GEOTECHNICAL INVESTIGATION TERMS Concrete & Materials Testing Laboratory Inc. #19 L. Intalan St., Bagong Ilog, Pasig City. Tel # 6559785 / 470-5412 FINAL REPORT ON " PROPOSED PAMPANGA RIVER SLOPE PROTECTION WORKS AT SAN ESTEBAN CUT - OFF CHANNEL PALIMPI ( PHASE 1 ) " Masantol Pampanga DPWH REGION 3 DPWH-BRS Accredited Laboratory
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GEOTECHNICAL INVESTIGATION
TERMS Concrete & Materials
Testing Laboratory Inc.#19 L. Intalan St., Bagong Ilog, Pasig City.
Tel # 6559785 / 470-5412
FINAL REPORT
ON
" PROPOSED PAMPANGA RIVER
SLOPE PROTECTION WORKS AT SAN
ESTEBAN CUT - OFF CHANNEL
PALIMPI ( PHASE 1 ) "
Masantol Pampanga
DPWH REGION 3
DPWH-BRS Accredited Laboratory
Cordon Isabela
Page
I. INTRODUCTION 1
II. FIELD INVESTIGATION 2
III. LABORATORY TESTING 2-4
IV. RESULTS OF FIELD AND LABORATORY TESTING 5
V. 5-7
A. Shallow Strip Foundation 5
B. Lateral Earth Pressure 5-6
C. Slope Stability 7
D. Mat Foundation with Underlying Soil Improvement 7
LIMITATIONS 8
Appendices
Final Boring Log
Laboratory Test Results
Drilling Photos
Bussiness Permit and License
Geotechnical Engineer's P. T. R.
FINAL REPORT
GEOTECHNICAL INVESTIGATION
" PROPOSED PAMPANGA RIVER SLOPE PROTECTION WORKS AT SAN ESTEBAN CUT - OFF CHANNEL
PALIMPI ( PHASE 1 ) "
Masantol Pampanga
TABLE OF CONTENTS
EVALUATION / RECOMMENDATIONS FOR LATERAL EARTH PRESSURE
ANALYSIS, SLOPE STABILITY and FOUNDATION DESIGN
Appendix D
Section
Appendix E
ATTACHMENTS
Appendix A
Appendix B
Appendix C
Page 1 of 8
EVALUATION OF GEOTECHNICAL CONDITIONS for the
PROPOSED PAMPANGA RIVER SLOPE PROTECTION WORKS AT SAN
ESTEBAN CUT - OFF CHANNEL PALIMPI ( PHASE 1 )
Masantol Pampanga
INTRODUCTION
This assessment of the geotechnical conditions in the above-mentioned project site is based on the findings gathered from the field and laboratory works conducted by Terms Concrete Testing. It is understood that the subsurface exploration program is to be intended for a revetment project. Included in this report are recommendations on design parameters for lateral earth pressure coefficients for slope stability analysis and design. One borehole at 34.50m depth were drilled for the soil exploration program. During drilling of soil-type material, Standard Penetration Test (SPT) and soil sampling were undertaken at regular interval of 1.5m. Upon encountering rock-type formation, the coring procedure would then be employed to penetrate through the hard strata and extract samples. The retrieved soil and/or rock samples were taken to the soil laboratory for various laboratory tests.
Page 2 of 8
II. FIELD INVESTIGATION
The field investigation consisted of drilling boreholes with Standard Penetration Test for the boreholes. The boreholes were advanced by wash boring to the specified boring depths. The SPTs, conducted at every 1.5 meter interval, consisted of driving a standard split spoon sampler of 5.08 cm (2 inches O.D.) diameter in three successive segments of 15 cm (6 inches) using a freely falling drop hammer of 63.6 kg (140 lbs) weight from a height of 76.2 cm (30 inches). The number of blows required to penetrate the three 15-cm layers are recorded. The blow counts of the last two layers are added to give the N-value of a particular 45cm stretch, a measure of density or consistency of the soil. SPT procedures are conducted in accordance to ASTM D-1586. Soil samples were retrieved using the spoon sampler. When very hard material including gravel and rock formation are encountered, coring procedure is employed. For rock-type samples, Rock-Quality Designation (RQD) was applied in describing their properties. RQD is a measure of the degree of jointing or fracture in a rock mass that is measured as a percentage of the drill core in lengths of 10 cm or more. High-quality rock has an RQD of more than 75% while low quality of has less than 50%. All the recovered soil samples and cored samples were brought to the soil laboratory for further testings.
III. LABORATORY TESTING Retrieved soil or cored samples from every 1.5m depth were subjected to the following laboratory tests in conformance with the procedures given in the current ASTM standards as described below: Grain Size Analysis as per ASTM D422 Sieve analyses were performed to determine the gradational characteristics of the soil in order to come up with soil classification information
Page 3 of 8
Determination of Moisture Content as per ASTM D2216 The method determines the water (moisture) content of soil by weight. Moisture content of soil is the ratio of the mass of pore water in a given soil mass to the mass of the solid material particles, given in percentage. Atterberg Limit Test as per ASTM D4318 (for plastic material) Atterberg Limits test of fine grained (i.e., clayey or silty) material were performed to come up with soil classification data and to determine moisture content at which the behavior of soil changes. Liquid Limit of Soils The liquid limit of soil is the water content (percentage in weight) of the oven-dried soil after reaching the condition between the liquid and plastic states. Plastic Limit of Soils The plastic limit of soil is the water content (percentage in weight) of the oven-dried soil after reaching the condition between the plastic and semi-solid states. Plasticity Index of Soils The plasticity index is defined as the difference between the liquid and plastic limits of the soil. Soil Classification Tests as per ASTM D2487 The soil samples were classified based on the Unified Soils Classification System (ASTM 2487) which is a universal format in identifying and classifying soil materials. Based on laboratory determination of particle size characteristics, liquid limit and plasticity index, the standard classifies mineral and organo-mineral soils for engineering purposes. Unconfined Compression Test ASTM D2938 Unconfined Compression Test (UCT) is a method in determining the mechanical properties of rocks and fine-grained soils. It gives a measure of the undrained strength and the stress-strain characteristics of the rock or soil. It is customary to include the unconfined compression test in the laboratory test program of geotechnical investigation specially when dealing with rocks. It should be noted that no UCTs were performed for rock samples which did not pass the requirement as test specimen, e.g. not intact sample to fulfill the specified dimensioning. Further, rock properties are identified through the following measures:
Page 4 of 8
Total core recovery (TCR)
TCR is the borehole core recovery percentage, defined as the quotient:
lsum of pieces = Sum of length of core pieces ltotal core run= Total length of core run
Rock Quality Designation (RQD) RQD is an approximate measure of the degree of jointing or fracture in a rock mass, measured as a percentage of the drill core in lengths of 100 mm or more. High-quality rock has an RQD of more than 75% while low quality of less than 50%. Whereas rock quality designation could have several definitions, a popular definition was developed in 1964 by D. U. Deere wherein it is the borehole core recovery percentage incorporating only pieces of solid core that are longer than 100 mm in length measured along the centerline of the core. As such, pieces of core that are not competent (hard and sound) should not be counted inspite of being 100 mm in length.
RQD is defined as the quotient:
lsum of pieces = Sum of length of core sticks longer than 100 mm measured along
the center line of the core ltotal core run= Total length of core run
From the RQD index the rock mass can be classified as follows:
RQD Rock mass quality
<25% very poor
25-50% Poor
50-75% Fair
75-90% Good
90-100% Excellent
Page 5 of 8
IV. RESULTS OF FIELD AND LABORATORY TESTING
The results of the borehole are generally represented below; BH 1 GWT: -9.0m
Depth,m USCS
Classification
Remarks (Relative Condition /
Consistency)
0.0 – 24.0/25.0 CH Very Soft-Stiff
25.0-34.0 SM Loose-Very Dense
V. EVALUATION / RECOMMENDATIONS FOR LATERAL EARTH PRESSURE ANALYSIS, SLOPE STABILITY and FOUNDATION DESIGN
A. Shallow Strip Foundation Using an isolated footing scheme with a minimum recommended embedment depth of 3.0m, the following values could be employed:
The above values are governed by either the limiting settlement magnitude of 25mm or shear capacity failure depending on the depth. Further, the recommended values are applicable to footing width of not more than 2.5m. B. Lateral Earth Pressure The ff. geotechnical parameters are recommended for lateral earth pressure analysis:
Embedment Depth Allowable Bearing Capacity for
Strip Foundation
3.0m 25 kPa
3.5m 35 kPa
4.0m 55 kPa
Page 6 of 8
SANDY Materials
Characteristic Very Loose Loose Medium
Dense Dense to
Very Dense
Φ (degree) 27.5 30.0 32.5 35.0-37.5
Y/ γ’ (Kn/m3) 17/9 18/10 19/11 19/11
Cu (Undrained)
(kPa)
0 0 0
0
C (kPa) 0 0 0 0
Poisson’s Ratio
(Saturated)
0.35-0.4 0.3-0.4 0.3
0.3
Poisson’s Ratio
(Unsaturated)
0.35-0.40 0.3-0.4 0.3-0.4
0.30
Ka 0.37 0.33 0.30 0.24-0.27
Kp 2.74 3.0 3.22 3.68-4.11
Es (MN/m2) 3-5 7-12 12-20 20-70
CLAYEY Materials
Characteristic Very Soft Soft Firm Medium
Stiff to Stiff Very Stiff to Very Hard
Φ (degree) 12.5 17.5 18 20.0 25-30
Y/ γ’ (Kn/m3) 16/6 17/7 18/8 18/8 19/9 to 22/12
Cu (Undrained)
(kPa)
4-8
10-25
20-40 25-50
50-200
C (kPa) 1-2 4-10 10-15 15-20 25
Poisson’s Ratio
(Saturated)
0.1-0.2
0.1-0.3
0.-0.3 0.1-0.3
0.1-0.3
Poisson’s Ratio
(Unsaturated)
0.5
0.4-0.5
0.40-0.5 0.40-0.5
0.40-0.5
Ka 0.64 0.54 0.52 0.41-0.49 0.41-0.33
Kp 1.55 1.86 1.90 2.04 2.46-3.0
Es (MN/m2) 1-2 2-5 3-5 5-20 20-70
Page 7 of 8
C. Slope Stability Possible slope stability solutions can be any of the ff methods:
Mechanically Stabilized Earth (MSE)
Soil Nailing
Rock Anchor
Sheet Pile with tie back anchors
Retaining Wall
Revetment Wall The adequate engineering measure for slope stabilization depends on the terrain, slope angle, location of critical slip circle, etc. Use of Slope Stability Charts for preliminary analysis of locating the slip circle is recommended. An example of a well-known Slope Stability Chart can be found on the Appendix of Soil Strength and Slope Stability (2005) by Duncan & Wright. However, for a detailed analysis, use of Finite Element software is recommended. Finite Element software can analyze multiple locations of critical slip surfaces in the slope and take into consideration factors such as seepage, rapid drawdown etc. A good drainage system is also recommended to control the flow of water away from the structure / slope. As excess pore water pressure may develop in the slope and more often than not, can cause slope failure. D. Mat Foundation with Underlying Soil Improvement If the above recommendation does not suffice or is impractical, mat foundation with underlying soil improvement can be employed. The following soil improvement systems can be applied:
Specialist contractors can propose detailed design based on the actual slab footprint and loading.
Page 8 of 8
LIMITATIONS The foregoing assessment and recommendations are based on the prevailing exploration and laboratory results. Should there be significant differences in the soil stratification encountered during the construction stage, the undersigned should be informed immediately so that necessary supplemental recommendations can be made.
MIGUEL DIMADURA, M CivEng Consulting Geotechnical/Sub-Structural Engineer PRC CE Reg. 59571
GEOLOGIC SETTING
A. Lithology
The study area is part of the delta of the Pampanga River which is located in the northern bounds of
the Manila Bay. The Pampanga River delta forms a shallow coastal area that is adjacent to the
Central Luzon Valley Basin. Underlying the delta are thick layers of sedimentary deposits of mud,
clay, sand and silt that originate from the Central Luzon Valley, southern slopes of the Caraballo
Mountains and the western slopes of Sierra Madre. Beneath the Quaternary deposits in the delta is
the Guadalupe Formation. The Guadalupe Formation is divided into two members – Alat
Conglomerate and Diliman Tuff. The Alat Conglomerate is the lower member which is characterized
by a sequence of conglomerate, sandstone and mudstones with approximately 200m thickness.
Diliman Tuff is the upper member and characterized by bedded deposits of fine vitric tuff, welded
pyroclastic breccias and tuffaceous sandstones. Approximate thickness of the Diliman Tuff is around
1300-2000 meters.
B. Tectonic Structures
Active faults closest to the area of interest are the West Valley Fault and East Zambales Fault. West
Valley Fault is part of the Valley Fault System which is a 135 km long dextral (right lateral strike-slip)
tectonic feature, trending north-south originating from the Angat area in Bulacan and terminating in
Tagaytay Ridge. Offset-based magnitude estimates for the West Valley fault is approximately M7.3 -
7.7 (Rimando, 2006). The trace of the West Valley Fault is located approximately 42 km southeast
from the study area .
The East Zambales Fault is a strike-slip fault present at the eastern footslopes of the Zambales Range
with 110 km length and 26 km in width (Japan International Cooperation Agency, 2004). Magnitude
estimates indicate that movement along the East Zambales Fault can generate an earthquake with
7.4 magnitude. The trace of the East Zambales Fault is located approximately 38 km north-northwest
of the study area. Figure 1 shows the location of the study area with respect to the active faults
present.
EARTHQUAKE HAZARDS
A. Ground Shaking
Ground shaking is the most immediate effect caused by earthquakes which can be accompanied by
surface rupture and displacements. The Philippine Institute of Volcanology and Seismology
(PHIVOLCS) used a deterministic model to determine the extent of ground shaking that can occur
during an earthquake event. The deterministic model was based on the work of Fukushima (1990)
which measures the horizontal peak ground acceleration at a geographical point based on its
distance from the fault rupture and wave magnitude of the earthquake event. Based on the model,
an earthquake event with 7.2 magnitude and propagated along the West Valley Fault would
generate a peak ground of acceleration of 0.20 – 0.30 g in the study area (Figure 2). An earthquake
event with magnitude 7.4 and propagated along the East Zambales Fault can generate a horizontal
peak ground acceleration of 0.15 – 0.25 g in the study area (Figure 3).
B. Liquefaction
Liquefaction is the transformation of water-saturated, unconsolidated granular material to a more
fluid like mass due to intense ground shaking. During liquefaction, sediments are compacted, losing
their strength and assuming a more liquid behavior resulting to structures built on top of liquefied
sediments to sink or tilt. The risk of liquefaction is more pronounced in areas underlain by
Quaternary Alluvium. The study area is exposed to high susceptibilities of liquefaction due to the
unconsolidated layers of sediments that underlie it.
Figure 1. Location map of the study area with respect to the East Zambales Fault and the West Valley Fault
Figure 2. Distribution of horizontal peak ground acceleration values caused by a Magnitude 7.2 earthquake event generated along the West Valley Fault. Map modified from PHIVOLCS (n.d)
Study Area
East Zambales Fault
West Valley Fault
Study Area
References:
Fukushima, Y., Tanaka T., 1990, A New Attenuation Relation for Peak Horizontal Acceleration of Strong
Peña, R., & Aurelio, M. (2005). Geology and Mineral Resources of the Philippines. Quezon City: Department of Environment and Natural Resources.
Philippine Institute of Volcanology and Seismology (Cartographer). (n.d). Rapid Earthquake Damage Assessment System (REDAS) [map].
Rimando, R. (2006). Neotectonics of Marikina Valley Fault System and Tectonic Framework of
Structures in Northern and Central Luzon, Philippines. Tectonophysics, 17-38.
Study Area
Figure 3. Distribution of horizontal peak ground acceleration values caused by a Magnitude 7.4 earthquake event generated along the East Zambales Fault. Map modified from PHIVOLCS (n.d)
BOREHOLE LOCATION PLANDRAWN NOT TO SCALE
CONTROL NUMBER
DRILLED BY
DATE STARTED
DATE FINISHED
WEATHER
ENCODED BY
0.00
#4 100.00 LL= 65.80
#10 100.00 PL= 31.14
#40 94.93 PI= 34.66
1.50 1.50 SPT NO REC SS-1 - #200 86.29
#4 100.00 LL= 65.90
#10 100.00 PL= 31.73
#40 93.00 PI= 34.17
3.00 3.00 SPT NO REC SS-2 - #200 82.02
#4 100.00 LL= 64.20
#10 100.00 PL= 31.00
#40 94.82 PI= 33.20
4.50 4.50 SPT 0.35 SS-3 - 5 5 4 9 #200 86.06
#4 100.00 LL= 63.70
#10 100.00 PL= 31.35
#40 94.35 PI= 32.35
6.00 6.00 SPT 0.35 SS-4 - 5 4 3 7 #200 85.09
#4 100.00 LL= 62.80
#10 100.00 PL= 30.77
#40 95.45 PI= 32.03
7.50 7.50 SPT NO REC SS-5 - #200 87.03
#4 100.00 LL= 64.70
#10 100.00 PL= 31.42
#40 94.92 PI= 33.28
9.00 9.00 SPT NO REC SS-6 - #200 86.02
#4 100.00 LL= 69.20
#10 100.00 PL= 32.46
#40 94.38 PI= 36.74
10.50 10.50 SPT NO REC SS-7 - #200 84.37
#4 100.00 LL= 66.20
#10 100.00 PL= 31.68
#40 95.97 PI= 34.52
12.00 12.00 SPT NO REC SS-8 - #200 89.09
#4 100.00 LL= 67.30
#10 100.00 PL= 32.04
#40 94.31 PI= 35.26
13.50 13.50 SPT NO REC SS-9 - #200 85.24
#4 100.00 LL= 66.30
#10 100.00 PL= 32.09
#40 94.25 PI= 34.21
15.00 15.00 SPT NO REC SS-10 - #200 85.00
#4 100.00 LL= 67.40
#10 100.00 PL= 32.04
#40 94.35 PI= 35.36
16.50 16.50 SPT NO REC SS-11 - #200 85.09
#4 100.00 LL= 69.50
#10 100.00 PL= 32.04
#40 92.67 PI= 37.46
18.00 18.00 SPT NO REC SS-12 - #200 82.46
#4 100.00 LL= 68.60
#10 100.00 PL= 32.00
#40 93.46 PI= 36.60
19.50 19.50 SPT NO REC SS-13 - #200 85.00
#4 100.00 LL= 63.70
#10 100.00 PL= 31.13
#40 93.75 PI= 32.57
21.00 21.00 SPT NO REC SS-14 - #200 83.40- -
COHESIVE SOILS COHENSIONLESS SOILS
N - VALUES CONSISTENCY N - VALUES CONSISTENCY
CH-Silty CLAY MH-Clayey SILT 0 - 2 VERY SOFT 0 - 4 VERY LOOSE