Axial and Lateral Efficiency of Tapered Pile Groups in Sand Using Mathematical and Three-Dimensional Numerical Analyses
Publication: Journal of Performance of Constructed Facilities
Volume 36, Issue 1
Abstract
This study presents a new mathematical equation for calculating the pile group efficiency in cohesionless soil under combined axial and lateral loading conditions, considering the tapering angle effect. Based on the mathematical definition of the pile group efficiency, analytical correlations are developed. The tapering effect is considered by developing a new geometry coefficient for efficiency associated with the shaft vertical bearing component of tapered piles. In addition, a simplified mathematical equation is developed for predicting the group interaction factor as a function of pile spacing, number of piles in the group, diameter of the cylindrical reference pile, tapering angle, and pile slenderness ratio. On the other hand, an array of three-dimensional numerical analyses is performed for modeling same-volume single bored piles and pile groups with various arrangements to capture the accuracy of the proposed mathematical equation. The hardening soil constitutive model is adopted for the modeling of piles in loose sand. Subsequently, the load-displacement diagrams of single piles, as well as pile groups, are obtained. The bearing capacities of straight-sided and tapered bored piles are then calculated and compared using a definite settlement criterion. By computing the various bearing-capacity components, group efficiencies can be attained from both numerical and mathematical analyses. The results indicate an acceptable agreement between both analyses. Finally, the developed equation can predict the pile group efficiency incorporating the tapering angle and other influencing parameters as a novel and simple relationship under simultaneous axial and lateral loading conditions.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
All data generated or used during the study appear in the published article. Authors will provide any other information required on request.
References
ASCE. 1984. Practical guidelines for the selection, design and installation of piles. Reston, VA: ASCE.
Bolin, H. 1941. “The pile efficiency formula of the uniform building code.” Build. Standards Monthly 10 (1): 4–5.
Bowles, L. E. 1996. Foundation analysis and design. New York: McGraw-Hill.
Brinkgreve, R., W. Swolfs, and E. Engine. 2002. Plaxis users manual. Rotterdam, Netherlands: A.A. Balkema.
Brown, D. A., C. Morrison, and L. C. Reese. 1988. “Lateral load behavior of pile group in sand.” J. Geotech. Eng. 114 (11): 1261–1276. https://doi.org/10.1061/(ASCE)0733-9410(1988)114:11(1261).
Cairo, R., and E. Conte. 2006. “Settlement analysis of pile groups in layered soils.” Can. Geotech. J. 43 (8): 788–801. https://doi.org/10.1139/t06-038.
Chellis, R. D. 1969. Pile foundations. 2nd ed. New York: McGraw-Hill.
Das, B. 2004. Principles of foundation engineering. Pacific Grove, CA: Brooks/Cole-Thomson Learning.
Feld, J. 1943. “Discussion on friction pile foundations.” Trans. Am. Soc. Civ. Eng. 108 (1): 756–757. https://doi.org/10.1061/TACEAT.0005589.
Hanna, A. M., G. Morcous, and M. Helmy. 2004. “Efficiency of pile groups installed in cohesionless soil using artificial neural networks.” Can. Geotech. J. 41 (6): 1241–1249. https://doi.org/10.1139/t04-050.
Hataf, N., and A. Shafaghat. 2015a. “Numerical comparison of bearing capacity of tapered pile groups using 3D FEM.” Geomech. Eng. 9 (5): 547–567. https://doi.org/10.12989/gae.2015.9.5.547.
Hataf, N., and A. Shafaghat. 2015b. “Optimizing the bearing capacity of tapered piles in realistic scale using 3D finite element method.” Geotech. Geol. Eng. 33 (6): 1465–1473. https://doi.org/10.1007/s10706-015-9912-6.
Khan, M. K., M. H. El Naggar, and M. Elkasabgy. 2008. “Compression testing and analysis of drilled concrete tapered piles in cohesive-frictional soil.” Can. Geotech. J. 45 (3): 377–392.
Kishida, H. 1965. “Bearing capacity of pile groups under eccentric loads in sand.” In Vol. 2 of Proc., 6th ICSMFE, 270–274. London: International Society for Soil Mechanics and Geotechnical Engineering.
McVay, M., R. Casper, and T.-I. Shang. 1995. “Lateral response of three-row groups in loose to dense sands at 3D and 5D pile spacing.” J. Geotech. Eng. 121 (5): 436–441. https://doi.org/10.1061/(ASCE)0733-9410(1995)121:5(436).
Poulos, H. 1968. “Analysis of the settlement of pile groups.” Géotechnique 18 (4): 449–471. https://doi.org/10.1680/geot.1968.18.4.449.
Poulos, H. G. 1971. “Behavior of laterally loaded piles: I-single piles.” J. Soil Mech. Found. Div. 97 (5): 711–731. https://doi.org/10.1061/JSFEAQ.0001592.
Poulos, H. G. 1979. “Group factors for pile-deflection estimation.” J. Geotech. Geoenviron. Eng. 105 (15032): 1489.
Poulos, H. G., and E. H. Davis. 1980. Pile foundation analysis and design. Sydney, Australia: Univ. of Sydney.
Randolph, M. 1994. “Design methods for pile group and piled rafts.” In Proc., 13th Int. Conf. on SMFE. New Delhi, India: Oxford and IBH Publishing.
Rao, N. K. 2010. Foundation design: theory and practice. New York: Wiley.
Rose, A. V. 2012. Behavior and efficiency of perimeter pile groups. London: City Univ. London.
Ruesta, P. F., and F. C. Townsend. 1997. “Evaluation of laterally loaded pile group at Roosevelt Bridge.” J. Geotech. Geoenviron. Eng. 123 (12): 1153–1161. https://doi.org/10.1061/(ASCE)1090-0241(1997)123:12(1153).
Sayed, S. M., and R. M. Bakeer. 1992. “Efficiency formula for pile groups.” J. Geotech. Eng. 118 (2): 278–299. https://doi.org/10.1061/(ASCE)0733-9410(1992)118:2(278).
Schanz, T., P. Vermeer, and P. Bonnier. 1999. “The hardening soil model: formulation and verification.” In Beyond 2000 in computational geotechnics, 281–296. Rotterdam, Netherlands: A.A. Balkema.
Seiler, J., and W. Keeney. 1944. “The efficiency of piles in groups.” Wood Preserving News 22 (11): 109–118.
Shafaghat, A., and H. Khabbaz. 2020a. “Numerical evaluation of bearing capacity of step-tapered piles using PY curves analysis.” In Advancements in geotechnical engineering, 200–212. New York: Springer.
Shafaghat, A., and H. Khabbaz. 2020b. “Recent advances and past discoveries on tapered pile foundations: A review.” Geomech. Geoeng. 15: 1–30. https://doi.org/10.1080/17486025.2020.1794057.
Shafaghat, A., H. Khabbaz, and B. Fatahi. 2021a. “Analytical and numerical approaches to attain the optimum tapering angle for axially loaded bored piles in sandy soils.” Int. J. Geomech. 21 (7): 04021099. https://doi.org/10.1061/(ASCE)GM.1943-5622.0002056.
Shafaghat, A., H. Khabbaz, and B. Fatahi. 2021b. “Developing an efficiency equation for tapered pile groups in sand using mathematical and numerical analyses.” In Civil infrastructures confronting severe weathers and climate changes conference, 16–30. Cham, Switzerland: Springer.
Shafaghat, A., H. Khabbaz, S. Moravej, and Ah Shafaghat. 2018. “Effect of footing shape on bearing capacity and settlement of closely spaced footings on sandy soil.” Int. J. Geotech. Geol. Eng. 12 (11): 676–680. https://doi.org/10.5281/zenodo.2021705.
Shibata, T., A. Yashima, and M. Kimura. 1989. “Model tests and analyses of laterally loaded pile groups.” Soils Found. 29 (1): 31–44. https://doi.org/10.3208/sandf1972.29.31.
Tejchman, A. 1973. “Model investigations of pile groups in sand.” J. Soil Mech. Found. Div. 99 (2): 199–217. https://doi.org/10.1061/JSFEAQ.0001852.
Terzaghi, K., R. B. Peck, and G. Mesri. 1996. Soil mechanics in engineering practice. New York: Wiley.
Tuan, P. 2016. “A simplified formula for analysis group efficiency of piles in granular soil.” Int. J. Sci. Eng. Res. 7 (7): 15–21.
Vesic, A. 1980a. “Predicted behavior of piles and pile group at the Houston site.” In Proc,. Pile Group Prediction Symp. College Park, MD: Univ. of Maryland.
Vesic, A. S. 1967. A study of bearing capacity of deep foundations. Atlanta: Georgia Institute of Technology.
Vesic, A. S. 1980b. “Analysis of pile group behaviour predictions for the Houston site.” In Proc., Pile Group Prediction Symp. College Park, MD: Univ. of Maryland.
Vesić, A. 1969. “Experiments with instrumented pile groups in sand.” In Performance of deep foundations. West Conshohocken, PA: ASTM.
Zhao, Y. J., and H. K. Stolarski. 1999. Stability of pile groups. Minneapolis: Univ. of Minnesota.
Information & Authors
Information
Published In
Journal of Performance of Constructed Facilities
Volume 36 • Issue 1 • February 2022
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Apr 13, 2021
Accepted: Sep 16, 2021
Published online: Nov 3, 2021
Published in print: Feb 1, 2022
Discussion open until: Apr 3, 2022
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.