Numerical Analysis of Pile-Soil Interface Strength Properties Effects on the Lateral Stiffness of p-y Curves

Document Type : Research Note

Authors

• hassan sharafi
• yazdan shams maleki

razi university

10.22067/civil.v1i30.42709

Abstract

Investigation of lateral bearing capacity of piles under lateral loading in the vicinity of soil slopes and level ground is one of the interesting issues in the engineering of the deep foundations in recent decades. In the meantime, the estimation of lateral stiffness of soil layers, coefficient of soil reaction, ks, is an old challenge on the basis of the creation of empirical (testing) and theoretical p-y curves. In this paper, we attempt to estimate lateral soil stiffness in the length of concrete piles in various depths in sloped ground and level ground and in the all type of soils, including cohesive soil, frictional (granular) soil and mixed soil, i.e. c-φ soil with the aid of numerical analysis in three dimensional finite difference software, Flac3D. For the purpose of estimating lateral soil stiffness, Ki, in different depths by means of this numerical method, the p-y curves have been derived in several depths in the length of concrete pile with circular section under static lateral loading up to the threshold of the yielding of soil materials. The empirical relationship established between soil lateral stiffness Ki and the effective dimensionless parameters on the Ki in general is calculated as a six order polynomial, and this six order polynomial reduces to a fourth order polynomial for the cohesion component of the soil. At the end of the paper, some well documented lateral loading tests by the present numerical method have been investigated for validation of the numerical method of derivation of the p-y curves and pile-head load deflection curves, H-y curves have been calculated and are compared with other results obtained by other researchers and methods. There are good agreements between test results and the results obtained from the numerical method presented in this paper.

Keywords

• Pile under Lateral Loading
• Soil Lateral Stiffness, p-y Curves
• Three Dimensional Finite Difference Analysis
• Empirical Relationships

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References

1. Winkler, E., "Theory of Elasticity and Strength", Prague: Dominicus, (1867).

2. سازمان امور مقررات ملی ساختمان ایران، «مبحث هفتم مقررات ملی ساختمان: پی و پی‌سازی»، ویرایش سوم، (1392).

3. Itasca, FLAC3D, "Fast Lagrangian Analysis of Continua", version 3.00-261: user’s and theory manuals. Minneapolis: Itasca Consulting Group, Inc., (2002).

4. Reese, L.C., Van Impe, W.F., "Single Piles and Pile Group under Lateral Loading", Rotterdam: A. A. Balkema publishers, (2007).

5. Georgiadis, K.,Georgiadis, M., "Un-drained Lateral Pile Response in Sloping Ground", J Geotech Geoenviron Eng , ASCE, Vol. 136 (11), PP. 1489-500, (2010).

6. Georgiadis, K., and Georgiadis, M., "Development of p-y Curves for Undrained Response of Piles near Slopes", Journal Computer and Geotechnic, Vol. 40, PP. 53-61, (2012).

7. Brinkgreve, R.B.J., Swolfs, W.M., "Plaxis 3D Foundation Version 2 User’s Manual", Plaxis BV, Netherlands, (2007).

8. Comodromos, E. M., Papadopoulou, M. C., "Explicit Extension of the p-y Method to Pile Groups in Cohesive soils", J Computers and Geotechnics, Vol. 47, PP. 28-41, (2013).

9. Comodromos, EM., Papadopoulou, MC., "On the Response Prediction of Laterally Loaded Fixed - head Pile Groups in Sands", Journal Computers and Geotechnics, Vol. 37, PP. 903-41, (2010).

10. Nimityongskul, N., Barker, P., Ashford, SA., "Effects of Soil Slope on Lateral Capacity of Piles in Cohesive and Cohesionless Soils", Final report of a research project funded by Caltrans under facilities contract No. 59A0645, The Kiewit center for infrastructure and transportation ,Oregon state university, USA, March (2012).

11. Poulos, HG., Davis, EH., "Pile Foundation Analysis and Design", John Wiley, New York, (1980).

12. شمس ملکی، یزدان، «بررسی عددی شمع‌های قائم تحت بارجانبی و استخراج منحنی‌های طراحی p-y در حالات خاص»، پایان‌نامۀ کارشناسی ارشد، دانشکدۀ فنی مهندسی، دانشگاه رازی کرمانشاه، (مهرماه 1392).

13. Sharafi, H., Shams Maleki, Y., "p-y Curves in Soils by Considering Pile-soil Interface Properties Effects", Electerical Journal of Geotechnical Engineering, EJGE, Vol. 19(D), PP. 955-970, (2014).

14. Sharafi, H., Shams Maleki, Y., Karimpour-Fard, M., "Three Dimensional Finite Difference Modeling of Static Soil-pile Interactions to Calculate p-y Curves in Pile-Supported Slopes", Arab J Geosci, Springer AJGS, DOI 10.1007/s12517-015-2051-9, PP:1-16 (2015).

15. Matlock, H., "Correlations for Design of Laterally Loaded Piles in Soft Clay", Proceedings of 2nd Annual Offshore Technology Conference, Paper No. OTC 1204, Houston, Texas, PP. 577-9, (1970).

16. Reese, LC., Welch, RC., "Lateral Loading of Deep Foundations in Stiff Clay", Journal Geotechnical Engineering Division, ASCE, Vol. 101(7), PP.633-49, (1975).

17. Price, G., Wardle, I. F., "Lateral Load Tests on Large Diameter Bored Piles", Contractor report, Transport and road research laboratory, Department of transport, Crowthorne; Berkshire, England, PP. 45-6, (1987).

18. Ismael, NF., "Behavior of Laterally Loaded Bored Piles in Cemented Sands", Journal Geotech Engrg , ASCE, Vol. 116(11), PP. 1678-99, (1999).

19. Bhushan, K., Haley, SC, Fong, PT., "Lateral Load Tests on Drilled Piers in Stiff Clays", Journal Geotech Engrg Div, Vol.105, No, 8, PP. 969-85, (1979).

20. Stevens, J. B., Audibert, J. M. E., "Re-examination of p-y Curve Formulation", Proceedings of the 11th Offshore Technology Conf, OTC, Houston , PP. 397-403, OTC 3402, (1980).

21. O’Neil, M. W., Gazioglu, S. M., "An Evaluation of p-y Relationships in Clays", Report Prepared for the American Petroleum Institute (API), University of Houston, Tex, (1984).