Revised Geo Technical Reports of Trishuli River Bridge at Nuwakot

7/23/2019 Revised Geo Technical Reports of Trishuli River Bridge at Nuwakot

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Prepared By: Date: Octo ber, 2015

RIDARC Drilling and Geo-Technical Pvt. Ltd.Sainbu VDC - 2, Bhaisepati, Lalitpur

Phone / Fax No: 01-5593065, Contract No: 9851016051, 9741137840E-mail:[email protected]&[email protected]

Detailed Soil Investigation ofTrishuli River Bridge,Ratmate-08, Khalte

to

Budhasingh-01, ChipletteNuwakot

Client:Department of Roads, Bridge Branch

Babarmahal, Kathmandu

REPORT

ON

Prepared For:

ANK- Lumbini- Himdung J/V
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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Acknowledgement

Sainbu VDC - 2, Bhaisepati, Lalitpur, Contract No: 9851016051, 9741137840, E-mail:[email protected] Pagei

ACKNOWLEDGEMENT

We are grateful to M/s Bridge Branch, DoR and

ANK- Lumbini- Himdung J/V for providing us theopportunity to carry out these investigations.

The co-operation extended by their clientsEngineers, Sub- Engineers and other Field Staffduring field investigations is thankfully

acknowledged.
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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Table of Contents

Sainbu VDC - 2, Bhaisepati, Lalitpur, Contract No: 9851016051, 9741137840, E-mail:[email protected] Pageii

Table of Content1. GENERAL INTRODUCTION ....................................................................................................... 1

1.1 Background .............................................................................................................................. 1

1.2 General Geology, Geomorphology and Seismicity.................................................................. 1

2. OBJECTIVES ................................................................................................................................. 2

3. Scope of Investigation..................................................................................................................... 2

4. Methodology ................................................................................................................................... 2

4.1 Field Tests ................................................................................................................................ 2

4.2 Sampling................................................................................................................................... 3

4.3 Ground Water Table ................................................................................................................. 4

4.4 Laboratory Tests ....................................................................................................................... 4

4.5 Strata Analysis.......................................................................................................................... 4

4.6 Bearing Capacity Analysis ....................................................................................................... 4

4.6.1 Depth of Foundation ......................................................................................................... 4

4.6.2 Bearing Capacity of Soil ................................................................................................... 5

4.6.3 Stress distribution in Soils ............................................................................................. 5

4.7 Bearing Capacity Calculation................................................................................................... 5

4.7.1 Bearing capacity From In-situ Test.............................................................................. 5

4.8 Liquefaction ........................................................................................................................... 10

5. OBSERVATIONS AND RESULTS ............................................................................................ 11

5.1 Field Investigation Results ..................................................................................................... 11

5.2 Laboratory Investigation Results ........................................................................................... 11

5.2.1 Index Properties ........................................................................................................... 11

5.2.2 Strength Parameters .................................................................................................... 12

5.3 Settlement ............................................................................................................................... 12

6. Analysis of Data ............................................................................................................................ 12

6.1 Bearing Capacity .................................................................................................................... 12

6.2 D50Calculations ..................................................................................................................... 19

7 DESIGN PARAMETERS ............................................................................................................ 19

8 RECOMMENDATION ................................................................................................................ 20

Annexes:Bore Hole LogsTest Result Summary Sheet

Laboratory Test ResultFiguresPhotographs


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Abbreviation

Sainbu VDC - 2, Bhaisepati, Lalitpur, Contract No: 9851016051, 9741137840, E-mail:[email protected] Pageii i

LIST OF ABBREVIATION

SPT Standard Penetration Tests

DCPT Dynamic Cone PenetrationTestADB Asian Development BankADT Average Daily TrafficARE Assistant Resident EngineerASTM American Standards for Testing MaterialsAWBR All Weather Bituminous RoadAWGT All Weather Gravel TrackBM Benchmark/sBOQ Bill of QuantitiesCAD Computer Aided DraftingCBR California Bearing Ratio

CPM Critical Path MethodCV Curriculum VitaeDCP Dynamic Cone PenetrationDLP Defects Liability PeriodDOR Department of RoadsDTM Digital terrain ModelingEIA Environmental Impact AssessmentEMAP Environmental Management Action PlanEMG Environmental Management GuidelinesEPA Environmental Protection ActEPR Environmental Protection Rules

ESA Equivalent Single Axle/sEV Earned ValueFWET Fair weather Earth TrackFWGT Fair weather Gravel TrackGEU Geo-environmental UnitGON Government of NepalHRD Human resource DevelopmentICB International Competitive BiddingIEE Initial Environmental ExaminationIOW Inspector of WorksIRC Indian Roads CongressJV Joint VentureKm Kilometer/sMIS Management Information SystemNCB National Competitive BiddingNRRL Norwegian Road Research LaboratoryPAF Project Affected FamiliesPIP Priority Investment ProgramPOL Petroleum, Oil and LubricantPQ Pre-qualificationPWD Public work Directive

QAP Quality Assurance PlanRAP Resettlement Action PlanRMDP Road Maintenance and Development Project


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Trishuli River Bridge, Nuwakot

Sainbu VDC - 2, Bhaisepati, Lalitpur, Contract No: 9851016051, 9741137840, E-mail:[email protected] Page1

Soil Investigation Works of Trishuli River Bridge, Nuwakot

1. GENERAL INTRODUCTION

This report is prepared in accordance with the agreement between Bridge Branch, DoR and

ANK- Lumbini- Himdung J/V and RIDARC Drilling & Geo-Technical Pvt. Ltd., Sainbu,

Lalitpur to determine the bearing capacity and subsurface exploration of bridge site at

Trishuli River at Ratmate-08, Khalte to Budhasingh-01, Chiplette, Nuwakot District.

Site has been proposed to make two bore holes for sub surface exploration, which is located

at Ratmate-08, Khalte to Budhasingh-01, Chiplette, Nuwakot District. The site is nearer to

the vehicular approach of Galchhi to Bidur link road.

1.1 Background

The main objective of this Soil Investigation is to explain geotechnical characteristics of the

sub-soil strata, (i) to express the engineering properties of the sub-soil (ii) to confirm the

value of bearing capacity of the soil.

1.2 General Geology, Geomorphology and Seismicity

The site is located at the latitude of 2751'25 N and longitude of 850328 E; of Nuwakot

in the lesser Himalaya region of Nepal which is a part of the metasediments. The geological

formation of the lesser Himalaya is different types of sedimentary and metamorphic rocks

such as sandstones, silt, conglomerates, lime stone, quartzites, schists, etc. The

formations are occasionally mixed with local sandstones, silt, conglomerates, lime stone,

quartzites and schists.

Geologically, the lesser Himalaya are covered by glaciers where boulders, sand and stone

brought by glacier are found. Glaciers in the lesser Himalaya are deposited by the rivers

originating and coming from the Himalaya and they make fan shape deposition at the exit

point of the river. It is also observed that the same pattern continued in earlier times for the

deposition of older sediment. From the depositional pattern it is found that boulder and

cobbles are deposited in the form of fan in the mouth of river, whereas fines are deposited

further away.

In lesser Himalaya the parent rocks being the lower and upper formation of metasedimentsconsisting of sandstones, silt, conglomerates, lime stone, quartzites, schists, etc. The land


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form of lesser Himalaya has been divided as metasediments and crystalline, the

metasediments where both erosion and deposition are not occurring.

Generally, the sandstones, silt, conglomerates, lime stone, quartzites and schists arecompact. Its bearing capacity is high. Locally this unit is not prone to erosion and flooding.

There is no liquefaction.

As a matter of fact, the project site is in a Himalaya area having sandstones, silt,

conglomerates, lime stone, quartzites, schists in their textures without any soft cohesive

traces in the vicinity of the site. The deposits are in loose to medium denseness in state.

So both banks are slightly eroded during rainy season. The river depth is low and flows in

the wider width at the bridge axis.

2. OBJECTIVES

The main objective of this investigation is to explore geotechnical characteristics of the

subsoil strata, (i) to assess the engineering properties of the sub-soil; (ii) to confirm the

assumed value of bearing capacity of the ground strata during design of foundation, and

(iii) to confirm the design parameters to be used during the detailed design of the foundation

of the proposed site.

3. SCOPE OF INVESTIGATION

The scope of work includes drilling of two boreholes, each of greater than 19.0 m deep,

along with dynamic cone penetration test, standard penetration test, retrieving samples

from the boreholes and evaluation of allowable bearing capacity of the foundation based

on field and laboratory test.

4. METHODOLOGY

The following are the methodology adopted to meet the objectives.

4.1 Field Tests

The SPT is done to find the strength of soil in field at every interval of 1.5 m in each BH.

Standard Penetration Tests: It consists of driving a Split Spoon sampler with an outside

dia. of 50 mm into the soil at the base of borehole. Driving is accomplished by a drop of

hammer weighing 63.5 kg falling freely through a height of 750 mm onto the drive head.


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First of all the spoon is driven 150 mm into the soil at the bottom of the borehole. It is then

driven further 300 mm and the number of blows (N values) required to drive this distance

is recorded.

Dynamic Cone Penetration Test (DCPT): It consists of driving a cone by blows of

hammers. The number of blows for driving the cone through a specified distance is a

measure of the dynamic cone resistance.

Dynamic Cone Penetration test are performed by a 50 mm cone. The driving energy is

given by a 63.5 kg falling freely through a height of 750 mm onto the drive head. First of

all the cone is driven 100 mm into the soil at the bottom of the bore hole. It is then driven

further 200 mm and the number of blows (Ncbrvalues) required to drive this distance isrecorded.

The result i.e., Ncvalues first corrected to the Standard Penetration Test (SPT) value (N)

and that provides and estimation of degree of compaction of soil strata, values of angles of

internal friction () and allowable bearing capacity. The dynamic cone resistance is

correlated with the SPT (N) as given below.

Nc = 1.5 N for depth up to 3 m

= 1.75 N for depth 3 to 6 m

= 2 N for depth greater than 6 m

4.2 Sampling

(i) Disturbed Sample:

Before any sample was taken, the borehole was cleaned up of loose disturbed soil

deposited during boring operation. The samples which were obtained from bailer and in the

SPT tube were preserved as representative disturbed samples for finding out index

properties. The samples thus obtained were placed in airtight double plastic bags, labeled

properly for identification and later transported to the lab for analysis.

(ii) Undisturbed Sample:

Undisturbed Sample was extracted by means of thin wall tube (Shelby tube). The tube was

pushed into the ground and the sample recovered mechanically. The tube was sealed with


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wax and wrapped with airtight polythene sheets and then bound by adhesive tapes and

properly labeled. The tube was properly packed in a wooden box so as to minimize the

disturbances during transportation to the laboratory and avoided the changes of moisture

content of sample. This sample was used for the determination of strength andconsolidation parameters.

But undisturbed samples could not be obtained in this site.

4.3 Ground Water Table

Ground Water Table (GWT) was not observed during the drilling, which is mentioned in the

borehole logs.

4.4 Laboratory Tests

Disturbed and Undisturbed samples collected in core boxes, were transported to lab in

Bhainsepati, Lalitpur for the following tests.

Index property Test

a) Sieve Analysis

b) Natural Moisture Contentc) Bulk Density & Dry Density

d) Specific Gravity

f) Atterbergs Limit

Strength Parameter Test

a) Direct Shear Test

4.5 Strata Analysis

The project area lies in the Nuwakot district. The area is found of sand and boulder with

some layers of clay.

4.6 Bearing Capacity Analysis

4.6.1 Depth of Foundation

Strata of site consists of sand and boulder along with a clayey gravel layer. A pile

foundation or pile foundation for varying depth is considered for SBC calculation, so that

the designer can choose the depth according to capacity required and scour depth

provision.


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4.6.2 Bearing Capacity of Soil

The stratum being non-homogeneous consisting with sand and boulder and sandy clay the

computation of bearing capacity of the strata for foundation is derived from the SPT testand laboratory method.

4.6.3 Stress distribution in Soils

The Boussinesq's equation can be used to get stress distribution analysis for stress at

depths below the foundation level.

L = 6 m, B = 6 m

L/B = 6/6 = 1.0

For square footing the effective pressure below B; (depth equal to width of footing, 6.0 m,

or 12.0 m below GL) below the foundation bed, the remaining pressure is reduce about

1/3rdof total value.

The investigation work is to 16 m. The stress distribution at a depth of 7.0 m below ground

level is only 1/3rdof stress developed at the foundation level and seems very low. So there

will not be any major geotechnical changes in the strata below the depth of investigation.

4.7 Bearing Capacity Calculation

4.7.1 Bearing capacity From In-situ Test

Correction of N value from SPT

i) Overburden Correction

for overburden, as suggested by Peck et.al. (1974).

N corr = 0.77 Nreclog (2000/v')

Where, v' = Effective Overburden pressure (KN/m2)

N rec = SPT value Recorded

ii) Dilatancy Correction

Terzaghi and Peak (1976) give correction for water pressure.

If, Nrec 15, then Ncorr= Nrec


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If Nrec 15, then Ncorr= 15+1/2(Nrcc15)

Then for bearing capacity analysis Ncorris used as the N in the Correlation provided

by different researcher.

iii) Standardize Field Penetration Value:

N60 = 60

RSBHrecN

Where,

N60 = Standard penetration number, corrected for field conditions to an

Average energy ration of 60%

Nrec = measured penetration number

H = hammer efficiency (%)

B = correction for borehole diameter

S = sampler correction

R = correction for rod length

iv) Using Meyerhof's (1965) & Bowles (1977) Correlation

qsafe = 11.98N 1

2

2528.3

128.3wd Rx

Sf

B

B

Where,

N = Standard Penetration Value

B = width (m)

S = Settlement (mm)

fd = 1+0.33 (D/B) 1.33

Rw1 = water correction factor = 0.5

Allowable Bearing Pressure

The allowable bearing pressure (qa) is the maximum pressure that can be imposed on the

foundation soil taking into consideration the ultimate bearing capacity of the soil and the

tolerable settlement of the structure. Analysis to determine the ultimate bearing capacity

and the pressure corresponding to a specified maximum settlement were performed and

the minimum pressure obtained from the two analyses were adopted as the allowable

bearing pressure.

ALLOWABLE BEARING PRESSURE BASED ON ULTIMATE BEARING CAPACITY

Since the soil in the vicinity of the foundation level has been found to be granular or non-

plastic, cohesion less sand through-out the site, the allowable bearing capacity has been


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analyzed using the N-values from SPT results. Empirical formula of Teng (1988) applicable

for this type of soils has been used to obtain the allowable bearing pressure with safety

factor equal to 3.

For Open foundation:

qa= 3 NBRw + 5(100+N)DRw (4.1)

qa= 2 NBRw+ 6(100+N)DRw (4.2)

For Bored Piles:

Qu= 133 N Ab+ 0.67 N As (4.3)

Where: qa =Q/4= net allowable bearing pressure, KN

N = SPT value corrected with respected to overburden

B = width of footing, ft

D = depth of footing, ft

Rw& Rw= correction factors for position of water level

Qu = Ultimate total load in KN

N= Average SPT value below pile tip

N = Average SPT value along pile Shaft

AS= Shaft Surface area of pile in m2

Ab= Base area of pile in m2

Qa= Qu/ 4

Qa= Safe load for pile

ALLOWABLE BEARING PRESSURE BASED ON TOLERABLE SETTLEMENT

The maximum allowable settlement for footings in sand is generally 40 mm and format

foundation in sand the allowable settlement is 65 mm (Skempton and MacDonald, 1955).


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The method of Teng (1988) has been employed for the analysis. This method is a

modification of the method of Terzaghi and Peck (1948) such that the allowable bearing

pressure could directly be obtained from the SPT values.

For open and well foundations:

AS per IS: 3935(1967), for well foundation

Allowable pressure (qa) = 0.054N2B+ 0.16(100+N2) D for cohesion less soil

For cohesive soil the laboratory method is used.

For Mat

qna= 1.75(N-3)Rw for 25 mm settlement

According to Is: 6403

qna= 1.27(N-3)for 65 mm settlement

For Bored Pile

qna = (133*N * Ab+ 0.67 * As* N)/3

Where,

N = SPT value at Base of Pile

N= Average SPT value across length of pile

Ab= Area of base of pile

As= Surface area of pile

Qna= allowable load for pile in KN

Where, qa is the net allowable bearing pressure in psf for maximum settlement of 25 mm.

The other notations are the same as in Eqs. 4.1.

The minimum average SPT values from the boreholes in each structure have been selected

for the analysis of bearing capacity of the relevant structure.

The allowable bearing pressure for a limiting settlement other than 25 mm (e.g. x mm) can

be linearly interpolated from the allowable bearing pressure for 25 mm settlement.

qa(x mm) = qa(25 mm)(x/25)

B

DRw

B

BNq 1'

2

1)3(720

2


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4.7.2 Bearing Capacity from Laboratory Tests

In sandy soil the failure is generally shear failure and the bearing capacity is governed bythe shear properties i.e. C and . Direct shear test from disturbed samples shows that the

average value of angle of friction is greater than 280. Then the failure condition of these

strata should be considered as general shear failure. This is the general rule that local

shear cannot occur in dense gravelly strata.

Considering the worst condition of water table at ground, either suitable correction factor

of Rw' (0.5) or submerged unit weight of the strata should be used for getting the ultimate

bearing capacity, assuming that the whole depth is saturated.

From Terzaghi's equation

For open Foundation

qult = 1.2 CNc + DfNq Rw1+ 0.4 BNRw2

qsafe = qult / F.S.

For pile foundation

Q = (CuNc + Df (Nq-1))*Ab+ (Cu+ K tan) As

Qa = qult / F.S.

Where,

AS= Shaft Surface area of pile in m2

Ab= Base area of pile in m2

= Adhesion factor

K = earth pressure factor

= angle of internal friction

Cu= Undrained cohesion = undrained shear strength

= unit weight of the soil (T/m3)

Nc, Nq& Nare bearing capacity factors

B = Width of foundation (m)

D = Depth of foundation (m)

F.S. = Factor of safety i.e., 3


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Rw1& Rw2 = Water correction factor = 0.5 for ground level

If local shear failure occurs,

Then, ' = tan-1[2/3 tan ]

C' = 2/3C

Bearing Capacity by Meyerhof's Correlation for Pile Foundation

Safe Load (Qall) =..SF

QQ sp

Where,

Qp = Ultimate point bearing capacity (KN)

Qs = Ultimate skin resistance (KN)Qp = ApqNq

Qs = CuP L (for cohesive soil layers)

Qs = pf L (for cohesion less soil layers)

Where,

p = Pile perimeter = Dp

f = Unit frictional (or skin) resistance

= Kotan

= 300(assumed for sandy layers)

Ap = Area of Pile

Cu = Undrained Cohesion = 30 KN/m2

= Co-efficient of adhesion (factor)

= 0.8

Nq = 50.0

L = Length of pile in clayey (70.0 m) or sandy strata (6.0 m)sat = 18 KN/m

3

Dp = Diameter of pile i.e. 0.5m

F.S. = Factor of safety i.e. usually 3 is taken

Results:The stratigraphy profiles of all boreholes at the proposed depth of pile foundation

level have in same order and (N) value also more or less same. So, a single average value is

taken for all boreholes.

4.8 Liquefaction


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When fine or medium, saturated, loose sand deposit is subjected to a sudden shock

(generated by an earthquake) the mass will temporarily liquefy. This phenomenon is

termed 'Liquefaction'. When liquefaction takes place in a particular soil then the bearing

capacity of the soil disappears and the structure built on it gets tilts or even sinks.The past big earthquakes, have shown that saturated sandy soils in a loose to medium

dense condition were liquefied during earthquakes varying in magnitude from 5.5 to 8.5

(Richter scale) and epicenter distance from several miles to hundreds of miles.

From the case studies, liquefaction potential characteristics of the soil depend on:

1) The soil contains less than 10 percent fines (silt and clay sizes)

2) D60 is between 0.2 mm and 1.0 mm

3) Cu (D60/D10) is between 2 and 5; and

4) The blow count per 30 cm standard penetration tests is less than 15.0

Where:

D60 = 60 percent of the soil grains smaller than that size.

D10 = 10 percent of the soil grains smaller than corresponding size

Cu = Coefficient of uniformity = D60/D10

5. OBSERVATIONS AND RESULTS

5.1 Field Investigation Results

Logging of the bore holes were carried out at the site during boring period. The logs were

reconfirmed and suitably corrected based on the laboratory test results. The logs of the

boreholes are provided in annexes show that clay with silt.

Measured SPT values are 39 to 75 in the in-situ soil strata at different levels. Measured

value shows that the layers are medium dense to very densely compacted.The seepage ground water table was not observed.

5.2 Laboratory Investigation Results

5.2.1 Index Properties

The results of physical and index properties of soil samples collected from various depths

are presented in the attached summary sheet.

The grain size distribution curves of soil sample are classified as USCS Soil Classification

System. As per USCS Soil Classification System most of the soils are in GP group.


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5.2.2 Strength Parameters

Direct Shear Test was conducted on undisturbed and representative disturbed samples.

The cohesion (c) and angle of internal friction () of the soil up to 19 m in BH1 and 25 m in

BH2 is found in the range of 0 to 7 KN/m 2 and 230 to 320 respectively. The strength

parameter leads to give medium to high shear strength value.

5.3 Settlement

For heavier and important structure consolidation settlement should be predicted by the

following equation.

SOc = Hi* (Cc/(1+eo) log {(p0 + p)/ p0}

Where, SOc= long term settlement, cm

Hi = thickness of each layer

Po = effective overburden pressure before load application

p = the excess pressure due to superposition of load

Cc = Compression index

eo= initial void Ratio

Then, Total settlement (Sc) = * SOc

Where, = average pore pressure coefficient

6. ANALYSIS OF DATA

6.1 Bearing Capacity

a The sample on the right bank (BH-2) consists of soft rock from 3 m depth. The rock samples

obtained were in pulverized or powder form. No RQD values could be obtained. So the soft

rock is treated as soil and the bearing capacity values are obtained as per below. However,

in the next section, the bearing capacity are calculated as per soft rock.

For open foundation, the Bearing Capacity values from field test results are summarized in

tabulated form:

Size of open foundation= 4.5 m X 4.5 m

BoreHoleNo.

Depth(m)

FieldrecordedSPT (N)Values

StandardizeN value N60

Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code(2950-1956)

(25 mmsettlement)

(T/m2)

Lower BCValues for

25 mmsettlement

(T/m2)

BC valuesfor 40 mmsettlement

(T/m2)

BH-1

3 75 51.56 42.28 42.49 42.28 67.65

4.5 63 43.31 38.72 35.27 35.27 61.95

6 64 44.00 42.59 35.88 35.88 68.147.5 54 37.13 38.68 29.86 29.86 61.89

9 58 39.88 44.49 32.27 32.27 71.19


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BH-2

3 46 31.63 25.93 25.05 25.05 41.49

4.5 75 51.56 46.10 42.49 42.49 73.75

6 75 51.56 49.91 42.49 42.49 79.85

7.5 75 51.56 53.72 42.49 42.49 85.95

9 75 51.56 57.53 42.49 42.49 92.05


BoreHoleNo.

Depth(m)



Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code(2950-1956)

(25 mmsettlement)

(T/m2)

Lower BCValues for

25 mmsettlement

(T/m2)


(T/m2)

BH-1

3 75 51.56 41.00 42.49 41.00 65.59

4.5 63 43.31 37.28 35.27 35.27 59.65

6 64 44.00 40.76 35.88 35.88 65.22

7.5 54 37.13 36.83 29.86 29.86 58.939 58 39.88 42.18 32.27 32.27 67.49

BH-2

3 46 31.63 25.14 25.05 25.05 40.23

4.5 75 51.56 44.38 42.49 42.49 71.01

6 75 51.56 47.77 42.49 42.49 76.43

7.5 75 51.56 51.16 42.49 42.49 81.85

9 75 51.56 54.55 42.49 42.49 87.27


BoreHoleNo.

Depth(m)

Field

recordedSPT (N)Values


Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code

(2950-1956)(25 mmsettlement)

(T/m2)

Lower BC

Values for25 mmsettlement

(T/m2)

BC values

for 40 mmsettlement

(T/m2)

BH-1

3 75 51.56 39.11 42.49 39.11 62.57

4.5 63 43.31 35.18 35.27 35.18 56.28

6 64 44.00 38.10 35.88 35.88 60.95

7.5 54 37.13 34.14 29.86 29.86 54.62

9 58 39.88 38.81 32.27 32.27 62.09

BH-2

3 46 31.63 23.99 25.05 23.99 38.38

4.5 75 51.56 41.88 42.49 41.88 67.00

6 75 51.56 44.64 42.49 42.49 71.43

7.5 75 51.56 47.41 42.49 42.49 75.86

9 75 51.56 50.18 42.49 42.49 80.29


BoreHoleNo.

Depth(m)



Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code(2950-1956)

(25 mmsettlement)

(T/m2)

Lower BCValues for

25 mmsettlement

(T/m2)


(T/m2)

BH-1

3 75 51.56 37.79 42.49 37.79 60.46

4.5 63 43.31 33.71 35.27 33.71 53.93

6 64 44.00 36.24 35.88 35.88 57.987.5 54 37.13 32.26 29.86 29.86 51.62

9 58 39.88 36.46 32.27 32.27 58.34


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BH-2

3 46 31.63 23.18 25.05 23.18 37.08

4.5 75 51.56 40.13 42.49 40.13 64.21

6 75 51.56 42.47 42.49 42.47 67.95

7.5 75 51.56 44.81 42.49 42.49 71.70

9 75 51.56 47.15 42.49 42.49 75.44


BoreHoleNo.

Depth(m)



Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code(2950-1956)

(25 mmsettlement)

(T/m2)

Lower BCValues for

25 mmsettlement

(T/m2)


(T/m2)

BH-1

3 75 51.56 36.81 42.49 36.81 58.90

4.5 63 43.31 32.63 35.27 32.63 52.20

6 64 44.00 34.87 35.88 34.87 55.80

7.5 54 37.13 30.89 29.86 29.86 49.429 58 39.88 34.74 32.27 32.27 55.58

BH-2

3 46 31.63 22.58 25.05 22.58 36.13

4.5 75 51.56 38.84 42.49 38.84 62.15

6 75 51.56 40.87 42.49 40.87 65.39

7.5 75 51.56 42.90 42.49 42.49 68.63

9 75 51.56 44.92 42.49 42.49 71.88


BoreHoleNo.

Depth(m)

Field

recordedSPT (N)Values


Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code

(2950-1956)(25 mmsettlement)

(T/m2)

Lower BC

Values for25 mmsettlement

(T/m2)

BC values

for 40 mmsettlement

(T/m2)

BH-1

3 75 51.56 36.07 42.49 36.07 57.71

4.5 63 43.31 31.80 35.27 31.80 50.88

6 64 44.00 33.83 35.88 33.83 54.13

7.5 54 37.13 29.83 29.86 29.83 47.73

9 58 39.88 33.42 32.27 32.27 53.47

BH-2

3 46 31.63 22.12 25.05 22.12 35.40

4.5 75 51.56 37.86 42.49 37.86 60.57

6 75 51.56 39.64 42.49 39.64 63.43

7.5 75 51.56 41.43 42.49 41.43 66.29

9 75 51.56 43.22 42.49 42.49 69.15


BoreHoleNo.

Depth(m)



Meyerhofs(1965) &

Bowles (1977)(25mm

Settlement)(T/m2)

IS Code(2950-1956)

(25 mmsettlement)

(T/m2)

Lower BCValues for

25 mmsettlement

(T/m2)


(T/m2)

BH-1

3 75 51.56 35.48 42.49 35.48 56.76

4.5 63 43.31 31.14 35.27 31.14 49.83

6 64 44.00 33.00 35.88 33.00 52.807.5 54 37.13 29.00 29.86 29.00 46.39

9 58 39.88 32.38 32.27 32.27 51.81


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BH-2

3 46 31.63 21.76 25.05 21.76 34.82

4.5 75 51.56 37.08 42.49 37.08 59.32

6 75 51.56 38.67 42.49 38.67 61.88

7.5 75 51.56 40.27 42.49 40.27 64.43

9 75 51.56 41.87 42.49 41.87 66.99

b The right bank (BH-2) consists of soft rock from 3 m depth. On the process of obtaining

samples, no such sample pieces required for obtaining RQD (core pieces greater than 10

cm) were obtained. The samples obtained were in pulverized form.

As per Bowles (1996), the Bearing capacity of rock can be obtained using Terzaghi

equations as,

qu= 1.3cNc+ qNq+ 0.4BN for square footing

where, the bearing capacity factors are calculated as:

)2

+45(tan5=N 4c

)2

+45(tan=N 6q

1+N=N q

The bearing capacity equation is for intact rock and does not account for the effect of

discontinuities. In our case, the sample obtained is pulverized, i.e. the sample is quite

discontinuous and the bearing capacity equation is not applicable.

Peck et al. (1974) have related the RQD to the allowable bearing pressure as

RQD qa(Mpa) qa(T/m2)

100 29 2900

90 19 1900

75 12 1200

50 6.25 625

25 3 3000 0.96 96

In our case, RQD=0, so allowable bearing pressure=96 T/m2


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c For well foundation, the Bearing Capacity values from field test results are summarized in

tabulated form:

Well Foundation For Borehole 1 (Left Bank)

BHno.

Diameter(B) (m)

Depth (D)(m)

Nvalues

IS 3955 (1967)(T/m2)

Terzaghi and Peck(1948) (T/m2)

Least Value(T/m2)

1

5 6 51.56 336.62 276.92 276.92

5 7.5 43.31 287.77 261.23 261.23

5 9 44.00 345.46 297.56 297.56

5 10.5 37.13 285.56 274.20 274.20

5 12 39.88 367.41 324.97 324.97

5 13.5 35.06 320.34 307.49 307.49

5 15 25.44 196.77 232.63 196.77

5 16.5 28.88 269.03 288.39 269.03

5 18 35.06 416.05 382.29 382.29

1

6 6 51.56 350.98 237.96 237.96

6 7.5 43.31 297.90 222.22 222.22

6 9 44.00 355.91 251.13 251.13

6 10.5 37.13 293.00 229.92 229.92

6 12 39.88 376.00 271.03 271.03

6 13.5 35.06 326.98 255.30 255.30

6 15 25.44 200.26 192.40 192.40

6 16.5 28.88 273.53 237.73 237.73

6 18 35.06 422.69 314.21 314.21

1

7 6 51.56 365.33 212.03 212.03

7 7.5 43.31 308.03 196.32 196.327 9 44.00 366.36 220.32 220.32

7 10.5 37.13 300.45 200.57 200.57

7 12 39.88 384.59 235.31 235.31

7 13.5 35.06 333.62 220.75 220.75

7 15 25.44 203.76 165.79 165.79

7 16.5 28.88 278.03 204.22 204.22

7 18 35.06 429.33 269.21 269.21

1

8 6 51.56 379.69 193.61 193.61

8 7.5 43.31 318.16 177.93 177.93

8 9 44.00 376.82 198.48 198.48

8 10.5 37.13 307.89 179.78 179.788 12 39.88 393.17 210.01 210.01

8 13.5 35.06 340.26 196.30 196.30

8 15 25.44 207.25 146.96 146.96

8 16.5 28.88 282.53 180.52 180.52

8 18 35.06 435.97 237.39 237.39

1

9 6 51.56 394.05 179.86 179.86

9 7.5 43.31 328.29 164.24 164.24

9 9 44.00 387.27 182.22 182.22

9 10.5 37.13 315.33 164.31 164.31

9 12 39.88 401.76 191.20 191.20

9 13.5 35.06 346.89 178.13 178.13

9 15 25.44 210.74 132.96 132.96

9 16.5 28.88 287.04 162.92 162.92

9 18 35.06 442.61 213.75 213.75


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Well Foundation For Borehole 2 (Right Bank)

BHno.

Diameter(B) (m)

Depth (D)(m)

Nvalues

IS 3955 (1967)(T/m2)

Terzaghi and Peck(1948) (T/m2)

Least Value(T/m2)

2

5 6 31.63 132.62 163.23 132.62

5 7.5 51.56 402.83 314.69 314.69

5 9 51.56 469.04 352.45 352.45

5 10.5 51.56 535.24 390.21 390.21

5 12 51.56 601.45 427.97 427.97

5 13.5 51.56 667.66 465.73 465.73

5 15 51.56 733.87 503.50 503.50

5 16.5 51.56 800.08 541.26 541.26

5 18 51.56 866.29 579.02 579.02

2

6 6 31.63 138.02 140.26 138.02

6 7.5 51.56 417.18 267.70 267.70

6 9 51.56 483.39 297.45 297.45

6 10.5 51.56 549.60 327.19 327.19

6 12 51.56 615.81 356.93 356.93

6 13.5 51.56 682.02 386.68 386.68

6 15 51.56 748.23 416.42 416.42

6 16.5 51.56 814.44 446.17 446.17

6 18 51.56 880.64 475.91 475.91

2

7 6 31.63 143.42 124.98 124.98

7 7.5 51.56 431.54 236.50 236.50

7 9 51.56 497.75 260.96 260.96

7 10.5 51.56 563.96 285.43 285.43

7 12 51.56 630.17 309.89 309.89

7 13.5 51.56 696.38 334.36 334.367 15 51.56 762.58 358.82 358.82

7 16.5 51.56 828.79 383.29 383.29

7 18 51.56 895.00 407.76 407.76

2

8 6 31.63 148.82 114.12 114.12

8 7.5 51.56 445.90 214.35 214.35

8 9 51.56 512.11 235.09 235.09

8 10.5 51.56 578.32 255.84 255.84

8 12 51.56 644.52 276.58 276.58

8 13.5 51.56 710.73 297.32 297.32

8 15 51.56 776.94 318.07 318.07

8 16.5 51.56 843.15 338.81 338.818 18 51.56 909.36 359.55 359.55

2

9 6 31.63 154.22 106.02 106.02

9 7.5 51.56 460.26 197.85 197.85

9 9 51.56 526.46 215.83 215.83

9 10.5 51.56 592.67 233.82 233.82

9 12 51.56 658.88 251.81 251.81

9 13.5 51.56 725.09 269.79 269.79

9 15 51.56 791.30 287.78 287.78

9 16.5 51.56 857.51 305.76 305.76

9 18 51.56 923.72 323.75 323.75


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d Considering Circular pile and pile cap (Mat) at 3.2 m from Surface

For Borehole 1 and 2 the Bearing Capacity values are tabulated as below:For 0.5 m Dia Circular Pile

Depth Qs Qb Qu FOS Qa( KN) Qa( T)

10 184.3 399.2 583.5 2.5 233.4 23.3

12 260.4 461.3 721.7 2.5 288.7 28.9

15 399.0 570.3 969.3 2.5 387.7 38.8

18 566.9 624.2 1191.1 2.5 476.4 47.6

20 695.1 691.0 1386.0 2.5 554.4 55.4

For 0.6 m Dia Circular Pile


10 221.2 574.8 796.0 2.5 318.4 31.8

12 312.5 664.3 976.8 2.5 390.7 39.1

15 478.8 821.2 1300.0 2.5 520.0 52.0

18 680.2 898.8 1579.1 2.5 631.6 63.2

20 834.1 995.0 1829.0 2.5 731.6 73.2



10 258.0 782.4 1040.4 2.5 416.2 41.6

12 364.6 904.2 1268.8 2.5 507.5 50.8

15 558.6 1117.8 1676.4 2.5 670.6 67.1

18 793.6 1223.4 2017.0 2.5 806.8 80.7

20 973.1 1354.3 2327.3 2.5 930.9 93.1



10 294.9 1021.9 1316.8 2.5 526.7 52.7

12 416.7 1181.0 1597.7 2.5 639.1 63.9

15 638.4 1460.0 2098.4 2.5 839.3 83.9

18 907.0 1597.9 2504.9 2.5 1002.0 100.2

20 1112.1 1768.8 2880.9 2.5 1152.4 115.2



10 331.7 1293.3 1625.1 2.5 650.0 65.0

12 468.8 1494.7 1963.4 2.5 785.4 78.5

15 718.2 1847.8 2566.0 2.5 1026.4 102.6

18 1020.4 2022.4 3042.8 2.5 1217.1 121.7

20 1251.1 2238.7 3489.8 2.5 1395.9 139.6


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6.2 D50Calculations

Bore Hole Depth (m) thicknessweighted meansize (mm)

D50 as perborehole (mm)

D50for thesite (mm)

BH-1

0 4.94

13.73

15.1

0 - 0.5 0.5 17.50

0.5 - 1.0 0.5 16.07

1.0 - 1.5 0.5 3.39

1.5 - 3.0 1.5 2.24

3.0 - 4.5 1.5 25.00

4.5 - 6.0 1.5 25.00

6.0 - 7.5 1.5 0.79

BH-2

0 1.78

16.48

0 - 0.5 0.5 2.32

0.5 - 1.0 0.5 4.93

1.0 - 1.5 0.5 2.19

1.5 - 3.0 1.5 3.05

3.0 - 4.5 1.5 25.00

4.5 - 6.0 1.5 25.00

6.0 - 7.5 1.5 25.00

7 DESIGN PARAMETERS

Unit weight of soil = 1.7 t/m2

Angle of internal friction = 300

Ground Water table: At the surface level (Considering Worst Condition)


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8 RECOMMENDATION

The results are shown in safe bearing capacity, it is recommended that:

i The safe allowable bearing capacity (tons/m2) for 4.5, 5.0, 6.0, 7.0, 8.0, 9.0 and

10.0 m width Open foundation at 3.0, 4.5, 6.0, 7.5 and 9.0 m depths (measured

from existing ground level) of site locations are as given below:

Size DepthBH1 BH2

BC (25 mmsettlement)




4.5 x 4.5 3 42.28 67.65 25.05 41.49

4.5 x 4.5 4.5 35.27 61.95 42.49 73.75

4.5 x 4.5 6 35.88 68.14 42.49 79.85

4.5 x 4.5 7.5 29.86 61.89 42.49 85.95

4.5 x 4.5 9 32.27 71.19 42.49 92.05

5.0 x 5.0 3 41.00 65.59 25.05 40.23

5.0 x 5.0 4.5 35.27 59.65 42.49 71.01

5.0 x 5.0 6 35.88 65.22 42.49 76.43

5.0 x 5.0 7.5 29.86 58.93 42.49 81.85

5.0 x 5.0 9 32.27 67.49 42.49 87.27

6.0 x 6.0 3 39.11 62.57 23.99 38.38

6.0 x 6.0 4.5 35.18 56.28 41.88 67.00

6.0 x 6.0 6 35.88 60.95 42.49 71.43

6.0 x 6.0 7.5 29.86 54.62 42.49 75.86

6.0 x 6.0

9 32.27 62.09 42.49 80.29

7.0 x 7.0 4.5 33.71 53.93 40.13 64.21

7.0 x 7.0 6 35.88 57.98 42.47 67.95

7.0 x 7.0 7.5 29.86 51.62 42.49 71.70

7.0 x 7.0 9 32.27 58.34 42.49 75.44

8.0 x 8.0 4.5 32.63 52.20 38.84 62.15

8.0 x 8.0 6 34.87 55.80 40.87 65.39

8.0 x 8.0 7.5 29.86 49.42 42.49 68.63

8.0 x 8.0 9 32.27 55.58 42.49 71.88

9.0 x 9.0 4.5 31.80 50.88 37.86 60.57

9.0 x 9.0 6 33.83 54.13 39.64 63.43

9.0 x 9.0 7.5 29.83 47.73 41.43 66.29

9.0 x 9.0 9 32.27 53.47 42.49 69.15

10.0 x 10.0 4.5 31.14 49.83 37.08 59.32

10.0 x 10.0 6 33.00 52.80 38.67 61.88

10.0 x 10.0 7.5 29.00 46.39 40.27 64.43

10.0 x 10.0 9 32.27 51.81 41.87 66.99

This bearing capacity values are calculated considering the discontinuous pulverized soft rock as

soil mass. However, the allowable bearing capacity values can be considered as 96 ton/m2for the

soft rock of Borehole 2 from the depth of 3.0 m.


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ii No consideration would be made for the consolidation settlement criteria.

iii Use an average friction angle of 30for soil and rock layers below the foundation

depth in both bore holes.

iv The value of D50 of the river bed material is 15.1 mm

v As the relatively high DCPT values are due to the presence of cobbles and boulders

in borehole location. Which may sometimes does not exactly represent the actual

site conditions and the above recommended bearing capacity may be unsafe. Thus,

it is recommended to check the average percentage of boulders and gravels and

weathered rock fragments including their denseness during the period of excavation

of the foundation. Provision of thicker PCC helps to reduce the weaker soil pockets

zones.


26/35


Sainbu VDC - 2, Bhaisepati, Lalitpur, Contract No: 9851016051, 9741137840, E-mail:[email protected]

Bore Hole Log


27/35



Test Result Summary Sheet


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Laboratory Test Result


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Figures


30/35




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Photographs


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DCPT at Bore Hole1 (Right Bank)

DCPT at Bore Hole2 (Left Bank)


33/35



Sample collection at BH-1 (Right Bank)

4.5 m

6.0 m

Loose sample for

sieve anal sis


34/35



Sample collection at BH-2 (Left Bank)

3.0 m

7.5 m

20.0 m

12.0 m

17.5 m


35/35


Revised Geo Technical Reports of Trishuli River Bridge at Nuwakot

Documents