, the author expresses his sincere gratitude
to his wife, Susan, daughter, Carrie and son, Travis for
their patience and help in the preparation of this thesis.
viii
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CHAPTER I
INTRODUCTION
With the rapid increase in offshore exploration and con-
struction in the 1970 's, the need to determine quality geotech-
nical properties of marine sediments has greatly increased.
Since the initial stages of off-shore developments in shallow
Gulf of Mexico waters in the late 19^0' s, submarine soil testing
has been required in progressively deeper water. Testing is
presently being accomplished in water depths exceeding 1000 feet
(Bhushan, et. al. ref. 3) from dynamically positioned drillships
and samples have been taken from depth exceeding 3 miles (ref.
20). As the water depths increase, the structures being construc-
ted are designed to resist larger and larger vertical and lateral
loads, amplifying the requirement for quality geotechnical pro-
perty determination for the design of their foundations. There
are no standardized procedures for obtaining geotechnical pro-
perties and there is no agreement within the off-shore design/
construction community as to what tests (in-situ or laboratory)
are the best for determining geotechnical properties. Eide (ref.
5) in his comprehensive review of applications of soil mechanics
to off-shore structures in 197^, pointed out that most of the
available drilling and sampling techniques were rather crude and
result in significant disturbance of the sample, hence results
of tests on such samples show great scatter making the selection
of design parameters very difficult.
Presently, empirical formulas are being used almost exclu-
sively for designing seafloor foundations on marine clay.
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2
McClellan (ref. 11) presented design procedures which are currently-
being utilized by McClellan Engineers, Inc. for ocean foundations.
These procedures which have been generally accepted by the pro-
fession involve equations of the follov/ing types:
Q = A(a +2C)A 1-1s m m s
where: Q = total friction capacity of a pile
X = frictional capacity coefficient
a = mean effective vertical pressure for depthof pile embedment
C = mean undrained shear strength for depth ofm pile embedment
A = surface area of embedded pile
Valent in ref. (7) presented the following equation for the
uplift resistance of an embedded plate (anchor) in cohesive soils:
Q = N C A (0.84 + 0.16 B/L) 1-2u cu
where: Q = total uplift capacity of a plate
N = uplift capacity factorcu l f J
C = undrained shear strength near the plate elevation
A = projected area of the plate
B = one-half the width of the plate
L = the length of the plate
Hermann in ref. (6) presented the following equation for
the bearing capacity of a footing on the ocean floor:
%lt Kl
Nc
C + K2 * N
yB + NqY D 1-3
where: q , . = the ultimate bearing capacity of the footing
K, ,K„ = shape coefficients
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N ,N ,N = bearing capacity factorsc ' y Q
C = cohesive strength
Y = submerged soil density
B = width or diameter of footing
D = depth of footing base below mudline
The value of C, the undrained shear strength, is the key
value in each of the above equations. There is no agreement as
to the best method for determining C. in this paper, the author
will focus on one procedure for determining undrained shear
strength of marine clays by utilizing combined vane and direct
shear tests which will provide quality, economical data from re-
latively "undisturbed" samples. Furthermore, an attempt is made
to corroborate the equipment and test procedures used by Webb
(ref. 21) and to expand his data and theory for shear strength
envelope to determine application to a general case versus a
specific case. This investigation will study the relationship
between the direct shear test and the vane shear test as deter-
mined from a combined analysis of clay samples from the Pacific
Ocean, the Gulf of Mexico and the Atlantic Ocean.
The equipment used was: a) direct shear device modified to
receive a relatively "undisturbed" marine sample, to have a re-
fined vertical loading system, and to provide electronic print-
out of data, b) vane shear device modified to provide constant
and controlled strain and electronic printout of data.
Consolidated undrained (CU) tests were conducted on samples
that were consolidated under varying normal loads in the direct
shear machine. These direct shear tests were followed imme-
diately by vane shear tests on those same samples, performed
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while the samples remained In the direct shear box. The data was
plotted and analyzed and a general theory proposed that will des-
cribe the entire strength envelope of marine clays utilizing
only two samples. Acceptance of this theory will greatly reduce
the number of samples and testing required to determine the
strength envelope of a marine clay.
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CHAPTER II
DISCUSSION OF SHEAR STRENGTH
II - 1 Methods of Collecting and Analyzing Data
For determining the shear strength of today's marine clay, the
vane shear and penetrometer tests are primarily utilized in-situ,
v:hile the vane shear and triaxial test are most often used in
the laboratory. For terrestial soils, the triaxial test is con-
sidered to provide the best results because it has better control
over stress, strain, pore pressure measurement and it does not
have a pre-determined failure plane. However, primarily due to
sampling methods, recovery and handling, the triaxial shear
strength test is not as reliable when dealing with marine soils.
In the marine environment we are forced to cope with materials
whose moisture contents are near or exceed the liquid limit
(figure 1). Historically, the direct shear test on a marine
clay has been thought to be unreliable because of unknown drain-
age conditions. However, the author feels that under controlled
conditions the direct shear test can provide reliable results.
The direct shear test utilized in conjunction with the vane
shear test will be investigated in this paper.
The cone penetration device is widely used to determine
shear strength of marine clays. There are several types of pene-
trometers, all of which basically involve transcribing the pene-
tration energy to values for shear strength. Figure 2 is repre-
sentative of a typical cone penetrometer. This method has the
distinct advantage of providing a continuous strength profile
with depth. The cone penetrometer is usually used in conjunction
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6
with a vane shear device. The vane is essentially used to
"calibrate" the penetrometer profile. Such a system is used by
the Naval Civil Engineering Laboratory (NCEL) on the DOTIPOS
(Deep-Ocean Tests in Place and Observation System) retrievable
platform. Figure 3 represents correlations resulting from this
type of combined testing.
Soil "Sensitivity" is important when considering the shear
strength of marine clays. Sensitivity is defined as the "undis-
turbed" shear strength divided by the "remolded" shear strength
(figure 4). Table 1 indicates the range of values of sensiti-
vity. Some highly sensitive clays have little or no strength
after being disturbed. There appears to be a close relationship
between liquidity index and sensitivity (Buchan, et . al . , ref.
15); sensitive clays with high moisture content have liquidity
indices much greater than one. It has been shown that abrupt
changes in moisture content bring about abrupt changes in sensi-
tivity (Buchan, et.al., ref. 15)
•
In general, shear strength and bulk density increase with
depth below the mudline, while water content and void ratio de-
crease. Table 2 gives a good indication as to the typical mag-
nitudes of shear strength values that can be expected. Shear
strengths of marine clays range from values as low as 0.1 psi
to values exceeding 5-0 psi, at water contents ranging between
30$ and 300$ (Noorany, ref. 13). Calcareous oozes indicate an
undrained shear strength of 0.5 to 2.5 psi. These values are
surprisingly low for such deep burial (^00-500 feet below mudline)
and are probably the result of a high degree of disturbance
(Noorany, ref. 13). Attempts have been made to simulate in-situ
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conditions by consolidating in a triaxial cell at effective over-
burden pressure. The results were values for strength in excess
of 10 times the undrained vane strength. The difference again
was attributed to disturbance and change in the stress system as
a result of sampling.
II - 2 Effects of Loading History on Shear Strength
Noorany (ref. 13) summarized the relationship between shear
strength and consolidation for marine sediments. There are areas
in the oceans where sediments accumulate at such a high rate
that there is not adequate time for consolidation; pore pressure
builds up, resulting in a soil that has very little strength for
great depths. These sediments are termed under-consolidated.
The area off the mouth of the Mississippi River is such a region,
having an estimated deposition of approximately 1,500,000 tons
of material daily. Shear strength values determined in 250 feet
of underconsolidated clay near the South Pass area of the Gulf
of Mexico showed little change in strength with depth and was
nearly equal to the determined cohesion of that clay (Noorany,
ref. 13). Terzaghi calculated that for an underconsolidated
marine soil, slopes of 10° could be subject to failure if that
sediment reached a depth of ^7 feet (ref. 12).
Normally consolidated clays exhibit ratios of unconsolidated
undrained shear strength, C , to effective over-burden pressure,
P', in the range of 0.1 to 0.4. This ratio for the Gulf of Mexicoo
prodeltaic clays averages 0.31- The value of shear strength pre-
viously mentioned for calcareous oozes were also representative
of normally consolidated marine clays.
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Overconsolidated and "apparently" overconsolidated clays
exhibit higher shear strengths; clays of the South Timbalier
area of the Gulf of Mexico have C values of almost 10 psi.
Table 3 shows typical values for some overconsolidated clays.
It should be noted that the C /P ' ratio looses meaning near the
mudline as P' approaches zero. Overconsolidation is usually
associated with removal of overburden, however, massive erosion
of the continental shelf or the abyssal plain is unlikely.
Figure 5 showing e-log P curves for Gulf of Mexico sediments,
indicates consolidation behavior similar to that for overcon-
solidated clays. This behavior is attributed to the cementation
brought about by the chemical alteration of the volcanic or car-
bonate fraction of the sediment.
The terms "under", "over" and "normally" consolidated, al-
through appropriate for land and shallow water soil mechanics,
are not necessarily appropriate for deep water sdeiments (Rich-
ards, ref. 15)- It is known that any factor that imparts unusual
structural strength to a soil will result in an e-log P diagram
that appears to represent an overconsolidated condition. It
has been further shown that complete remolding of samples re-
duces the consolidation curves to near straight lines (figure 6)
II - 3 Laboratory Vs. In-Situ Results for Shear Strength
Since the initial attempts at marine soils investigations
it has been known that in-situ values differ from laboratory
values despite extreme care to simulate seafloor conditions. The
reasons for these deviations and ways to correct them are the
objects of tremendous research effort. Numerous papers on this
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subject are presented each year at the Annual Offshore Technology
Conference in Texas. Some of the factors producing deviation in
laboratory vs. in-situ values were summarized by True (ref. 17)
and include the following:
1. Replacement of in-situ stress with uniform hydrostatic
effective stress.
2. Mechanical sampling disturbance; hydrostatic stresses
and soil structure are changed by disturbance from sampl-
ing, transporting, storage, trimming, and test sample
preparation. The result is decreased shear strength and
compressibility
.
3. Pore water expansion: sea water expands 0.5^/1000 m.
,
thus a sample from 3500 meters has a pore pressure ex-
pansion of approximately 2%. The result is a reduction
of effective stress, strength and compressibility.
4. Changes in pressure affect dissolved pore water gases.
5. Changes in temperature causes direct changes in stresses
and strength.
6. Changes in temperature and pressure can cause rapid de-
composition or growth of organic matter in the soil.
II - k Theories For Shear Strength
Shear strength as defined in terms of soil failure, has long
been the subject of discussion and disagreement. The develop-
ment of shear strength concepts began with Coulomb in 1776.
Since that time, complicated apparatus has been developed in
order to more fully define the elements of shear strength. For
this study, the direct shear test was combined with the vane shear
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test to determine the strength envelope. Both of these tests
generate enforced failure planes between stationary and moving
equipment or sample sections. A well-defined peak in the shear
stress versus strain curve (figure 7) is usually considered to
be the shear strength of a soil. The shape of this curve is
very much dependent on loading type, shearing rate, and drainage
conditions (Hvorslev, ref. 1).
Coulomb's first expression of soil failure criteria was:
xf
= C + of
tan (ji 2-1
Where xf
is the shear stress at failure, C is cohesion, of
is
the normal stress applied at failure, and<f>
is the angle of in-
ternal friction. Coulomb considered C and cf> to be constant for
a given soil and that simple tests could be used for their deter-
mination. Subsequent investigations have shown these parameters
to vary widely depending on such factors as initial water content,
shearing rate and anisotropy (Wu, ref. 22).
Casagrande, as well as Terzaghi, concluded that normal stress,
f , should be replaced by effective normal stress, ol where:
ol = o„ - y 2-2
with the pore water pressure, y, equal to zero in fully drained
tests. Terzaghi expressed the soil failure criteria in terms of
effective stresses as opposed to total stresses. The Terzaghi
failure criteria appears as
tf
= C + o£ tan 4>
'
2-3
where C' and<J>
' are the effective cohesion and effective angle
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of Internal friction. This function is illustrated as a part of
figure 8. The line OAC represents the shear strength line for
a normally consolidated clay with C = and 4> =<J>
'. Precon-
colidation of a clay has considerable effect on the representa-
tion of shear strength. The line BA is the shear strength curve
for a clay preconsolidated at a pressure of o' and exhibits an
angle of internal friction of <(>' . Preconsolidat ion to pressures
other than a' produce shear strength lines represented by the
dashed line parallel to BA . The significance of this is that C'
is proportional to the preconsolidation pressure a' in the fol-
lowing manner:
C = a' tan* 1 2-kp c
therefore equation 2-3 would appear as (Hvorslev, ref. 1)
t„ = 0' tan <j> ' + a ' tan <j>
' 2-5Af p
vc f r
For a normally consolidated clay, this formula can be modified
further such that
t„ = o' tan d> ' + a I tan <j>
' 2-5Bf f c i r
Hvorslev referred to this presentation as the Krey-Tiedman fail-
ure criteria. The general concept was proposed initially by
Krey and subsequently extended by Tiedman. It should be noted
that equations 2-4 and 2-5, as well as their representation in
figure 8, are based upon results of fully drained direct shear
tests on normally and overconsolidated clays. The first term
on the right side of equation 2-5B can be referred to as the
cohesion component and the second term as the friction component,
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thus the anomally of having two angles of internal friction, t
'
and tj>' , for the same clay and no cohesion for a normally consoli-
dated clay is thereby eliminated (Hvorslev, ref. 1).
Terzaghi (Wu, ref. 22) determined that the stress or loading
history of a sample affects the determined shear strength. Hvor-
slev (ref. 1) summarized this effect which is represented in
figure 9- This figure indicates different values of a' and ol.
The unloading and reloading of a sample produces the hysteresis
loop shown in figure 9- It is evident that the idealized straight
lines represented in figure 8 are actually complex curves.
The dashed line, DE, in figure 9 represents a slight double
curvature noted by several researches (V/u, ref. 22) from tests
on undisturbed samples. D represents the strength of a sample
at pressure oj, that was preconsolidated at a'. If tests are^ d ^p
performed at values of normal pressure greater than o\, the
strength line will pass to the reloading curve of the hysteresis
loop
.
Hvorslev (ref. 1) conducted exhaustive studies using direct
shear tests on Vienna and Little Belt clays in order to better
define the effect of over-consolidation. Hvorslev summarized
his results in an equation very similar to the Krey-Tiedman
formula
T f= C
e+
CT ftan
*e2 " 6
where C' and 6* are the "true cohesion" and "true angle of in-e v e &
ternal friction". Hvorslev concluded that C is a function ofe
water content only while $ ' is constant for a given soil. In
order to separate the two strength components, it is necessary
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13
to conduct tests on a series of samples having the same water
content at failure, but different effective stresses. This can
be accomplished by using the consolidation, unloading, and re-
loading technique illustrated in figure 10. It has also been
shown that the true cohesion at any water content Is proportional
to the equivalent consolidation pressure, o . In the triaxial
test, a is the consolidation pressure producing that water con-
tent in a normally consolidated sample (Bishop and Henkel, ref.
2). Only drained or consolidated-undrained tests with pore
pressure measurements can be used to evaluate the true cohesion.
Besides being difficult to determine, the parameters of the
Hvorslev failure criteria were formulated based upon drained
direct shear tests that considered only peak shear stress as
the failure strength. It is therefore questionable as to the
application of this criteria to other test results (Wu, ref. 22).
A change in void ratio or water content causes a change
in the shear strength of a clay, therefore a complete expression
of shear strength should include consolidation characteristics.
The semi-logarithmic plot of the consolidation diagram (u% vs.
Log P) of a normally consolidated clay is usually straight (Hvor-
slev, ref. 1). Figure 11 shows the consolidation diagram for a
sample consolidated normally, unloaded, and then reloaded.
As an alternative to the Hvorslev method of determining
shear strength, Webb (ref. 21) has proposed a simple theory for
determining the undrained shear strength envelope of marine
soils. He ran a series of "combined" vane and direct shear tests
on naturally occurring marine soils. A sample specimen was con-
solidated and sheared in the direct shear machine under a normal
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ll\
stress equal to that consolidation pressure. The normal load
was immediately removed and a vane shear test was run. The data
derived from one direct shear test and the subsequent vane shear
test is referred to as one "combined" shear strength plot. Be-
cause the vane shear tests are conducted at zero normal stress,
their resulting shear strength can be thought of as being a
function of "preconsolidation" pressure.
When plotting shear stress versus normal stress (direct
shear) or consolidation pressure (vane shear), Webb found the
vane shear plot to be linear over all values of consolidation
pressure. The direct shear plot was higher and roughly parallel
to the vane shear plot for a < P (preconsolidation pressure)
and for o > P the slope of the plot increased and passedn c K ^
through the origin when extended back. This last portion of the
direct shear plot is usually interpreted as representing the
strength of normally consolidated samples. These observations
of his experimental results led Webb to suggest a "combined"
analysis of shear strength that utilizes direct and vane shear
tests on only two samples to determine the complete strength en-
velope. The terms, definitions and relationships of this theory
are depicted on fig. 12. The plot of direct shear strength vs.
normal stress was referred to as the "Total Failure Stress En-
velope". The plot of vane shear strength vs. consolidation pres-
sure was termed the "Cohesion Line," since the vane test measures
only sample cohesion. The angle of slope of the cohesion line
was designated as cf> , while the angle' of slope of the normally
consolidated portion of the total failure stress envelope was
referred to as * . The value of shear stress at a equal toH n n ^
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15
zero was termed C -, . C was the value of vane shear stress at
consolidation pressure equal to zero. The difference in the
terms C, and C is referred to as AC. The value of o aboved v n
which the total failure stress envelope is linear is termed the
"apparent" precompression stress, P .
The factor that made this theory possible was the obser-
vation that the total failure stress envelope, as defined by
the direct shear test results, is rougnly parallel to the co-
hesion line for values of a less than P . As illustrated inn c
figure 12, the angle of slope of the total failure stress en-
velope is <j) for a less than P . Therefore, the entire total* c n c '
failure stress envelope can be drawn if C , , <j> , and<J>
are known.j-d ' c ' n
It follows that only two "combined" shear strength tests are
required to generate the total failure stress envelope; one test
at o and consolidation pressure equal to zero and the other atn f m
a and consolidation pressure greater than P . A preliminary
estimate of P is required to ensure that o for the second datac M n
point is greater than P . This method gives four data points;
two direct shear strengths and the two vane shear strengths, C,
and C . <j> is determined by connecting C with the vane shearv c v
strength at the higher consolidation pressure. A line is drawn
from the origin to the direct shear strength value at the higher
value of a . This enables the determination of<J>
. Finally, an n J '
line is drawn from C,
, at an angle of slope <}> , to intersect
the line drawn through the origin. The result is the total fail-
ure stress envelope that would have resulted from a series of
direct shear tests at progressively increasing values of normal
stress .
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16
Mathematical descriptions of this theory are as follows:
a) For a <P t„ = C,+o tan <j> 2-7n c f d n c
b) For o >P t _ = C, + P tan $ + (o - P ) tan <j> 2-8n c f d c en c n
c) For o > P t- = C +o tan <\> +AC+(a -P )(tan <\> -tan $ )n c f v n en c n c
2-9
V/here t„ = the maximum shear stress at failure
The purpose of this investigation will be to validate this
theory. Test apparatus and procedures similar to those used by
V/ebb will be utilized. A general set of samples will be used
to determine general applicability of the theory.
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17
CHAPTER III
DISCUSSION OF DIRECT AND VANE SHEAR APPARATUS AND TESTS
As outlined in the introduction, this study uses the direct
shear test in conjunction with the vane shear test in a combined
strength analysis of marine clays. Both tests have been subject
to criticism and praise. This chapter will outline the advan-
tages, disadvantages, apparatus, application, and the test pro-
cedure associated with both tests.
Ill - 1 Direct Shear Test
The direct shear test is one of the simplest soil strength
tests known as well as being the oldest; it was first used by
Coulomb in 1776 (Lambe and Whitman, ref. 10). The cylindrical
or triaxial shear test and the torsional shear test are the other
commonly used methods for soil shear strength determination. The
vane shear and cone penetrometer tests were previously discussed
and continue to have limited use.
The torsional shear test is more commonly used in Europe.
In this test, a cylindrical soil sample is twisted by applying
a twisting moment at the top and bottom (figure 13)- A lateral
stress can be applied to the sample if desired. During the dir-
ect shear and triaxial shear tests, the sample becomes badly de-
formed causing non-uniform stress and strain thus making the
measurement of the failure surface area difficult. The torsional
shear test has the advantage in that the cross-section remains
more nearly constant during shear (Lambe, ref. 9). This ad-
vantage is out-weighed by the fact that the shear displacements
vary with radius, promoting progressive failure of the soil
Page 60
18
sample. The use of an annular sample somewhat reduces this pro-
blem. The torsional shear test has the definite disadvantage
of requiring considerable specimen handling for test preparation
The triaxial test involves the axial loading of a cylindri-
cal sample (figure 13) that is usually encased in a rubber mem-
brane. Uniform pressure is applied using a pressure cell con-
taining the sample and surrounding fluid.
The direct shear test requires the placing of a soil sample
in a container having fixed and movable sections. The test is
performed by displacing the sections of the container relative
to each other. During this displacement, the soil is sheared
along one or more internal surfaces. The only resistance to
that shearing is provided by the soil. There are several types
of direct shear tests and apparatus with their names being de-
rived primarily by the design of the soil container or the shape
of the shear surface. These include (figure 1*0 :
1. 2-piece single shear box
2. single or double ring shear apparatus
3. annular or "punching" shear apparatus.
The annular direct shear test provides a more nearly con-
stant shear area than does the box or ring shear test, and con-
sequently, more uniform strains (Lambe, ref. 9)- The test is
more complex to perform and the specimen is more difficult to
prepare than those of the box or ring shear type of test.
In the double ring shear apparatus, the shearing force is
applied to a central, movable ring (figure 1*4). Samplers have
been designed such that their liners arc composed of continuous
close fitting rings (Lambe, ref. 9). These rings fit directly
Page 62
19
into the ring shear device. This eliminates the transfer of the
sample from the liner to the shear apparatus, as well as any
required sample trimming. This advantage is somewhat questionable
because the sampler is necessarily thick walled having a high
area ratio, A (Terzaghi and Peck, ref. 18). High area ratios
result in "disturbed" (A greater than 20£) samples, increasing
the danger of remolding and weakening the soil before testing.
Of the three direct shear tests discussed, the 2-plece
simple shear box is the most used in the United States. A basic
representation of the simple shear box appears in figure 1*J . The
soil to be tested fills the two sections of the box and is fitted
with a plate on top and bottom. The plates can be pervious or
impervious depending on the nature of the direct shear test
being conducted. Usually the lower section of the shear box is
fixed and the upper section is allowed to move. The reverse ar-
rangement is sometimes used although is is considered to give too
high values for shearing resistance because of restraint to sample
expansion (Tschebotariof f , ref. 19)- In either case, a normal
force, N, is applied to the upper plate distributing that force
over the soil surface. A lateral load, P-, is applied to the
movable section of the shear box. The direct shear test is fur-
ther designated by the manner in which loading is applied and
displacement measured. The test can be either a stress-controlled
direct shear test or a strain-controlled direct shear test.
In the case of the stress-controlled direct shear test, the
lateral force is applied in discrete increments, often by using
dead weights. Shear displacement is recorded as a function of
time until it ceases or until failure occurs. Failure is in-
Page 64
20
dicated by a rapid increase in displacement. The stress-controlled
test is preferable in those situations requiring very low rates
of loading. The load can be kept constant for any given period
of time. It is more difficult to obtain a value for ultimate
strength due to the rapid shear displacement that occurs immedia-
tely following the exceeding of the maximum shear resistance of
the soil (Lambe, ref. 9)- This test is used for most soil
mechanics applications.
The strain-controlled direct shear test is used mostly for
research (Jumikis, ref. 8), but has some practical applications.
Normally, controlled and constant strain (shear displacement) is
applied to the movable box section by means of a gear assembly
that is either manual or motorized. The force is usually de-
termined by using a calibrated proving ring and is recorded as
a function of time or displacement. This type of direct shear
test has the advantage of providing a good measurement of both
peak and ultimate shear resistance (Lambe, ref. 9)- The stress-
controlled test requires the manual regulation of loading and
is thus more difficult to conduct.
Jumikis (ref. 8) summarized the disadvantages of the dir-
ect shear test as follows:
1. The shear area in a direct shear test is constantly
changing causing unequal distribution of shear and nor-
mal stresses over the potential sliding surfaces. This
makes the stress conditions across the sample very com-
plicated .
2. The water content of saturated samples of many types
changes rapidly as the result of changes in stress.
Page 66
21
3. There is question as to the effect of the lateral re-
straint of the walls of the shear box. The stress con-
ditions produced thus do not correspond to conditions
in a foundation. The shear stress obtained by dividing
shear force by rupture area is only approximate.
k . The time required to remove the sample from the test
apparatus can effect the water content determination.
Also, the water content at the sample boundaries show
different values than the sample interior. (Hvorslev,
ref. 1).
5- The complete state of stress at any time prior to fail-
ure is unknown.
6. The majority of "undrained" tests using the direct shear
test are not completely undrained. There appears to be
no way to determine to what degree these tests approach
undrained conditions. Ultimate strength is more affected
by this unknown merely because of the longer time re-
quired to reach ultimate shearing resistance (Lambe, ref.
9).
'
The advantages of the direct shear test comprise a short but
important list, especially as it concerns marine clays.
1. The direct shear test offers a simplicity of operation
requiring less test time and sample handling.
2. The smaller height of sample used in the direct shear
test requires less drainage time. This facilitates
more rapid Q or S tests. The shear rate can be larger
than that used in the triaxial test.
3. The direct shear test requires much less sample than
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22
does the trlaxial test.
The direct shear apparatus used in this study was a strain-
controlled single shear box type. The complete apparatus ap-
pears on Plate 1.
Ill - 2 Direct Shear Apparatus
The direct shear apparatus (Plate 1) was originally designed
and built by the Department of Civil Engineering of the Univ-
ersity of Washington and was modified slightly to conform to
the requirements of this study. This system is designed to per-
form strain-controlled direct shear tests.
Shear displacement is provided by a variable-speed motor
coupled directly to a multiple output shaft gear box. This
combination is manufactured by Karol Warner, Inc., and provides
for a wide range of rotational speeds by the proper selection
of output shaft and motor speed. The output shaft is coupled to
a gearbox mounted on the direct shear test stand. This gear ar-
rangement translates the rotational motion into the transverse
motion used to provide shear displacement in the shear box. The
various output shaft and motor speeds were calibrated against
shear displacement as a function of time. The strain (shear dis-
placement) rate can be accurately controlled from 0.001 in/min.
to 0.5 in/min. (Webb, ref. 21). The gearbox offers output ro-
tational rates that increase in steps of 10. The output shaft
designated as 1/10 rotates at 1/10 the rate of the variable
speed motor. Using a motor setting of 55 and the 1/10 output
shaft, a translational displacement rate of the shear box of
0.06 in/min. was observed.
Page 70
23
The majority of commercially manufactured strain controlled
direct shear machines use calibrated proving rings to measure
the shearing force applied to the sample. The system used in
this study employs a BLH Electronics, Inc., Type U3G1 load cell
(Plate 2) between the second gear assembly and the shear box.
This load cell was calibrated using a proving ring and the
Gould strip recorder (Plate 3). The calibration refers only to
this particular load cell-strip recorder combination at the
strain gage conditioner and chart sensitivity settings speci-
fied. The calibration appearing in the appendix as figure A-l
was determined by Webb (ref. 21) and verified by the author.
The strip recorder provided for more accurate determination of
force vs. displacement. It has the added advantages of making
the recording of the test easier as well as providing an im-
mediate and permanent visual presentation of the test data.
The direct shear box is shown on Plates 4 and 5- The area
2of the shear box in its original configuration was 9 in . The
top portion of the box is fixed and the bottom is free to move.
There is a porous stone at the bottom of the lower section allow-
ing drainage. The shearing surface is 0.5 inches above this
stone. The samples used in this study have a round cross-section
Ring adapters (Plate ^) were designed to fit inside the square
shear box and accept the samples directly from their liner.
Plate 5 shows the ring adapters in place along with the vertical
pressure plate. Adapters were designed for liners with a 2.62 in
inside diameter as used to collect Pacific sample KK076 and a
2.00 in. inside diameter for the Gulf of Mexico and Atlantic
samples. The Gulf of Mexico samples were approximately 2.25 in.
Page 72
2H
In diameter and were trimmed to 2.00 in. with a thin-walled
cutter. The atlantic samples v/ere 2.00 in. in diameter.
The air pressure operated vertical loader, apparent in
Plate 1, used for conventional applications of the direct shear
test, proved inappropriate for this study. This loader did not
allow for accurate control of small values of normal load. A
simple lever arm system was designed to replace the air loader
(Plates 1, 6 and 7). The arm has a lever ratio of 10 to 1. By
knowing the cross-sectional area of the ring adapters, the de-
sired normal load was easily applied by placing the proper weights
in the tray.
The area of sample resisting shear was reduced as a function
of displacement as the test progressed. This area is easily
determined when the shear box has a rectangular or square sec-
tion. This determination was more difficult for overlapping
circular sections as was the case in this study. This area is
plotted as a function of displacement in the appendix, figure A-2
for the 2.62 in. samples and figure A-3 for the 2.00 in. samples
and was based upon the following relationship:
-1 _X_
2R90° "~* L ^ ^2R
2ttcos
2R . . _i . xA = R { ^ - sin [2cos x (^)]} 3-1
where A is the coincidental or "common" area of two overlapping
circles of radius R, as a function of displacement, X.
Ill - 3 Vane Shear Tests
Granular soils that are free draining and contain signi-
ficant amounts of water, present little problem when determining
Page 74
25
shear strength, either in the field or the laboratory. V/ith
marine clays, the foundation engineer is confronted v/ith the
problem of determining the strength of a saturated clay with
very low permeability that does not allow free drainage. The
pore pressures associated with shear stress application do not
readily dissipate in such materials. The time required for
dissipation of these pore pressures, with its accompanying in-
crease in shear resistance, is a function of the boundary con-
straints, dimensions, and consolidation characteristics of the
particular clay material.
When testing a saturated clay using the unconfined compres-
sion test or triaxial test with the minor and the intermediate
principal stresses equal to zero, the result is the <j>= con-
dition described by Terzaghi (ref. 18). The shear strength
under these conditions is described by the equation:
S = C = %q 3-2^Hu
Where S is the shear strength, C is the cohesion, and q is the
ultimate unconfined compressive strength. There are relatively
quick, uncomplicated strength tests available when the undrained
condition exists, whether in the field or the laboratory. The
test that fulfills these needs is the vane shear test. The vane
test is analogous to the Q test, if carried out rapidly enough.
The vane test, in its simplest form, consists of pushing a four
bladed vane, mounted on the end of a thin rod, into the soil
with as little disturbance as possible. The vane is rotated
and the torque required to turn the vane is recorded as a func-
tion of vane rotation. In more refined field vane shear tests
Page 76
26
the vane is pushed into the soil inside a shield and is protruded
only at the time of the test (ref. 18). Elaborate laboratory
vane devices are available that can control boundary conditions
and stress-strain rates during testing.
Investigation has shown that the soil fails along a cylin-
drical surface circumscribed by the outer vane edges. Both the
top and bottom of the vanes are included as failure surfaces
in most vane shear tests. The relationship between angular ro-
tation and torque must be known along with applied torque and
vane dimensions in order to determine shear strength. The re-
lationship is expressed by the formula:
2 3
M = it t (2gS + \-) 3-3
where M = net applied torque, x = C = q /2 = shear strength,
D = vane diameter, and H = vane height.
If the top of the vanes are not into the soil enough to
contribute to the resistance, the formula appears as:
The test and formulas make the assumption that the failure is a
right circular cylinder with a diameter equal to the vane blade
diameter, D, in which the stress distribution at maximum torque
is everywhere equal on the surface of the cylinder.
Sensitivity can be determined using the vane shear test.
The vane is rotated several times after determining the "undis-
turbed" strength and then allowed to consolidate. The test is
then repeated thus measuring "remolded" strength from which the
Page 78
27
sensitivity is determined. Values for sensitivity determined in
this manner differ from those determined if the sample is re-
molded by kneading (ref. 18).
Sibley and Yamane invented (1965) a small, convenient, hand-
held vane shear device known as the TORVANE. It has gained wide
acceptance and is widely used, both in the field and laboratory.
The vanes are pushed to their full height into the soil and tor-
que is applied by turning the upper knob until the soil fails.
The value of C is read directly from the scale on the top of the
TORVANE. Typically, the scale is calibrated so that one re-
volution of the pointer corresponds to C = 1 tsf. In spite of
several modifications, the TORVANE cannot be used accurately
on saturated clays with a q much greater than 1 tsf or on
materials that contain pebbles, sandy layers, or any other secon-
dary structure (ref. 1*0. A larger vane attachment is available
to obtain more accurate values for C less than 0.25 tsf. Also
available are miniature torque wrenches that can give torque
directly and with fair accuracy.
The TORVANE is the object of considerable criticism includ-
ing: 1) it only samples the surface of the unit, 2) there is
poor control over the rate of shear, and 3) it is not firmly
mounted, thus allowing for something other than a cylindrical
shear surface. The TORVANE should be used with some discretion
with these objections in mind. Its primary uses should be to
make preliminary estimates of shear strength, to compare mater-
ials, or to identify soils that require further testing.
More elaborate vane shear devices are available for the
laboratory. One manufactured by the Leonard Farrell and Co.,
Ltd. and another by Wykham-Farrance Engineering, Ltd. are the
Page 80
28
most commonly used. The devices operate using the same princi-
pals and assumptions, but allow for more accurate determination
of torque and vane rotation than devices such as the TORVANE
.
Torque is applied through interchangeable, calibrated springs
with different spring constants; the proper spring being deter-
mined by the soil being tested. The Wykham-Farrance machine is
available with a motor driven vane. It is this machine that was
modified for this study. The modifications will be discussed
in detail in subsequent pages.
Neil Monney (ref. 7) has recently experimented with the
vane shear test. Monney listed several serious deficiencies
with the vane shear test that include:
1. the test is not applicable to granular soils
2. the failure surface is predetermined and oriented
3. the failure surface is not a perfect cylinder
4. the confining pressure is unknown in the laboratory test
5. the vane size is not standardized
6. the drainage conditions are not known
7. the rate of shear is not standardized
Monney concerned himself with item 7- He hypothesized that since
a saturated clay behaves as a visco-elastic material, it should
exhibit an increase in strength as the shear rate is increased.
The rate of shear used by most researchers and engineers ranges
from l°/min. to 90°/min. with 6°/min. being most common. In
Monney ' s study, Wykham-Farrance machine was modified in a manner
similar to that used during this study. Saturated clay was
tested for "undisturbed" and "remolded" values over ranges of
angular strain rate up to 720°/min. and the following was ob-
Page 82
29
served
:
1. Vane shear strength varies significantly with ranges of
angular strain rate commonly used by engineers and
researchers
.
2. The shear rate should be standardized.
3- The standardized rate should be 90°/min.
These conclusions leave considerable room for discussion. It
is not apparent how different soils or vane sizes would have af-
fected the results. Values of strength determined at 90°/min.
strain rate may not be appropriate to evaluate every foundation
performance; different strain rates could be more appropriate
for different applications.
The ASTM is presently considering several vanes and test
procedures for standardization of the laboratory vane shear test
A field vane shear test using a larger vane is standardized as
ASTM £D-2 573.
Ill - H Vane Shear Apparatus
The basic vane shear apparatus used for this study was the
Wykham-Farrance, Ltd., instrument previously mentioned. This
machine was modified to transform this stress-controlled appara-
tus to a strain-controlled unit.
In its normal configuration, the above vane device has a
small one-speed motor that drives a small gear assembly at the
head of the instrument. This gear assembly is attached to the
vane through a calibrated spring. During the test a torque is
applied to the vane, the amount of which is determined by the
angular deflection of the spring which is read at the head of
Page 84
30
the instrument. The test is completed when the torque reaches
the point where the soil fails as indicated by a sudden release
of spring deflection. Uniform rate of shear is not possible
using this arrangement.
The major modification to the Wykham-Farrance machine was
the replacement of the spring with a plate mounted with strain
gages in a configuration designed to measure torque on the vane
shaft. The strain gage replacement is shown on Plate 8. The
modified vane shear device is shown on Plate 9-
The variable-speed motor and multiple output shaft gear-box
described for use with the direct shear machine has also been
adapted for use on the vane shear machine. This apparatus was
calibrated enabling the accurate selection of sustained vane ro-
tation rates that range from 0.005°/min. to 100°/min.
The strain gage torque pick-up was also connected to the
Gould strip recorder in order to get a detailed record of the
test data. The torque pick-up was calibrated by alternately
applying known values of torque and recording the movement on
the strip chart. The calibration is expressed in terms of shear
stress as a function of chart sensitivity and vane configuration
in the Appendix as figure A— -4 as determined by Webb (ref. 21)
and verified by the author.
Page 86
31
CHAPTER IV
SAMPLES AND TEST PROCEDURE
IV - 1 Samples
In order for this investigation of shear strength character-
istics of marine clays to be of a general nature, quality "undis-
turbed" samples were obtained from three areas with vastly dif-
ferent geographic location and sedimentation and loading history.
The three samples were from the Pacific Ocean, Gulf of Mexico and
the Atlantic Ocean. The samples from the Pacific Ocean were
supplied by the U.S. Naval Civil Engineering Laboratory, Port
Hueneme, California, and were collected by the Hawaii Institute
of Geophysics in late 1973- The samples from the Gulf of Mexico
were supplied by McClellan Engineers, Inc., Houston, Texas, and
were originally collected for the Shell Oil Co. The samples from
the Atlantic Ocean were supplied by the Ocean Engineering Depart-
ment, University of Rhode Island and were collected by a research
vessel from Worcester Polytechnical Institute.
IV - 1.1 Pacific Ocean Sample - KK076
This sample was from a ^0 foot core taken in water in excess
of 5000 meters in depth by a modified Ewing piston corer (ref.
20). Inside diameter of the polycarbonate core liner measured
an average of 2.62 inches. The sample was taken northeast of
the Hawaiian Islands at : Latitude 30° - 59 ' - 2*4" N
Longitude 1^9° - 50 ' - 6" W
KK076 was from an area of basaltic abyssal hills covered by a
thin layer of deep-sea, pelagic clay (reT . 20). The material
tested was from a depth in the core of ^ICWl-^28 inches. At this
Page 88
32
depth the material was a dark brown clay classified by the Uni-
fied Soil Classification System as OH (fig. 15). Table 4 sum-
marizes the soil properties of KK076 as a function of depth of
core.
IV - 1.2 Gulf of Mexico Sample - GM
This sample was taken in 167 feet of water on May 28, 1976,
near Eugene Island in the Gulf of Mexico (exact location pro-
prietary). The sample was part of a 2k inch long core taken at
30 feet below the mudline with a 2.25 in. inside diameter thin
wall push tube. The material at this depth was a soft olive-
gray clay classified by the Unified Soil Classification System
as CH (fig. 15). The following properties were observed by
McClellan Engineers, Inc., at the 30 ft. level:
Vane Strength .15 tsf with water content = 5 6 . 7 55
Liquid Limit 97$
Plastic Limit 33$
Plasticity Index 6k%
IV - 1.3 Atlantic Ocean Sample - ATL
This sample was taken in ^935 meters of water near the
Bahama Outer Ridge in the Atlantic Ocean at:
Latitude 28° - 17 ' - 5^" N
Longitude 72° - 17' - 48" W
The sample specimens were part of a 136 foot, 2.0 inch diameter
core, and were from approximately 11 meters below the mudline.
The material at this depth was a soft-olive gray clay classified
by the Unified Soil Classification System as Oil (fig. 15). Table
5 lists the geotechnical properties of ATL as a function of depth
Page 90
33
of core.
IV - 2 Test Procedure
The procedure used in this investigation consisted of sam-
ple preparation, consolidation, direct shear test and then im-
mediate removal of normal load and vane test. For each test, a
1.5 inch section of sample is cut and the remainder quickly re-
sealed and placed back under refrigeration. The direct shear ring
adapters (Plate 4) were designed to match the inside diameter of
samples KK076 and ATL, 2.62 inches to 2.00 inches respectively.
A cutter was designed to trim sample GM from approximately 2.25
inches to 2.00 inches. Filter paper is placed in J~he bottom on
the lower porous stone. The sample is pushed into the shear box
directly from the liner in the case of K076 and ATL, and from the
cutter in the case of GM . The outer portion of the shear box is
filled with water in order to keep the porous stone moist and
water is placed on the top of the sample to keep it from drying
out or sticking to the top plate. The pressure plate and lever
arm are attached and the desired normal stress is applied by add-
ing weights to the tray (Plate 6).
The sample is allowed to consolidate at the total normal
stress level overnight. A dial gage is placed (Plate 7) in order
to monitor consolidation. The shearing of the sample proceeded
after the consolidation had ceased, at a rate (i.e., 0.06 in/min)
to ensure "undrained" test conditions.
Immediately prior to shearing the sample, the locking pins
are removed from the direct shear box. The shear rate is adjusted
and the load cell voltage, chart speed, and chart sensitivity
Page 92
3 'I
selected. The shear rate chosen for this study was 0.06 in/min.
as utilized by Webb (ref. 21). The test commences after placing
a dial gage to check the horizontal displacement of the shear
box (Plate 6). The test is stopped after 0.3 inches of shear has
taken place. The pins connecting the shaft from the load cell
to the shear box (Plate 2) are removed and the zero point on the
recording chart is checked for drift. The shear box is removed
from the direct shear apparatus, the water emptied, and the box
placed under the vane shear machine for the vane shear portion
of the test. The vane is lowered into the surface of the sample
.5 inch. At this depth, the vane does not pass through the dir-
ect shear surface. This is shown schematically as follows:
Direct She;Box
Vane
~~:^lJL
Porous Stone V
— Direct ShearRing Adapters
Samule
Direct ShearFailure Surface
-Filter paper
Before starting the vane shear test, the gear box output
shaft and motor settings are changed in order to facilitate vane
shear at the same rate as the direct shear. Per Webb (ref. 21),
these rates are 7°/min. for vane shear and 0.06 in/min. for dir-
ect shear. The strain gage conditioner voltage is changed as is
Page 94
35
the chart sensitivity. The chart is zeroed on a line of the
chart and the test proceeds_ through a vane rotation of at least
30° (Plate 10). The vane is then raised out of the sample and
the zero point checked for drift.
The final item is to determine the water content of the
sample. The method used in this study is to take the water
content sample down through the direct shear failure surface
inclusive of the material sheared by the vane shear machine.
This sample is immediately weighed and placed in an oven for
drying and subsequent reweighing for water content determination
Page 96
36
CHAPTER V
EXPERIMENTAL RESULTS AND ANALYSIS
The first portion of the experimental work involved the cali-
bration of the loading and recording devices (figures A-l and
A-4) of the direct and vane shear equipment and strip recorder
setup. The primary work of this investigation was to verify the
reliability and reproducibility of the test procedures described
in Chapter IV and to run the "combined" direct and vane shear
tests and analysis on a general set of samples in order to vali-
date the theory proposed by Webb (ref. 20), as discussed in Chap-
ter II. Figures A-5 through A-25 contain the data collected
from running the "combined" vane and direct shear tests on the
three samples. Sample shear strengths are represented by:
a) water content vs. log consolidation pressure
b) water content vs. log shear strength
c) shear strength vs. normal pressure and consolidation
pressure
.
These relationships are discussed in the following paragraphs.
V - 1 Water Content vs. Log Consolidation Pressure
Immediately following completion of the "combined" direct
and vane shear tests, the water content was determined on each
specimen as described in Chapter IV. These water content values
were plotted against the log of the pressure used to consolidate
each specimen prior to the direct shear test.
V - 1.1 Sample KK076
Water content as a function of laboratory consolidation pres-
Page 98
37
sure for sample KK076 is depicted in figure 16. As anticipated
and as previously discussed, the consolidation curve for this
sample appears to be the reload portion of the curve of consoli-
dation, figure 11. The "apparent" precompression stress, P,
from this plot appears to be approximately 5-2 psi.
V - 1.2 Sample GM
Figure 17 indicates a plot of the water content of sample
GM as a function of laboratory consolidation pressure. Results
similar to those reported for sample KK076 were observed except
that the change in slope of the curve at the "apparent" P was
not as great as for sample KK076. The "apparent" ? from this
plot appears to be approximately 6.0 psi.
V - 1.3 Sample ATL
Figure 18 indicates a plot of the water content of sample
ATL as a function of laboratory consolidation. Results similar
to those reported for samples KK076 and GM were observed. The
"apparent" P^ from this plot appears to be approximately 7-2 psi
V - 1.4 Discussion of Water Content vs. Loc Consolidatio n
Pressure
The plot of water content vs. log consolidation pressure
for all three samples indicate two distinct straight line seg-
ments with a change to a steeper negative slope at the apparent
P for increasing consolidation pressure. This is the classical
indication of an over-consolidated soil.
V - 2 Water Content vs. Log Shear Strength
Figures 19, 20 and 21 summarize the results of this part of
Page 100
38
the investigation. There are both similarities and variances
among the three plots. The water content was plotted against the
log shear strength for the results obtained by both the direct
shear test and the vane shear test. The water content vs. log
direct shear strength for sample KK076 was a straight line over
the whole range of normal stresses, while this plot for samples
GM and ATL indicates two straight lines with a change of slope
at (n% = 70.4, a = 5.5 psi and w% = 159-0 or = 6.7 psi, res-
pectively. The water content vs. log vane shear strength for all
samples was a straight line over the whole range of consolidation
pressures. These plots, although not corresponding precisely
with each other, did closely approximate the observations by
Webb (ref. 21). The "apparent" P determined from this part of
the investigation was 5.5 psi and 6.7 psi for samples GM and ATL
respectively, compared with 6.0 psi and 7.2 psi as determined by
the water content versus log consolidation pressure curves.
These values compare favorably and appear to present evidence
that the test apparatus, loading procedure, data collection sys-
tem and data presentation worked as designed.
V - 3 "Combined" Shear Strength Analysis
A "combined" test consists of a direct shear test conducted
at a normal stress equal to the consolidation pressure of a
sample followed immediately by removal of normal load and a vane
shear test. Because the vane shear tests are conducted at zero
normal stress, their resulting shear strength can be thought of
as being a function of "consolidation" pressure. The data de-
rived from one direct shear test and the subsequent vane shear
Page 102
39
test is referred to as one "combined" shear strength test.
Conventional techniques for presentation of shear strength
data plot shear strength versus normal stress. The conventional
technique was modified in this presentation by the addition of
the vane shear data plotted on the same graph with shear strength
as a function of consolidation pressure. The direct shear strength
results were plotted versus normal stress. The results of the
"combined" shear strength tests on samples KK076, GM and ATL are
presented in figures 22, 23 and 2H . These figures plot shear
strength during direct shear and vane shear tests as a function
of applied normal stress, o and consolidation pressure. The
results of the strength tests shown in figures 22, 23 and 2h ex-
hibit several similarities. Above a certain value of o , then'
plot of the direct shear data appears linear and when extended
back, passes through the origin. The generally accepted inter-
pretation is that this linear portion of the curve represents
the strength of "normally" consolidated samples. Below this
value of normal stress, a change in slope of the curve is appa-
rent. These observations were evident for all three samples.
The "apparent" P determined by this part of the investi-
gation was 5-2 psi, 5-9 psi and 6.7 psi for samples KK076, GM
and ATL, respectively. A summary of "apparent" P values de-
termined by the three different test methods is as follows:
KK076 GM ATL1. Water content vs.
log consolidation pressure 5-2 psi 6.0 psi 7-2 psi
2. Water content vs.log shear strength 5.5 psi 6.7 psi
3. Shear strength vs.normal pressure 5-2 psi 5-9 psi 6.7 psi
Page 104
40
The values of "apparent" P determined experimentally are in
relatively close agreement indicating consistency in the testing
and analysis methods.
The direct shear strengths measured always exceeded the vane
shear strength values at the consolidation pressures that cor-
responded to the normal stresses at which each direct shear test
was conducted. The plots of the vane shear strength vs. con-
solidation pressure were approximately linear in the three samples
although there was some scatter of data points. The vane shear
strength plots did not exhibit the change in slope characteristic
of the direct shear strength plots. The plots of direct shear
strength, in the regions at low values ol* a , seemed to be almost
parallel with the plot of the vane shear data although the slope
of the envelope was slightly greater for the direct shear values.
Similar observations by Webb (ref. 21) led him to propose
the "combined" analysis of shear strength as described in Chapter
II and as depicted on figure 12. Only two "combined" tests are
required to determine the complete failure envelope; one test
at o and consolidation pressure eaual to zero and the other atn l
o and consolidation pressure greater than P . The proceduren * & c y
outlined in Chapter II was used to analyze the results of the
direct shear and vane shear tests on samples KK076, GM and ATL
.
The analyses are summarized in figures 25, 26 and 27. The com-
plete failure envelope was drawn for each sample using only two
"combined" shear strength tests. The remainder of the test re-
sults were plotted on the same figure for comparison. There was
reasonably good correlation between the total shear strength en-
velope and the plotted data points. As previously mentioned,
Page 106
4]
the results of this investigation seem to indicate that the dir-
ect shear line between o =0 and o = P is not exactly paralleln n c J ^
to the vane shear line in this area but is slightly steeper . Fig-
ures 22, 23 and 2k indicate the slope that best represents the
direct shear data points in the region o = to o = p for sam-^ n n c
pies KK076, GM and ATL. These figures indicate that the slope
in the portion of the direct shear envelope for a < p is higher^ ^ n c to
than(f>
obtained from the vane shear results by approximately
1.5°, 2.0°, 3.0°, respectively for samples KK076, GM and ATL.
This would seem reasonable since theoretically the vane shear
test only measures cohesion, therefore if the portion of the
direct shear line for a < P were parallel to the vane shearn c ^
line, it too, would only measure "cohesion". It is generally
accepted that since the direct shear test is run under a normal
stress that it measures both "cohesion" and "friction". Accord-
ingly, it would be expected that the slope of the direct shear
line for a < P would be greater than that of the vane shearn c °
test by the amount of the "frictional" component. Figure 28
illustrates this point. With the exception of<f> f , all the terms
of figure 28 are the same as those of Webb's theory of "combined"
analysis of shear strength as depicted on figure 12. <J> fis the
angle of the slope of the friction component of the total failure
envelope in the overconsolidated range of the plot for o < P
Therefore, from the results of this investigation, It is felt
that Webb's theory should be modified to reflect a "frictional"
component in the portion of the direct shear line for o < P .
Based on limited data, this "friction" component should be ap-
proximately 2° - 3° for $ as shown on figure 28.
Page 108
l\2
Another point that merits discussion is the fact that the
cohesion value at o =0 obtained from the direct shear test,
C , , and the vane shear test, C , are considerably different for
each of the three samples. Theoretically, these values should
be equal so that AC is zero (refer to fig. 12). It was thought
that perhaps the water content or the plasticity index might show
some correlation between C and C, because of the idea that the
geometry of the failure planes seem to be a function of water
content. Figures 29 and 30 plot the ratio of C /C , versus water
content and plasticity Index at o = for the three specimens
used in this investigation. The data is scattered and no real
correlation can be drawn except that the ratio, C /C , , is in the^ ' v d'
range 0.66 to 0.76. Another thought was that the two tests
measure shear resistance along planes orthogonal to one another
and that due to the platy shape of the clay particles the shear
resistance along the horizontal plane might differ from that
along a vertical plane. Limited testing was accomplished with
the vane test in both the vertical and horizontal directions. It
was found that the shear resistance along the horizontal plane
was actually less than that along a vertical plane which would
cause the C /C, ratio to be further divergent and increase AC.v d to
The most likely explanation of the difference between C, and C
is in the failure mechanism of both tests and how it relates to
the current theory. Presently, the shear stress of the direct
shear test result is the shear force required to move the shear
boxes relative to one another divided by the cross-sectional
area of the sample. In the vane shear test the shear stress
is taken as the torque required to turn the vane divided by the
Page 110
'13
first moment of the cylindrical area that the ends of the vanes
transcribe. In this investigation a one-inch diameter, one inch
deep vane was pushed one-half inch into the sample while running
the vane shear test. As the test was performed and the soil
failed, the vanes initially did not cut out a cylindrical sec-
tion, but tension cracks commenced propulgating away from the
ends of the vanes, and also from the ends of the vanes toward
the interior of the vane shaft. This apparently weakened the
sample so that with subsequent rotation of the vane the peak of
the shear stress versus strain curve (fig. 7), was consistently
lower by a constant amount than the direct shear line in the
region o < P .to n c
As discussed and illustrated in Chapter I, present state-
of-the-art criteria for designing marine foundations still con-
sists mainly of empirical formulas. One of the key components
of these formulas for bearing capacity, pile capacity or up-
lift capacity is the value of C, undrained shear strength. There
are many methods for determining the undrained shear strength of
a marine clay such as TORVANE, cone penetrometer, triaxial com-
pression, vane shear, direct shear or fall cone. However, each
of these tests has advantages and disadvantages, as described in
Chapter II, with no general agreement as to which is better. The
geotechnical engineer must use his own judgement, which may be
affected by availability of test equipment, magnitude of pro-
posed project, his own confidence in particular tests, etc. in
choosing the undrained shear strength tests that he will specify.
He will probably require that a combination of these methods be
used in arriving at realistic values of C. The author feels that
Page 112
by using the "combined" vane and direct shear method discussed
in this paper, reliable data will be produced with considerable
sample conservation and reduced time for testing, which makes
the method attractive from an economical standpoint.
In summary, it is felt that the "combined" vane and direct
shear analysis will provide an economical, consistent and real-
istic procedure to the geotechnical engineer for determining
the undrained shear strength of marine clays. The method is
simple, direct and does not require complicated equipment. It
is highly reproducable and provides a permanent documentation of
test results. As in most laboratory analysis, it is mandatory
that rigorous adherance to strict, consistent laboratory pro-
cedures be observed in order for the data collected to be use-
able and representative.
Page 114
'15
CHAPTER VI
CONCLUSIONS AMD RECOMMENDATIONS
VI - 1 Conclusions
The conclusions of this investigation are as follows:
1. With rigorous control and consistency of laboratory procedures,
using strain controlled testing and electronic data printout,
the tests and data resulting from the direct shear and vane
shear procedure described herein are both reliable and re-
producible from one researcher to the next.
2. With similar results on tests of clay samples from the Pacific
Ocean, Gulf o? Mexico, and the Atlantic Ocean, the "combined"
theory for "Total Failure Envelope" is a general theory that
can be used (with slight modification) for any and all marine
clays regardless of water content, deposition rate, geographic
location, water depth, etc.
3. When using the "combined" theory, the slope of the portion of
the direct shear failure envelope for a < P should be in-1 n c
creased by approximately 2° - 3° (4> f ) to more closely approxi-
mate the failure envelope in this region (see figure 28).
4. For each sample there is a constant difference between C-, and
C in the range o = to P . This difference appears to bev to n c
^a function of the differences between failure mechanisms for
the direct and vane shear tests and present theory used to
calculate shear stress in each case. The ratio of C /C,
varies from 0.66 to 0.76 indicating a consistent underestima-
tion of shear strength by the vane shear test.
5. Acceptance of the "combined" shear testing procedure will
Page 116
he
significantly reduce the number and size of sample specimens
required and the number of laboratory tests required to de-
termine the geotechnical properties of marine clays.
6. The values of "C" and "<j>" obtained from this "combined"
analysis can be easily and readily used in the present empiri-
cal formulas being utilized to determine the strength of the
ocean floor for the design of foundations for ocean structures
VI - 2 Recommendations
1. A procedure could be arranged to measure pore pressure
during the direct and vane shear tests allowing analysis of shear
strength in terras of effective normal stresses rather than total
normal stresses.
2. By using larger diameter samples and a special pressure
plate it may be possible to run the vane shear test under a nor-
mal stress rather than removing the normal stress during the
vane test. This should give much better correlation between
the direct and vane shear test results.
3. Great potential lies in the area of standardizing the
vane shear test, i.e., diameter of vane, depth of vane, depth
vane is pushed into sample and rate of rotation of vane, etc.
H . A correlation between the "combined" shear strength analy-
sis presented herein and the results of triaxial tests would be
of great interest.
Page 118
hi
BIBLIOGRAPHY
1. American Society for Testing and Materials, Research Confer -
ence on Shear Strength of Cohesive Soil , Col orado , i960
.
2. Bishop, A.W., Henkel, D.J., The Measurement of Soil Proper-ties in the Triaxial Test , London: Edward Arnold, Ltd., 1974.
3. Bhushan, K., "Resistance of Ocean Sediments to Sampler Pene-tration", Eighth Annual Offshore Technology Conference, PaperNumber. OTC 2624 , Texas, 1976.
4. Bouma, A.H., et . al.
, "Comparison of Geological and Engineer-ing Properties of Marine Sediments", Fourth Annual OffshoreTechnology Conference, Paper No., OTC~15l4 , Texas 1972.
5. Eide, 0., "Marine Soil Mechanics - Applications to North SeaOffshore Structures", Norwegian Geotechnical Institute , Pub-lication Number 103.
6. Herrman, H.G., et.al., Interim Design Guidelines for Sea-floor Footing Foundations , U.S. Navy Civil Engineering Labora-tory, Technical Report R799, October, 1973-
7- Inderbitzen, A.L., et.al., Deep Sea Sediments , New York:Plenum Press, 1974.
8. Jumikis, A.R., Soil Mechanics , New Jersey: D. Van Jostrand,Co., Inc., 1962.
9. Lambe, T.W., Soil Testing for Engineers , New York: Wiley andSons, Inc., 1951.
10. Lambe, T.W., Whitman, R.V., Soil Mechanics , New York: Wileyand Sons, Inc., 1969.
11. McClellan, B., "Design of Deep Penetration Piles for OceanStructures", Journal of the Geotechnical Engineering Division ,
Proceedings of the American Society of Civil Engineers , Volume100, Number GT7, July, 1974.
12. Monney, N.T., Submarine Slope Stability , M.S. Thesis, CivilEngineering Department, University of Washington, Seattle,1965.
13. Noorany, I., Gizienski, S.F., "Engineering Properties ofMarine Soils: A State of the Art Review", Journal of theSoil Mechanics and Foundation Division, Proceedings of theAmerican Society of Civil Engineers , Volume 96, Number 4-6,
1970.
Page 120
48
Ik. Peck, R.B., Hanson, W.E., Thornburn, T.H., Foundation Engineer' '
ing , New York: Wiley and Sons, Inc., 19 7 z*
.
15- Richards, A.F., et.al., Marine Geotechnique , Illinois: Univ-ersity of Illinois Press^ 19 6 7 .
16. Scott, R.F., Principles of Soil Mechanics , Massachusetts:Addison - Wesley Publishing Co., Inc., 196 3 -
17. Sherif, M.A., et . al.
, Proceedings: The International Sympos-ium on the Engineering Properties of Sea Floor Soils andTheir Geophysical Identification, UNESCO, National ScienceFoundation, University of Washington, Seattle, 1971-
18. Terzaghi, K., Peck, R.W., Soil Mechanics in Engineering Prac -
tice , New York: Wiley and Sons , Inc.
, 1967
.
19. Tschebotariof f , G.P., Foundations, Retaining and EarthStructures , 2nd Ed., New York: McGraw - Hill Book Company,1973-
20. U.S. Naval Civil Engineering Laboratory, "Geotechnical Prop-erties of the Deep Sea Floor, Northeast Pacific", addendum toMarine Geology of a Region on the Northwest Pacific , Califor-nia, 197^.
21. Webb, M.S., Combined Vane and Direct Shear Strength Analysisof Naturally Occurring Marine Soils , M.S. Thesis, Civil Engi-neering Department, University of Washington, Seattle, 1976.
22. Wu, Ming-Jiun, Dynamic Properties of Overconsolidated SeattleClays , Ph.D. Dissertation, Civil Engineering Department,University of Washington, Seattle, 1972.
Page 122
49
Description SensitivityPercentage of StrengthLost on Refolding
Insensitive
Slightly sensitive
Mediuc sensitive
Yery sensitive
Slightly quick
Hediun quick
Very quick
Less then 1
1-2*
k - 8
e - 16 •
16 - 32
Greater than 32
- 50
50 - 75
75 - 87.5
67.5 - 93.8
93.8 - 96.9
Creater than 96.9
Table 1 Classification of sensitivity(Aftcr Buchan, ct al , reference 15
P9. 72).
Page 124
50
Shear Bulk Water .
Depth in Strength Void Density,(cy/cA l)
Content SpecificCore (en) ( PS F ) Ratio K dry v/t. 1 Gravitv
20 45 3.92 1.361 141 2.7740 57 3.58 1.375 132 2.72
. 60 53 3-21 1.407 118 2.71. 80 55 3.32 1.390 124 2.68100
. ^3 3.11 1.411 116 2.69120 77 3.29 1.392 123 2.68140 53 3.20 - 1.409 . 118 2.711*0 70 3.18 1.400 119 2.67l8o 75 3.03 1.418 113 2.68200 93 . 2.82 1.442 '. 105 2.69220 113 3.02 1.410 114 - 2.65240 .120 2.83 1.428 107 2.64260 143 2.98 1.434 109 2.72270 127 3.02 1.425 112 2;71310 130 2.76 3.456 • 102 2.71320 125
•
2.80 1.444 104 . 2.63340 133 2.85 1.462 103 2.77360 110 2.81 1.466 101 2.77
•375 135 2.77 I.458 102 2.734oo 143 2.73 1.466 100 2.73420 . 157 2.60 1.479 95 2.72kkO 157 2.54 1.483 •93 2.73480 175 2.57 1.500 92 ' 2.78500 180 2.55 1.495 93 2.76520 197 2.61 I.470 97 2.7054o 195 2.53 1.494 92 2.74560 230 2.47 1.495 91 2.72600 225 • 2.42 1.510 . 88 2.74620 220 2.30 1.526 84 2.7364o 240 • 2.36 I.526 85- 2.76660 217 . 2.31 1.523 85 .. 2.73680 253 2.38 1.525 86 2.77720 240 2.29 1.523 84 .2.7474o 267 2.26 1.534 82 2.74760 247 2.20 1.5 i(
. 81 2.73-800 273 2.31 1.523 85 2.7386o 277 2.38 I.506 88 2.71
Table 2 Geotechnical properties of a typical core from deeper portions ofthe Gulf of Mexico(After Bouma, reference H pg. 32).
Page 126
51
A. * l«Estimated
LocationSamplenu rn be r
Depth,
In
feel
P <Irl
kllcjr2ms
p-er
tquare
centimeter
Pc <*
kilograms
per
square
centimeter
CjPo <=c
C„, In
square
centimeters
per second
(1) (2) (3) (4) (5) (6) (7) (8)
Mediterranean A-D! 3.1 0.C5 0.07 1.2 0.41 4 x 10-<
Mediterranean D-83 0.5 0.02 0.04 2.6 0.34 2 x 10-*
Mediterranean B-87 1.6 0.03 0.15 2 0.34 1.5 x 10"'
. Forth Atlantic C-15 2.1 0.045 0.15 1.5 0.36 1.5 x 10-'
Forth Atlantic C-I3 2.1 0.04 0.16 1 0.55 6 x l0-<Forth Atlantic COO 1.1 0.02 0.2 2 0.59 —West Atlantic D-lp 6 0.10 0.2 1 0.75 —Vest Atlantic F-6 5.1 0.10 0.15 0.4 0.63 1 x 10-'
„Wes! Atlantic F- 11 4.8 C.05 0.2 0.7 0.83 8 x 10~«
V.'cf.t Atlantic G-6 T..5 0.03 0.05 1.2 1.4 ex io—«
Easl Pacific I-KACA 0.5 0.CC5 0.09 — 0.77 —Easl Pacific J-29 — 0.005 0.08 .— " 0.9 * '*
Tcrm/^J » the effective overburden prcssjrc; f e« the estimated prcccnsotldatlcn pres-
rurt based en Casacrandc method; Ct,B the ur.dralncd shear strength, In Migrans per
f^uarc centimeter; C(« compression Index; and C r coefficient of consolidation.
Tabic 3 Properties of near surface samples from the sea floor (After Noorany,reference 13 pg. 1705).
Page 128
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Page 134
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Coblo
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Figure 2 Cone penetrometer
Page 136
56
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L<it f?;» Unit Cent lea J
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Page 138
57
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Page 140
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Fi re 5 Void ratio vs. log of pressure(After Bryant, et al, reference 15
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Page 142
59
V-<
LABORATORYSEVERELYDISTURBED
LABORATORY REBOUND(ALSO TO O
LABORATORYSLIGHTLYDISTURBED
LOO PRESSURE
Figure 6 Generalized e-log P diagram(After Richards, reference 15.' pg. 104)
Page 144
Peak shear stress t
60
Deformation or Strain
Figure 7 Shear strength - deformation diagr?m.
Figure 8 Shear strength diagram(After Hvdrslev, reference 1, pg. 175)
Page 146
61
+->
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CO
OJJZto
Simple Overconsolidation(Rebound Curve) ^^
Normal Stress
Figure 9 Shear strength hysteresis loop(After Hvorslcv, reference 1 pg. 175)
Page 148
62
Normal Stress, a I
Figure 10 Determination of the cohesion and friction components, C' and<>• (After Mvorslev, reference i pg. 203).
Page 150
63
+->
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Virgin Curve
Rebound
Log Consolidation Pressure
Figure IX 'Water Content vs. log consolidation pressure(After Hvorslev,
reference 1, pg. 196).
Page 152
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Page 154
A~->
Cylindrical Compression"Triaxial Shear"
Torsional Shear
65
Figure 13 Types of soil shear tests
V/AWWW- V//\. ,J'V/'<V>*'
Tv/o-piece Single Shear Box
i
Annular or "Punching" Shear Ring Shear
Figure 14 Types of direct shear tests.
Page 156
66
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68
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Water Content, W, (%)
Figure 17 Water content vs. log consolidationpressure - Sample GM
Page 162
69
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Water Content, W, (%)
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Figure 18 Water content vs. log consolidation pressureSample ATL
Page 164
70
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Page 166
71
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82
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10 20 30
Chart Divisions
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Calibration determined for:
1. BLH Electronics, Inc. Load Cell, Type U3G1
2. Strain Gage Conditioner = 20 volts
3. Chart Sensitivity = 10 mv/division
Figure A-l. Recording chart calibration for djrect shear test.
Page 190
83
0.2 0.3 0.4
Displacement, X, (in)
0.5
General Equation:
Common Area = R
"ircos"1
^-)sin
90v
2cos-ipL
Figure A-2. Common area vs. displacement for direct shear test.
Page 192
84
C\J
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Displacement, X, (in.)
General Equation:
-1(—-)
Common Area = R2
{
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Figure A-3"1
~
Common Area vs. displacement for directshear test (R = 1.0 in.)
Page 194
.G
I-
4->
o
llote: Calibration applies for strain qocjc
conditioner voltaee of 6 volts.
o 2
iruu 400 . 600
Voltage (mv)
for top of vana net in soil;
H12
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3
/
r - Shear Stress (psi) M s Moment en Vane Shaft (in- lb)
II *• Vane Height (in) D = Vane Diameter (in)
figure A- 1; Recording chart calibration for vane shear test.
Page 196
86
Date DO/S/76 Tested by: J. For, tor
Sample if:KK °7° Water depth: ?QOO+m Sample depth: + 36'
• 25 mm/rnin Chart speed 25 mm/mi
n
20 v Signal Conditioner G v
10 mv Sensitivity 20 mv
O.o psi Normal Stress, Consolidation Pressure q.O psi
1.57 psi rmax
1.16 psi
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Water Content (S): 265.1
1 mm = 1.5 lb. 1 mm = .11 psi
10
20
30
40
en<u"O
co
to
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Figure A- 5 Test Results - Sample KKO76
Page 198
87
Dale: 10/6/76 Tested by: J. Poster
Sample //.'KK076 Water depth: ^'ooo+m Sample depth: ± 36'
• 25 rnm/min Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
1.1(6 psi Normal Stress, Consolidation Pressure l.h/psi
3.82 P si rm.ax 1.^ P si
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Direct Shear Vane Shear
Water Content [%): 255 .8
1 mm - 1.5 lb. 1 mm = .11 psi
10
20
30
40
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Figure A- 6 Test Results - Sample KKO76
Page 200
88
Date: 10 /7/76 Tested by: j. For . tor
Sample H'yyOIG Water depth :c;ooCH- m Sample depth:-:- 3^1
25 mm/mi
n
Chart speed 25 mm/mi n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
?.n P si Normal Stress, Consolidation Pressure 2 -JS1
1.97 P s "> Tmax 1.39 psi
c
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0.1
0.2
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Water Content (Z): 252.5
1 mm = 1.5 lb. 1 mm = .11 psi
10
20
30
40
en
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Figure A- 7 Test Results - Sample KKO76
Page 202
89
Date: 10/8/76 Tested by: j. Footer
Sample ^KK076 ^'a ^ er depth: i^000+m^amP^ e depth: ± 3^1
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
I4..0 psi Normal Stress, Consolidation Pressure U. . psi
2.1;2 psi Tmax 1.95 Psi
4->
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s-
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10
20
30
40
cr>
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Figure A- 8 Test Results - Sample KKO76
Page 204
qn
Date: 10/9/76 Tested by:fl . Pofiter
Sample //:j<K076' Water depth: ^Q 00+:,,Sample depth: ± 5 ,
25 mm/mi
n
Chart speed 25 mrn/min
20 v Signal Conditioner G v
10 mv Sensitivity 20 mv
5.0 psi Normal Stress, Consolidation Pressure 5.0 psi
2.89 P si Tmax 2.20 P si
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to
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0.2
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1 mm = 1.5 lb. 1 mm = .11 psi
10
20
30
40
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Figure A- 9 Test Results - Sample KK0?6
Page 206
91
Date: ] 0/11/76 Tested by: j, ^storSample 'I'v^otS
^'a ter depth :-;ooo+rn Sample depth: ± -^i
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
6.0 psi Normal Stress, Consolidation Pressure 6.0 psi
3.31 Psi Tnax 2.75 psi
cr
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" :-•":--"!- r*«l'.::\. 1
. . : .:-. t..-
.• ":Z':\::
::: j;: .
1
f::.;f. ;:.: .;.;::. -'}--
- '
- !'
l::\[
- y
]-
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::
L:.i-;
'
CL i-i --
I • ; " '
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|:iii!
:
i
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: nf.u j- i
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;..;.; i . i -i •; i 1
;
i i
• hi J
Direct Shear Vane Shear
Water Content (%): 239.0
1 mm a 1.5 lb. 1 mm = .11 psi
10
20
enCD-o
cron—+->
<o+Jocr:
CJcr
30
40
Figure A- 10 Test Results - Sample KKO76
Page 208
92
Dale: 10/12/76 Tested by: j, pos tor
Sample //: j<kq76 ^a ter depth: ^000+m Sample depth: t 36'
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
8.0 psi Normal Stress, Consolidation Pressure psi
h.la= psil
rmax 2.81 psi
o
OJ
to
0.1
0.2
Shear Stress
-s\.-: \
"1:::::•:':: :'
:::;:. \
\: 1
:::
\ : .: :::
':"": ]
'
1
:i
:
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::: :i::
: :-:::::
:
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:
: .
:::::. :. :.-.-_ .-;::::: ;:.
:. :::.... : :::
:
;;••"-::
:'~
T:
:
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J :
:::.;.: :: :.. :
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. M::;;:: :;:.:: r .:..::
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i.;-; :
;::
;
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O
It
CU4->
s-
to
d)
>•f—
crUJ
Shear Stress
-i—f—
N
I ;";.";_'
\- -
• \
• V;-i T^;: ;
:
:nf:i:::\
; V
_. .
:.~~=Hr.;|;:-:; \
.
-. :"-::':"£
1
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:: ••;;:: 1
Livs^;1
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L:r :
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•-
:
: j :l:::
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i ;
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; :: - :
;
: l :•".!
:
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: '.-!•;j;:l-
:
!-:-:;!i: 1 : \
[ :• \-: I ; I
: . i•• :
;
• :' '
!:. "!: |
:
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::.[:..j.:: ;
N
i
' ! : ..U ...
-
Direct Shear Vane Shear
Water Content (%): 230. s
1 nun = 1.5 lb. 1 mm - .11 psi
10
20
30
40
CD
o4->
fU*->
Oa:
&c
Figure A- 11 Test Results - Sample KKO76
Page 210
93
Date: 10/1V76 Tested by: Jg Vo , t ,, v
Sample i/:kK07o Water depth: £003+m Sample depth: t 36'
25 nim/min Chart speed 25 mm/mi
n
20 v Signal Conditioner G v
10 mv Sensitivity 20 mv
10.0 psi Normal Stress, Consolidation Pressure 10.0 psi
5-t8 psi Tmax 3.1U psi
+>rroECJor—O.
$-rsCJ-CCO
0.1
0.2
Shear Stress
^"»v i""i
\
\
V —
.
:--.: I
:
ri i 1
: \
: /:. I::-i
......: 1.: : : -
:.:-!.::.:
- >
:
:. : .:: :.r j : :
p. -
J •-
': ;
:
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-.—
:
; ;
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: : !..':- .
''.
!'.
;;'::•:
| :
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': : : . :
i : : : :
•
I'
cE
O
II
CJ+->
rcJ
Cd
U(0CJ
CO
4->
CJ
>
cr
Shear Stress
: !:::r-. : 1
10
20
30
Direct Shear Vane Shear
Water Content (%); 222.5
1 mm = 1.5 lb. 1 mm K .11 psi
40
eno*u
co•f—
<o+->
Oo;
CJ
>•
Figure A- 12 Test Results - Sample KK076
Page 212
Datc: m/ii,/76 ^stcd by:fT _
,,_ tr;r
Sample ^KK076 Water depth:5O0O+m Sample depth: * 36'
• 25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
30 mv Sensitivity 20 mv
12.0 psi Normal Stress, Consolidation Pressure 12.0 psi
6.39 P si Tmax 3.2£ Psi
troE<L>
O
a.to
S-r3
to
0.1
0.2
Shear S
•
tress
\
:.i- :-: =
:: :
:.'.
'. !
: ::': 7::'
:: ::
: v :..:;;.. ;'
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:
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<
: " '!.
:-
[ ::-\\: )::: 1 :
..
:
:"^L-^• -
:
*r::.;::;.:..:: ;.| :.:.
:• - [-- }-_.:
: ;l : :• i.;-.
...:.'::
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: :
. -... - i
L± _j
o•o
II
+J
S-.
raoto
<->
c:GJ
>
o*UJ
Shear Stress
j--r|--:-?; :-;V- !-:.:.:
J
1
\ 1
\
I—
—
—
-
,-: ;;:i:;
\-----
: ::::: ::
i \
j \
_- -- - i \ ;
i \
3 ;Ui
-'." \
\
\
\
: : ]\'i
-
I 1
:
i
.J.r 1 *i
: : ; i i
' I
! !•
;
i
'
i 1
; t i
ji !
i
Direct Shear Vane Shear
Water Content {%): 218.9
1 mm = 1 . 5 1 b
.
1 mm = . 1 1 ps i
10
20
30
40
CDC)-0
cro4->
O
0.)
rro
Figure A- 13 Test Results - Sample KKO76
Page 214
Q^
Date: 10/1 S/7 6 Tested by:>T m poster
Sample //: i<j'076' Water depth: £00C+rrjSample depth: + 36'
25 mm/mi
n
Chart speed 20 mm/niin
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
l),.0P si Normal Stress, Consolidation Pressure i;i,o?si
7.30 P s i rmax h.07 P si
QJEOiu
l/V
s-
QJ
to
0.1
0.2
Shear Stress
A.: :-:)
I \ "
:
. .:.:
. . jr.:
; ;;;•:;-;;
: : ; - :
:
- :
: J
i;-.;.: ;!..;.
' 1:.':: :
: :
1
1 1
: ....:. • '
!
: .? ..;;:? :;:".|-:-:::
• ;::::; .:.;.
: .1 .:;: .[...
.
'...".''1
E
e3o
11
OJ
res
i-
Osz</)
c:cjr—
>•r-
rjcrUJ
:.:.:: A" i
l__l_;_j—;__
' : .
. ;. . i ;.-;: ::j -
•;
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;
...
:....
; ; l_ j—
Shear Stress
s ::
i
:
!
: : 1 \
V
\:
\: ."::.
: !
:
:
' :--.: ::: -i
;
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i \1 \
: ::-:;: i~r •— \
\
. -
\
-;
'
;
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;
. . \ .
:•- ..; :-:: "''-''"'
'' \
'
\
. ;
: riiiLil" '
' I \
: . ;--::;: r
! ; : :. : . |
: : ;::: i [" "i I
; i. ; ; ;
1
L ..l-.-ii-J—J.- -!•--•j
10
20
30
Direct Shear Vane Shear
Water Content {%): 213-3
1 mm = 1.5 lb. 1 mm * .11 psi
40
QJX>
rro•1—
+j10*Jocc
QJ
C
Figure A- 3.I4. Test Results - Sample KKO76
Page 216
96
Date: 10/18/76 Tested by: j, poster
Sample ii: ay{
Water depth: (j\ Sample depth: ± -^ i
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
0.0 psi K'ormal Stress, Consolidation Pressure 0.0 psi
2.26 Psi Tmax 1.60 P S1
'
c•f—
c
or—Q.10
$-
OJ
to
0.1
0.2
Shear Stress
1
: :
:
!
:'
: ;'
,
' : ... ....:
1
:: : :~:_: .:::;j
:
;;:
;
:
:
"
1
:-^#l.::^:;;:: :! !
;: ; ;,-:.:(
!
-;::;-:!
:z_.i::;:....:
E
10o*o
n
o*oC£
J-C3CD
tO
4->
Co
>ncrUJ
Shear Stress
l ''
1
i ; .'; . . 1
.
;:: : :
''
:j'
:
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;i:v!;;-;!:
\-—~—
'.'. !
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•"
.:;
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y : 1 '::;:::
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-;. ; :i.fe
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;
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.
:
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;
: ; 'i
1:;:!:;::
i
.... 1
I":-:! !
.!.
Direct Shear Vane Shear
Water Content (%): 75-2
1 mm e 1.5 lb. 1 mm = .11 psi
10
20
30
40
CJ*o
cro
o+->
o
OJr.
Figure A- 15 Test Pxesults - Sample OM
Page 218
97
Date: 10/19/76 Tested by: j. Foster
Sample if: ( ^- Water depth: -,>.n\ Sample depth: .L -> q 1
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
3.0 psi Normal Stress, Consolidation Pressure 3.0 psi
2.76 Rsi Xmax I.87 psi
+->
CJECDo
•
—
CLCO
nCD
to
0.1
0.2
Shear S tress
• j ;J ;
•
'.'-',-•
1
I
L1
'
-:: ; :
::: .:.:
;
.
;
:-:::::-;_i
y:
:{~:^-\
'.::"-'
'
i
•
.::: . : :
.•
:::::
:; : :
:
|
\,.::vY: ::.:::.\
-: L'::: :
:::.. :: ::.::::
1
' L
y\:i:-V< I
'^I :
l.\,
1 . :.:. :
;
:::i;;:
'i:J
! _:;. | 1
, - ,
— . : : :. !
MM
•t—
o
II
cu4->
C5Ct
J-«oCD.cCO
«->
c:CD
>•t—
crUJ
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!.'.'! '.'.
:-.;;:!. ,L(.
; :.:'.:: ;-\ \
~.. I. T "—"T
™
U MiM I Li±i
LLi_L_l -. .J_iJ
_ Li;.!.... J _j__LJ
10
20
30
Direct Shear Vane Shear
Water Content [%): 73.4
1 mm = 1.5 lb. 1 mm = .11 psi
40
eno•o
c:o
+->
occ
CD
o
Figure A- 16 Test Results - Sample GM
Page 220
98
Date: io/P. 1/7 J,Tested by: J. J•'0 ster
Sample //: r»i Wciter depth: 1.671 Sample depth: f • 3 '
25 mrn/min Chart speed 25 mm/ mi
n
20 v Signal Conditioner 6 v
3 mv Sensitivity 20 mv
h'S psi Normal Stress, Consolidation Pressure h.Spsi
3.26 psi Tmax 1.93 P s i
c
o
CO
0.1
0.2
Shear Stress
- : : 1
— ' r -i
: ;...:;
!'; :
:
.
:
:
\r::\"
:
; :" \
•
;,..:_:: --
. . ' .. : : .
:
-i
-:•!
'-:.:
. -: .:. ;
:
::-.;!
- ; :-;:
:; !
-:
: : :-: :.-..1
:
-t - •
:r;:: :
;:.-| .:
:: :.".". [•-
... \ ::: A-:
: .: / ;; _: L
. -
:-:: \ :! i". 1 !
"' :
1
: :. ; :. ,
h : : IT. i __j"
! : : i
:'
: . :
^•
; ; i
e5o
if
CJ+->
i-roOJC(/>
4->
COr—
>•i—
crUJ
Shear Stress
;——
—
-.—•-- N.
——
i
: \:•::
-l
:
-"i
---
; . ::
::: - r.: . —
—
-^0! ;
: : I
'..[". I
:__.
:
:
:
:i : :;• i 1
:
'i:;:
;!:::
;j
:
: t; 1
\ ! _j. "i :
:- \
• -
.-•:'::::-|
l.':':!
: :;: :.; : j :.: :.: ::.,.— ......
... ........:::1
:.:':
:
:!-
i
:i :
; ;; ;
.•.'.;:••::
i
;;i
.
; .1 : i:-!: !-! •
!
' i.\ •
i S i' ! !
i
!
1 i i :.j
i
!
t J-iJ
Direct Shear Vane Shear
Water Content (£): 71.1
1 mm a 1.5 lb. 1 mm = .11 psi
10
20
30
40
enCJ*o
co
•«
—
4->
rj+->
Occ
c:
>
Figure A- 1? Test Results - Sample GM
Page 222
99
Date: 10/22/76 Tested by: J. Fester
Sample H: r>M Water depth: 167' Sample depth: ± 30'
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
6.0 psi Normal Stress, Consolidation Pressure 6.0 psi
3.76 Psi Tmax 2Ji8 psi
4->
O
onr—CLCO
10
0.1
0.2
Shear S tress
1 .
—'
•-!
: -
i
:
:!i
:"'•• '
:
s.
\
."r:;~:~:j
1
:
::?;-:
;.:.:.[|— -- -
: ::.'._ :: ::.
:-i!;.:i^ - ;
- !.:1
:.. -': _ 1
::;: :_i
v ::!i:~ :
:: -\
-- ::•.
:
.::::
: ":::
:
": . . : -
;:.;.-;7-;
• ::: : ::.:::; ::1
: . i
"
i !
'
; ! : : : i
'..''. '.
!
: : i : i
i
1
L _| ;
-j \
'
. : : : 1
1
: : i
c•r-
E
O
II
+->
CC
Shear Stress
f--:'~'j
:
:
;": ;'
.
—:—'- >s._
:=:,-::::h i
::-:•:::.:
1
.:.:::.-;::-- -:1
.., -.i—
i
:- ;::: :. :.':
'
!_j :'.::' :;
::;::: ::: :!:::r~-':::: :
:::: : : ::::.::
•.:; :r; I..-
: .:: ;: !.:: r!,,! : i .
M~frJ
Direct Shear Vane Shear
Water Content {%): 69.5
1 mm = 1.5 lb. 1 mm = .11 psi
10
20
30
40
enOJX>
o
<3+->
OCC
Oc
Figure A- IB Test Results - Sample OM
Page 224
100
Dale: 10/26/76 Tested by: J. Poster
Sample //: GM Water depth: 167 ' Sample depth: t 30'
• 25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
9.0 Psi Normal Stress, Consolidation Pressure 9.0 psi
5.02 psi Tmax 2.93 psi
-pc:OJBGJU
cj
CO
0.1
0.2
Shear Stress Shear Stress
i { ;1
: ; i :
- -'
;
i\
! \
1
; : -..: .:.:. \ \
- . 1 - -- 1
1 \
:-:1
J
-•:!
:'::
"- -''-\-
:
."
'. . 1
v.
: : . . : -..
: :-J:-!
:
i---:i-.-i 1 -:
t
-::=•
--1-;
: : ! __
•r—
E
O•o
II
o
cc
u<3CJ-CCO
+->
c:QJr—
>rjcrUJ
r--v-"-l - - -;-——• ;—
:LSsJ
j\. : : : t \
V:;
1 . \
! \
\
:
:-:: ! \
;£-(: :\
f• 1
! \
.-: p -•-.:.
J
; :Z3 ;
f: : i :
' :|
::r'ix|^:;;j
: ..
::"- ;
i::;: .:-:..
:"-""'-i -
_;;-••: ;
/
^:L -:'
:
:
:
m ^:
:
Li_;_•
44-144_—
i
10
20
30
Direct Shear Vane Shear
Water Content {%): 66.3
1 mm = 1.5.1b. 1 mm .11 psi
40
enOJ*o
c:o•r—4->
cj4->
Oor
OJcr3>
Figure A- 19 Test Results - Sample GK
Page 226
101
Dale: 10/20/76 Tested by: J. Foster
Sample if: OU Water depth: 16?' Sample depth:* 30'
• 25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner G v
10 rnv Sensitivity 20 mv
12.0 psi Normal Stress, Consolidation Pressure 12.0 psi
6.61; psi Tmax 3-30 psi
CojEgjo
GJ
to
0.1
0.2
Shear Stress
y
\
|\A
-•: -:.H A •;-;..
:!
- i .
\ h
•::-:::::.: | :
J:
j .. . 1
: : : ; I
——i
—
'-."Pj-^M : I
.. .... . ... 1
::: -;
::i{: ;.
: ::..::::;;:
1
. ::
:.::::. ::-:i:::: :
, .V:
:.::
,:-;|; :
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i -:-:i-;»j;~:;| :. .
:
:::
::::":| ~:v.: :
. ::'.': :": n 'v
\i ...:
'
; J. .':
• -
"' ista: :
i . 1 :
1
-H_j_4 ..:
Shear Stress
•t—
Ec:
too
I!
CJ4->
ft$
*-fOO•CCO
4->
COr—CO>
crUJ
10
20
enCJ-O
cro•r—
fO+->
oai
CJ
n
30
Direct Shear Vane Shear
Water Content {%): 6k .0
1 mm s 1.5 lb. 1 mm = .11 psi
40
Figure A- 20 Test Results - Sample OM
Page 228
102
Dale: 11/15/76 Tested by: J. Poster
Sample if: ,\TL Water depth: ij.93 5n Sample depth: ± 11m
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
0.0 psi Normal Stress, Consolidation Pressure 0.0 psi
2.01 psi Tmax,
1.32 psi
troEau«3e—CXCO
CO
0.1
0.2
Shear Stress-
;; ' r;
":: :" ; -:-!
•
:.: : -
; :-i:':.:\
: ~.-:::: i
I—--C
:;::-:: E-..:.-, -
- •r—
e>
.
II,
4cj
• ~~:--:- 4->
0J
:: '::' :rr
: : ".: :
.
:
::::: ;""-:"
: H - ; J --=
:
; :."
: . -.:„:..1 ! .;! 1- CO
:~::::m~ ;: :"i
cCJ
:! 2 -:!-=: r.::~:::: ---: ::3
r3>•t—
crUJ
Shear Stress
'
f: /
1 r:r-:
n ::r-: ::. -: ::
1 .. . - . .
-:: I."
'.'
r:-: y:\
1
.
".! .
*n .
.
"
"~
1 r
!
1 2 "; 22
! .:: -.:
_2L|
1
ftps !r.;;
10
20
30
Direct Shear Vane Shear
Water Content (£): 167.7
1 mm = 1.5 lb. 1 nun = .11 psi
40
C7>OJ*o
no
Oa:
OJ$=
Figure A- 21 Test Results - Sample ATL
Page 230
103
Date: 11/18/7 6 Tested by: J . Poster
Sample //: A7L Water depth :i;93£ rn Sample depth: ± lira
25 mm/rnin Chart speed 25 mm/mi
n
20 v Signal Conditioner G v
10 mv Sensitivity 20 mv
3.0 psi f<orrr. al Stress, Consolidation Pressure 3.0 psi
2.51 psi Triax 1.65 psi
4->
trQJ
QJOa
1
—
a.to
OJ
to
0.1
0.2
Shea; : : ::.
r Stress
; \:
; .
:j
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:."_:
:
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r^
).: .: _._:.:. .::".."V."
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:
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- ———:—:
i
. . . :_:;;
i~ 1 :
•;-!-
i
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l ::.-.:i
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-: : I
1
: :
J:::
r '•
:: "N -:::
.: -: 1
t
YC ::.-
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!
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:
: : :
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i
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.:..; '.::. l-:: :.L..i;_ :._.- !
o
11
QJ«->
ct:
$-raQJJCCO
4->
c:QJ
>•I—rscr
Shear Stress
VLIL A. i
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ij
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i' -i
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10
20
30
Direct Shear Vane Shear
l/atcr Content {%): 163.^
1 mm = 1.5 lb. 1 mm = .11 psi
40
OJ-o
o•I
—
«oo;
QJcr
>
Figure A- 22 Test Results - Sample aTL
Page 232
] O'l
Date: ] 1/16/76 Tested by: J . Poster
Sample ii: ;,y r ,Water depth:
j, 93^ ro
Sample depth: t ] -) m
25 mm/mi
n
Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
6.0 psi Norma 1 Stress, Consolidation Pressure 6.0 psi
01 psi Tmax 1.82 psi
trCJEU
'o.to
QJ
CO
0.1
0.2
Shear S-
tress
L^. .:. ; .;
:
:'.':' '.':
>
':•.. J: f: - I /: :... ::; ..::.. : ::.| :
;_.:;:-.:. -:-'L:
'..
". _ . !-'.
. - !
[
:-
1 ^\:\J; -- -
: . :- -: :..: :
': :~
:.::
6i.:
-'
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!
•;
k
- - 1
-
t
.: :::'_. ;r .__" !
-;
r*
. - - - - 1
:.' ''.- "'-
I
..:::-::.--........
.,
. .;-_
; . ;
: v.~.~~.\
__j—,
: : :.. :\
cEa
o•o
11
GJ
cc
j-<oOJszCO
CJr—
>
crllj
Shear Stress
|:;i:!::f:: j :
. ;•:-;:;; : ; u
/{'_' I . \
1 .....
/ 1
/
/;-:
1
i
;":1 ... .
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:
7. :
:-::::: - !-.-: •— : :.:..::;-
;
;
t .-::i: ;; \-\-\,::\i:\:^
.
r; ;:::: :
—: :
1
- : \,'y---' r: -^
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6 : ::•::';-.:;.-
: •
':
i: : :
:: :i_: ::::
;
;
: :[: :'::::
-;
.':
{, -i: -: ;
;: ii ;
:;
i
; :
; i:|
Direct Shear Vane Shear
Water Content {%): 159-7
1 mm = 1.5 lb. 1 mm - .11 psi
10
20
CDOJ*o
co•t—
-t-->
oa:
OJca>•
30
• 40
Figure A- 23 Test Results - Sample ATL
Page 234
10 5
Date: 11/19/76 Tested by: J. Foster
Sample if: t,-vj Water depth: i.cyj^ ™ Sample depth: ± 11 m
25 ram/mi n Chart speed 25 mm/mi
n
20 v Signal Conditioner 6 v
10 mv Sensitivity 20 mv
9.0 psi Normal Stress, Consolidation Pressure 9.0 psi
ll..26 psi T 2.53 P si
4->
o>EQJO
to
CJ
to
0.1
0.2
Shear Stress
I
!: - \l : :!::. :-
i
- "
-
! \
:-_;--::.!::::::
1
!
K: ::^; :-:!:-:
t--- •
. . 1 . .
.: •.(...::
: . .. .. :: ._
.: ::_-. .. :. ::.{:.:.:
./:
-.
: :.: ! :
1
:::::: -
::::-::=—
J . :
;:•-:: ;»~::-:»-jb.-. .. ._ -i
t
-.:•:•.- I
'
:'
:~
!
; : --::::.-.::! :
J ^
.-.-, ;;;f
ct—E
o
ii
CJ+->
acc
s-
ac/>
cCJr—
>•r—rscr
Shear Stress
f=-a=:i :i:~:
! |:-1:
i:^:\--':v \r\'
S::.:\. :::.:::: L/. i.E
f,
Jj
: :
/ ;
...:::: / j
^:\\ ::: j:
~\:\ J/ V~:
: ::.j.-:- ::::-
:"
••:: ' :: r.:\ ::-.— ;-.
:_::: . :j\ ~:~
.-
: :-'
...:..- ...:•|
::::: .; ;.-:." :
: : ||
1
:
t: - '
:
:\:\^':
,
:
':- '.:::'.: t.L-":rrf:: -•! .:: ;
;
-*
i
~~ -^
•:
•
- .
; ,
";
|
10
20
30
Direct Shear Vane Shear
Water Content {%): 156.5
1 mm = 1.5 lb. 1 mm = .11 psi
40
CnCJX>
ao•i—+->
to
o
CJ
f3
Figure A- 2ij. Test Results - Sample ATL
Page 236
106
Date: H/22/76 Tested by: J. Foster
Sample il: ATI Water depth: h.935 m Sample depth: ± 11 m.
25 mm/mi
n
Chart speed 25 mn/min
20 v Signal Conditioner G v
10 mv Sensitivity 20 mv
12.0psi Normal Stress, Consolidation Pressure 12. Ops i
5.52 psi_5lMZ_
2.86 psi
4->
o
to
0.1
0.2
Shear Stress
I;:! •;.!:::!
:
1.
: ;;;
::[-: - .:-\ \ :
:l \
— -—
! 1
:::,:..: I
-.-I : i-IL::
.:-::: ; :=l':\_ :
-1 :.: .
'--' '}'• -'
;,':. / :V::^i^~ ! ~:l
-::_" /:- i-L-:::-
- :;:-;;,;:::_;.--.-....:..
• .~.t-.---!:
•:
•
:.:: :::
p:::.?.
*~;"'
;
cEc
o
II
<u+->
res
c£
j-roO-CtO
4->
Ca
Shear Stress
Direct Shear Vane Shear
Water Content (%): 153-6
1 mm B 1.5.1b. 1 mm = .11 psi
10
20
30
40
en
o
to+->
occ
OJ
>•
Figure A- 25 Test Results - Sample ATL
Page 238
107
PLATE 1 DIRECT SHEAR TEST APPARATUS
Page 240
108
mi
,
PLATE 2 DIRECT SHEAR LOAD CELL
Page 242
109
'•:'.
: > -'- ?
'
\i'<
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#
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-":-
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;
H5: --S3p"<&2v^ r -'.iVi!
3
i
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\:f. I- r*
£<**'v •'?'>*• L^i^c !
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.n
- ....;
fe*
3 .-.'Vt-:'.:.
PLATE 3. Strain gage conditioner and data strip recorder
Page 244
110
-
'|
• .'--V 1'" V V '
A r? Q r'
''V- \ •'--•
« -.
• -V '--
ST?9t3iaA^3Bt-.«b «£% ..'•yasBS^Sid .;••".'. %.%
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PLATE 4 DIRECT SHEAR BOX, RING ADAPTERS,AND PRESSURE PLATES
Page 246
Ill
tf?f- • 4-J-
'
-fh
«
i
i
:
i •
J .- V
I
&E&gsiBsaS!ES3S3SaES2»iS5E :-»>.»
PLATE 5 ASSEMBLED MODIFIED DIRECT SHEAR BOXAND PRESSURE PLATE
Page 248
112
SI™""-— - ~r
^•«m>^. in ----- f-• w4
^ -' ' f '
s*n **M' t :;
PLATE 6 CHECKING HORIZONTAL DISPLACEMENTDURING DIRECT SHEAR TEST
Page 250
113
',
«;
:;
is
i
rwl*
rf
PLATE 7 MONITORING CONSOLIDATION IN DIRECTSHEAR MACHINE
Page 252
llil
*^-v?'.-w.Ty.v*«^!W»V 'u*' '
'
L ' •""''"*»- - '
-
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,
<:1 '•:'
'
542988
PLATE 8 VANE SHEAR MACHINE, STRAIN GAGE VANETORQUE PICK-UP REPLACEMENT
Page 254
115
— - — - — - •-- - - - -- •
-
~7V'
'*• "»-" B " r_^~
ni ir
PLATE 9 MODIFIED WYKHAM-FARRANCE VANE SHEAR MACHINE
Page 256
116
PLATE 10 VANE SHEAR TEST IN PROGRESS WITH SAMPLEIN DIRECT SHEAR BOX
Page 262
I
Thesis
IF654Foster
i
7
4 ?65
Determination ot
undrained shear
^
strength of marine
clays by combined
vane and direct shear
analysis.
ThesisF654 Foster
Determination ofundrained shearstrength of marineclays by combinedvane and direct shearanalysis.
171265
University „. WashingtonDeportment of Printing
Seottle. Washington 98195