Improvement of design method of rock-socketed pile based on the enhancement effect of shaft resistance
Abstract
Large diameter rock-socketed piles are usually used to support bridge with long-span or high piers. To research its mechanical properties in mountain area, field loading tests based on distributed fiber sensing technique were performed. The tests results indicate that shaft resistance came into play earlier than tip resistance and the upper load was borne mainly by shaft resistance. When the load-sharing ratio of tip resistance exceeded 10%, the enhancement phenomenon of shaft resistance occurred, which became more and more obvious with the increase of the ratio. The shaft resistance and tip resistance are not independent but interact of each other. The increase of tip resistance can promote the shaft resistance to play its role effectively. According to the field test results, the design method of rock-socketed piles was improved based on the enhancement phenomenon of shaft resistance. The calculation results indicate that the rock-socketed length of pile can be shorten effectively by this method which can obtain considerable economic benefits.
References
Pells, P.J.N., Turner, R.M. 1979. Elastic solutions for the design and analysis of rock-socketed piles. Canadian Geotechnical Journal 16: 481-487.
Williams, A.F., Johnston, I.W., Donald, I.B. 1980. The design of socketed piles in weak rock. Golden Jubilee of the International Society for Soil Mechanics & Foundation Engineering Commemorative Volume 1.
Rowe, R.K.; Armitage, H.H. 1987. A design method for drilled piers in soft rock. Canadian Geotechnical Journal 24: 126-142.
Seidel, J.P., Collingwood, B. 2001. A new socket roughness factor for prediction of rock socket shaft resistance. Canadian Geotechnical Journal 38: 138-153.
Turner, J. 2006. Rock-socketed shafts for highway structure foundations: a synthesis of highway practice. NCHRP Synthesis 360. National Cooperative Highway Research Program (NCHRP), Transportation Research Board, Washington, D.C.
Hooley, P, Lefroy, S.R. 1993. The ultimate shaft frictional resistance mobilised by bored piles in over-consolidated clays and socketed into weak and weathered rock. In: Cripps JC et al., editors. The engineering geology of weak rock. Rotterdam: Balkema; p. 447-455.
Kulhawy, F.H, Phoon, K.K. 1993. Drilled shaft side resistance in clay soil to rock. Proceedings of the Conference on Design and Performance of Deep Foundations: Piles and Piers in Soil and Soft Rock. Geotechnical Special Publication No. 38, Reston, VA: ASCE, p. 172–183.
Carrubba, P. 1997. Skin friction on large-diameter piles socketed into rock. Canadian Geotechnical Journal. 34(2): 230-240.
Rosenberg, P., Journeaux, N. 1976. Friction and end bearing tests on bedrock for high capacity socket design. Canadian Geotechnical Journal. 13(3): 324–333.
Horvath, R.G., Kenney, T.C., Kozicki, P. 1983. Methods of improving the performance of drilled piers in weak rock. Canadian Geotechnical Journal 20: 758-772.
Rowe, R. K., Armitage, H. H. 1987. A design method for drilled piers in soft rock. Canadian Geotechnical Journal 24: 126-142.
Zhang, L., Einstein, H. H. 1999. End bearing capacity of drilled shafts in rock. Journal of Geotechnical and Geoenvironmental Engineering. 124(7): 574–584.
Charles W. W. Ng, Terence L. Y. Yau, Jonathan H. M. Li, and Wilson H. Tang. 2001. Side resistance of large diameter bored piles socketed into decomposed rocks. Journal of Geotechnical and Geoenvironmental Engineering. 127(8): 642-657.
Zhang, L., and Xu, J. 2009. Axial load transfer behavior of rock socketed shafts. In Contemporary Topics in Deep Foundations, Selected Papers from the 2009 International Foundation Congress and Equipment Expo, Orlando, Fla., 15-19 March 2009. Geotechnical Special Publication No.185. Edited by M. Iskander, D.F. Laefer, and M.H. Hussein. American Society for Civil Engineers, Reston, Va. pp.175-182.
Rowe, R.K., Armitage, H.H. 1987. Theoretical solutions for axial deformation of drilled shafts in rock. Canadian Geotechnical Journal 24: 114-125.
Zhang, L., and Einstein, H. H. 1998. End bearing capacity of drilled shafts in rock. Journal of Geotechnical and Geoenvironmental Engineering. 124(7): 574–584.
Vipulanandan, C., Hussain, A., Usluogulari, O. 2007. Parametric study of open core-hole on the behavior of drilled shafts socketed in soft rock. Geotechnical Special Publication 1-10.
Zhang, L.Z. 2008. Prediction of end-bearing capacity of rock-socketed shafts considering. Canadian Geotechnical Journal 47: 1071-1084.
