Kingdom of Cambodia National Region KingNational Polytechnic Institute of CambodiaFaculty of Civil Engineering Paper research of piles foundationIn Phnom Penh capital of Cambodia Phnom Penh October 11, 2011
This present paper research was prepared by Mr. Sieng PEOU Master Scienceof geotechnical engineering and lecturer of geotechnical engineering in departmentGeo-resources and Geotechnical Engineering of Institute of Technology of Cambodia(ITC).Acknowledgements I would like to firstly express my deepest thanks and gratitude to Dr. SuenSAMBAT deputy director of International University for his kindness, valuablesupport, encouragement, and helpful guidance of this paper research. He alwaysshared his valuable time to cooperatively discuss my research when I needed his help.I consider it to be great fortune to have had the opportunity to work with him and alsothe best experience in conducting the research. Furthermore, I would like to extend my grateful thanks to Mr. Iv MONY thedirector of Research and Design Enterprise for his helpfulness and kindness providedall possibility for complete this research. My sincere gratitude is extended to Dr. OM Romony Director of Institute ofTechnology of Cambodia, who always supported and encourages me to do thisresearch. Moreover, my great thanks are given to all lecturers of Department of Geo-resources and Geotechnical Engineering for their motivation, care, help, discussionand friendship. And at last I would like to thanks to Ministry of Land and Management ofCambodia and Research & Design Enterprise, who supported the fund for thisresearch.Abstract In the last time the driven pile and bored pile foundation are widely used inCambodia. And for calculation the bearing capacity of bored pile foundation we have a lot ofequation for resolve it by using soil parameter from laboratory testing and by using in situ testlike static cone penetration test, dynamic cone penetration test, pressiometer test and standardpenetration SPT. The problem for us is the inability to take undisturbed sample at the greater depth likefor the sandy soil, so the capacity of our laboratory can not provide sufficiently soil data forcalculates the bearing capacity of pile foundation. So we need equation and safety factorsuitable for the sub-soil condition in Cambodia by using index SPT. For verifying the bearing capacity of bored pile and driven pile foundation we needstatic pile load test. The research was done in the construction of the Ministry of Land and Managementof Cambodia for bored pile and in Sport City, street No211, Sangkat Vealvong, Khan 7Makara, Phnom Penh city for driven pile.Keywords Bored pile foundation, driven pile, Standard Penetration Test (SPT), pile load test,bearing capacity.
Introduction The bearing capacity of driven pile and bored pile foundation is the problem veryimportant in Cambodia. The level of research on condition of geotechnical engineering inCambodia is not yet sufficiently for estimation the bearing capacity of soil foundation in thiscountry. In this research we try to find suitable equation and safety factor of bored pilefoundation in Phnom Penh capital of Cambodia. The location of research is located in PhnomPenh Capital of Kingdom of Cambodia. For verifying the bearing capacity of driven pile and bored pile foundation we needstatic pile load test. For bored pile the test was done in the construction of the Ministry of Land andManagement of Cambodia. For driven pile the test was done in Sport City, street No211, Sangkat Vealvong,Khan 7 Makara, Phnom Penh city. I-Research on Bored pile foundation:The test divided in two steps: -Step 1: Soil boring and SPT testing in the boring hole. -Step 2: Static pile load test on bored pile foundation by Quick MaintainedLoad.For step 1 we bored 5 boreholes with the depth 35.00m and done the SPT test every1.50m. We also collected the soil sample for testing in the laboratory condition. The soil investigation was carried out on August, 10, 2009.I-1-Soil boring and take soil sample for testing in laboratory condition:I-1-1-Field work Boring and take the undisturbed and disturbed sample Standard penetration test in boring hole Shear vane test in boring hole Pocket penetration test on undisturbed sample Pocket shear vane test on undisturbed sampleI-1-2-Laboratory testing Water content Atterberge limits Specific gravity Soil particle size Unconfined compression test Direct shear test Consolidation testThe testing-procedure was conducted in accordance with ASTM Standard andclassified soil by USCS.
I-2-SPT testing in the boring hole: Standard Penetration Test was carried out 1.50m intervals inside the eachboring hole. A standard split spoons of 50.8mm diameter with a ball check valve onthe top and harden steel cutter. A Standard spilt spoon was installed and drives intothe soil by a 63.5kg automatically drop hammer falling freely from a fixed height of760mm along a guide rod. The blow counts defined for each 150mm penetration of the seating drive. Thetotal penetration of the spoon is 450mm and the numbers of blow N-value for last300mm. Penetration was recorded as the N-value of the soil stratum encounteredwhich indicated the relative density of non-cohesive soil as well the consistency of thecohesive soil.I-3- SAMPLING I-3-1-Undisturbed samples: Undisturbed samples were taken in the naturalstate of the soil from firm to stiff clay and sandy clay. The undisturbed samples weretaken by thin wall tube sampler in the natural state. I-3-2Disturbed samples: The disturbed samples were taken at a rate of 1.5mand all strata in the each borehole. The disturbed samples were also collected in softto stiff clay and sandy soil. The relation between S.P.T result and Consistency for Clay, Silt, Clayed-Silt and Silty-Clay (Cohesion Soils) Table 1 S.P.T N Value (blows/ 300mm) CONSISTENCY 0 to 2 Very soft 2 to 4 Soft 4 to 8 Medium Stiff 8 to 15 Stiff 15 to 30 Very Stiff 30 over Hard The Relation between S.P.T Result and Relative Density For Sand and Gravel (Cohesion less Soil) Table 2 S.P.T N Value (blows/ 300mm) RELATIVE DENSITY Less than 4 Very loose 4 to 10 Loose 10 to 30 Medium dense 30 to 50 Dense Over 50 Very dense
I-4-GROUND CONDITION AND SOIL PROPERTIES For this site the ground condition from the ground surface to 35.00m depthsconsisted of filling process of Mekong River was in 4th Era (Young alluvium). Thesoil condition encountered on boreholes has been into strata as follows: BOREHOLE No 5Stratum N-value No Blows /300mm Description of soil strata 1 - Made ground, encountered from top to 2.00m depths. 2 - Brown stiff Lean CLAY, encountered from 2.00m to 4.20m. N-12 3 - Grey medium dense Fine SAND, encountered from 4.20m to 5.30m. N-16 4 - Grey loose Fine SAND, encountered from 5.30m to 8.50m. N-9; N-10 - Grey medium dense Fine SAND, encountered from 8.50m to 5 N-29 10.30m. 6 - Yellow dense Clayey SAND, encountered from 10.30m to 13.50m. N-49; N-43 - Grey very stiff Lean CLAY with sand, encountered from 13.50m to 7 N-28 14.60m. 8 - Yellow very dense Fine SAND, encountered from 14.60m to 15.80m. N-69 9 - Grey dense Fine SAND, encountered from 15.80m to 17.70m. N-41 10 - Yellow very stiff Fat CLAY, encountered from 17.70m to 20.50m. N-24; N-25 11 - Yellow dense medium SAND, encountered from 20.50m to 21.70m. N-50 12 - Yellow hard Lean CLAY, encountered from 21.70m to 23.70m. N-37 13 - Yellow dense medium SAND, encountered from 23.70m to 25.00m. N-41 14 - Yellow dense Clayey SAND, encountered from 25.00m to 28.20m. N-47; N-34 - Yellow very dense Clayey SAND, encountered from 28.20m to 15 N-55; N-61 30.70m. - Yellow very hard Fat CLAY with sand, encountered from 30.70m to 16 N-62; N-69; N- 35.00m. 74
On basis of field observation, it appears reasonable to standardize the field penetration number as a function of the input driving energy and its dissipation around the sampler into the surrounding soil, or N . H . B . S . R N 60 60
Based on recommendation by Seed et al.(1985) and Skempton(1986)1-variation of HCountry Hammer type Hammer release HJapan Donut Free fall 78 Donut Rope and pulley 67United State Safety Rope and pulley 60 Donut Rope and pulley 45Argentina Donut Rope and pulley 45China Donut Free fall 60 Donut Rope and pulley 50
2-variation of B Diameter B mm In. 60-120 2.4-4.7 1 150 6 1.05 200 8 1.153-variation of sVariable sStandard sampler 1With liner for dense sand and clay 0.8With liner for loose sand 0.94-variation of RRod length Rm ft>10 >30 16-10 20-30 0.954-6 12-20 0.850-4 0-12 0.75
I-5-Bored pile bearing capacity from SPT : We used the equation Shioi and Fukui (1982) for calculation the End BearingCapacity of bored pile foundation. And for calculation the skin friction we were usedtwo methods, the equation Findley (1984) and Shioi and Fukui (1982) and theequation Wrigth and Reese (1982):I-5-1-End bearing capacity:-After Shioi and Fukui (1982)1-for coarse grained soilqP=100N60(KPa)2-for fine grained soilqP=150N60(KPa)So Qp=qP.AP(KN)I-5-2-Skin friction For coarse grained soil:-After Findley (1984) and Shioi and Fukui(1982) : qf=N60(KPa)-After Wright and Reese (1979) :qf=3.3N60(KPa)I-5-3-Skin friction For fine grained soil:-After Decourt (1982) :qf=10+3.3N60(KPa) The results after testing shown as follow: 1-If we choose the equation Findley (1984) and Shioi and Fukui(1982) for calculate the skin friction we can find the ultimate bearing capacity for bored pile with dimension diameter D=1.00m and 31.00 m length: QU=9900KN. So for safety factor 2.0, we have allowable bearing capacity Qall=4950KN 2-If we choose the equation Wrigth and Reese (1982) for calculate the skinfriction we can find the ultimate bearing capacity for bored pile with dimensiondiameter D=1.00m and 31.00 m length: QU=14726KN. So for safety factor 3.0, we have allowable bearing capacity Qall=4909KN
For step 2 we prepared the static pile load test by Quick Maintained Loadmethod.I-6-Pile load test The pile load test was carried out on October, 23, 2009.-for verifying the bearing load for bored pile with D=1.0m and L=31.0m.-for comparing the equation were used in the report of soil investigation. Pros versus Cons of load testing a pile: -Load testing is the most accurate way to determine the ultimate compressive andtensile capacities for deep foundations. -Load testing is expensive and time consuming.I-6-1-The testing procedure: The test load shall be conforming to the Modified ASTM D 1143/D1143M-07Item8.1.3 Procedure B with the load sequence, in percent of design load as shownbellows:1st cycle0% --> 25%- ->50%-- >75%- -> 100%(*)- -> 50%-->25%- -> 0%(**)2nd cycle0%- -> 25% -->50%-- >75%- -> I00%- -> 125%- -> 150%- -> 175%-- >200%(*)- ->l50%-->100%- -> 50%- -> 0%(**).
I-6-2-Condition test: -Maintain each load in cycle 1 and 2 until the rate of settlement is less than0.25mm./hr but not more than 2 hours which ever occurs first. -Maintain maximum test load( *) in cycle 1 and 2 for 12 hours if the rate ofsettlement over a one-hour period is not greater than 0 .25 mm./hr, otherwise maintainthe maximum test load for 24 hours. -Released the test load in cycle 1 and 2 every 1 hour and maintain zero load(**) until recovery rebound stop but not more than 12 hours, -Take reading of time Load and settlement in cycle1 and 2. Record them justat 0, 5,10,15,20,40,60,80,100 and 120 minutes and every 1 hour for the next 10 hoursand every 2 hours thereafter.I-6-3-Test result: The interpretation of test results shall comprise of: -Pile Description -Tabulation of test data: time, load and movement of test pile head. -Load-Settlement curve -Time-Load curve -Time-Settlement curve -Conclusion - etc..I-6-4-Final result: The final result of pile testing is presented in the table as follow: Q-apply load (KN) -final settlement (mm) Q (mm) 0 0 1065 0.69 2130 1.69 3195 2.65 4260 3.91 5320 5.35 6390 6.55 7455 10.05 8520 18.29
I-6-7-Offset limit load straight line OC=3.8+D/120 After the calculation the ultimate bearing capacity of bored pile foundationfrom pile load test result by using Davisson’s method, we find 0.9Qu=8850KN, so Qu=9833KN For pile load test we take the safety factor FS=2, so Qall=4917KN
I-6-8-Summaries of research Method Qu FS Qall (KN) (KN) Pile load test result 9833 2 4917 Equation Wright and 14726 3 4909 Reese Equation Findley and 9900 2 4950 Shioi and FukuiI-6-9-Conclusion The conclusion after the study is presented as follow: - The equation Wright and Reese (1979) find the same result as pile load testwhen we take safety factor FS=3. - The equation Findley (1984) and Shioi and Fukui (1982) find nearly thesame result as pile load test when we take safety factor FS=2.
II-Research on Driven pile foundation:The test also divided in two steps: -Step 1: Soil boring and SPT testing in the boring hole. -Step 2: Verified pile bearing capacity by pile driven equation -Step 3: Static pile load test on bored pile foundation by Quick MaintainedLoad. For step 1 we bored 8 boreholes with the depth 15.00m and done the SPT testevery 1.50m. We also collected the soil sample for testing in the laboratory condition. The soil investigation was carried out on November, 07, 2007: 1-Soil boring and take soil sample for testing in laboratory condition. 2- SPT testing in the boring hole. BOREHOLE Nº 2Stratum 1: Made ground, present from 0.00m to 2.00m depths.Stratum 2: Brown soft sandy clay, present from 2.00m to 5.20m depths.Stratum 3: Yellow stiff lean clay with sand, present from 5.20m to 7.00m depths.Stratum 4: Loose clayey fine sand, present from 7.00m to 8.00m depths.Stratum 5: Medium dense clayey silty fine sand, present from 8.00m to 9.80m depths.Stratum 6: Grey dense clayey fine sand, present from 9.80m to 14.20mStratum 7: Yellow stiff lean clay, present from 14.20m to 15.00m depths.
II-1-Driven pile bearing capacity from SPT:We used the equation Decourt (1982) and Matin et al(1987) for calculation the EndBearing Capacity of driven pile foundation:II-1-2-End bearing capacity:1-for coarse grained soil by Decourt (1982)qP=400N60(KPa)2-for Clay by Matin et al(1987) qP=200N60(KPa)3-for Silt and sandy Silt by Matin et al (1987)qP=350N60(KPa) And for calculation the skin friction we were used equation Meyerhof (1956) Decourt(1982):II-1-3-Skin friction:-Meyerhof equation (1956) for Sand:qf=2N60(KPa)-Decourt equation (1982) for mixed soil:
qf=10+3.3N60(KPa)-Shioi and Fukui equation (1982) for Clay :qf=10N60(KPa) The results after testing shown as follow:After the study we obtained the result as follow: 1- The ultimate bearing capacity for driven pile with dimension diameterB=0.30m and 11.00 m length: QU=1358.88KN. So for safety factor 4.0, we haveallowable bearing capacity Qall=339.7KNFor step 2 we verified the pile berating capacity by pile driven equation:II-Pile bearing capacity from pile driven method:II-1-Modified ENR equations EWR h WR n 2WPQu ( )( ) S C WR WPII-2-Michigan state highway commission equations 1,25EH E WR n 2WPQu S C WR WPII-3-Danish equations EH EQu EH E L S 2 AP EPII-4-Pacific Coast Uniform Building Code equations W nWP ( EH E ) R W W Qu R P Qu L S AP E P
II-5-Pile driven data E-hammer efficiency=0.8 Ep- elastic modulus of the pile=21000000KPa h-height of fall of the ram=0.8 M S-penetration of the pile per hammer blow=0.0083 (M) WR-Weight of the ram=50 KN WP-weight of the pile=24.75 KN n- Coefficient of restitution between the ram and the pile cap n=0.4 exceptequation pacific coast uniform building code n=0.1 C=0.00254 M Hammer type Efficiency,E Single and double acting hammers 0.7-0.85 Diesel hammers 0.8-0.9 Drop hammers 0.7-0.9 Pile material Coefficient of restitution n Cast iron hammer and concrete pile 0.4-0.5without cap Wood cushion on steel pile 0.3-0.4 Wooden pile 0.25-0.3
II-6-Results of pile driven bearing capacity from pile driven equationsMethod Ultimate bearing Safety Allowable load (KN) factor bearing load (KN)Modified ENR equation 2124.46 6 354.076Michigan state highway 2655.57 6 442.595commission equationsDanish equations 1779.43 5 355.886Pacific Coast Uniform 1375.09 4 343.773Building Code equationsFor step 3 we prepared the static pile load test by Quick Maintained Load method andwe obtained the result as follows: The pile load test was carried out on January, 20, 2008:1-for verifying the bearing load of driven pile with B=0.3m and L=11.0m.2-for comparing the equation were used in the report of soil investigation.II-7-Result of pile load testingThe final result of pile testing is presented in the table as follow:Q-apply load (KN)-final settlement (mm) Q (mm) 0 0 83.5 0.69 167 1.69 246.9 2.65 330.4 3.91 493.8 5.35 577.3 6.55 660.8 10.05 740.6 18.29
II-10-Offset limit load straight line OC=3.8+D/120After the calculation the ultimate bearing capacity of bored pile foundation from pileload test result by using Davisson’s method, we find 0.9Qu=600KN, so Qu=666.66KNFor pile load test we take the safety factor FS=2, so Qall=333.33KN
II-11-Summaries of research Method Qu FS Qall (KN) (KN)Modified ENR equation 2124.46 6 354.076Michigan state highway 2655.57 6 442.595commission equationsDanish equations 1779.43 5 355.886Pacific Coast Uniform Building 1375.09 4 343.773Code equationsPile load test result 666.66 2 333.33SPT test result 1358.88 4 339.70According to this research we check the pile driven in Phnom Penh area, and weobtained the results as follows: Result pile driven test in KOKI district, Phnom Penh. Pile length L=21m and pile size B=0.3m Method Ultimate Safety Allowable bearing load factor bearing load (KN) (KN) SPT 1356.24 4 339.1 Modified E NR equation 2511.94 6 418.65 Michigan state highway 3139.93 6 523.32 commission equations Danish equations 1745.45 5 349.09 Pacific Coast Uniform 1067.78 4 266.94 Building Code equations
Result pile driven test in Vealsbov district, Phnom Penh. Pile length L=21m and pile size B=0.3m Method Ultimate Safety Allowable bearing load factor bearing load (KN) (KN) SPT 1316.64 4 329.2 Modified E NR equation 2466.89 6 411.14 Michigan state highway 3083.61 6 513.93 commission equations Danish equations 1787.73 5 357.5 Pacific Coast Uniform 1154.63 4 288.65 Building Code equationsII-12-ConclusionThe conclusion after the study is presented as follow: 1- If we choose method SPT for determine the bearing capacity of driven pilefoundation in Phnom Penh area we need the safety factor of 4. 2-After testing on driven pile in Phnom Penh area, we can find that: -for short pile all the driven equation find nearly the same results. -for long pile, the Danish equation is always verified with SPTmethod but for another equation showed very varied results. 3- This research is limited for data pile load test in Phnom Penh city only. This research paper prepared by Prof. Sieng PEOU Master science of geotechnical engineering Lecturer of geotechnical engineering in department Geo-resources and Geotechnical Engineering Institute of Technology of Cambodia Email: email@example.com Tel:(855)11 874 974 Phnom Penh October, 11, 2011
Reference:1-Principles of foundation engineering Sixth Edition Braja M. Das 20072-Soil mechanics and foundations First Edition Muni Budhu 20003-Results Soil investigation done by Research and Design Enterprise4-Results Static pile load test done by Innovation Engineering Service5-Davisson, M. T., “High capacity piles". Proceedings of Lecture Series onInnovations in Foundation Construction, American Society of Civil Engineers, ASCE6- Emerging Technologies in Structural EngineeringProc. of the 9Th Arab Structural Engineering Conf., Nov. 29 - Dec. 1, 2003, AbuDhabi, UAE