A unified equation of failure envelope for skirted foundations in normally consolidated clay
FAN Qing-lai1, 2, LUAN Mao-tian2, GONG Xiu-bin1
(1. Key Laboratory of Geotechnical Engineering, Ludong University, Yantai 264025, China; 2. State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China)
Abstract:The shape of failure envelope for skirted foundations under combined loading is complex and strongly dependent on embedment ratio when the traditional load reference point, i.e., the base center, is utilized. To overcome the difficulty to obtain a closed-form equation to describe the shapes of failure envelopes for skirted foundations with a range of embedment ratios, an efficient searching procedure for the optimal load reference point is suggested and implemented in the finite element package ABAQUS. Using the optimal load reference point, the failure envelope obtained through combining swipe loading and fixed displacement ratio probing can be approximated as an ellipse in normalized moment-horizontal load space. Then a unified double parameter equation is proposed, which can be utilized to estimate the combined capacity of skirted foundations in normally consolidated clay within practically acceptable accuracy. The values of the two parameters are also presented for a range of practical embedment ratios. The rationality of the proposed equation is validated by comparing the present solutions with the experimental data from a given centrifuge model test.
作者简介: Biography: FAN Qing-lai (1977– ), Male, Ph.D., Associate Professor. He has been engaged in studies on the basic theory and numerical analysis of soil and marine soil mechanics.
引用本文:
范庆来, 栾茂田,宫秀滨. 正常固结软黏土地基上裙板式基础统一破坏包络面方程[J]. 岩土工程学报, 2012, 34(10): 1917-1924.
FAN Qing-lai, LUAN Mao-tian, GONG Xiu-bin. A unified equation of failure envelope for skirted foundations in normally consolidated clay. Chinese J. Geot. Eng., 2012, 34(10): 1917-1924.
[1] ANDERSEN K H, MURFF J D, RANDOLPH M F. Suction anchors for deepwater applications[C]// Proceedings of the First International Symposium on Frontiers in Offshore Geotechnics. London: Taylor and Francis, 2005: 3–30. [2] CHEN Yu-min, LIU Han-long, CHEN Ze. Working mechanism and numerical simulation of assembly coastal building techniques[J]. Journal of Central South University of Technology, 2008, 15(S2): 180–185. [3] BRANSBY M F, RANDOLPH M F. The effect of embedment depth on the undrained response of skirted foundations to combined loading[J]. Soils and Foundations, 1999, 39(4): 19–33. [4] BRANSBY M F, RANDOLPH M F. Combined loading of skirted foundations[J]. Géotechnique, 1998, 48(5): 637–655. [5] YUN G, BRANSBY M F. The horizontal-moment capacity of embedded foundations in undrained soil[J]. Canadian Geotechnical Journal, 2007, 44(5): 409–424. [6] GOURVENEC S. Effect of embedment on the undrained capacity of shallow foundations under general loading[J]. Géotechnique, 2008, 58(3): 177–185. [7] BRANSBY M F, YUN G. The undrained capacity of skirted strip foundations under combined loading[J]. Géotechnique, 2009, 59(2): 115–125. [8] BYRNE B W, CASSIDY M J. Investigating the response of offshore foundations in soft clay soils[C]// Proceedings of the 21st International Conference on Offshore Mechanics and Arctic Engineering, Oslo, Norway, 2002: 534–538. [9] MARTIN C M, HOULSBY G T. Combined loading of spudcan foundations on clay: numerical modeling[J]. Géotechnique, 2001, 51(8): 687–699. [10] FAN Qing-lai, LUAN Mao-tian, MENG Xiang-bo. A modified limit equilibrium analysis method for determining pull-out resistance of suction caissons located in soft ground[J]. Journal of China University of Mining & Technology, 2009, 38(3): 346–350. (in Chinese) [11] BRANSBY M F, RANDOLPH M F. The effect of skirted foundation shape on response to combined V-M-H loadings[J]. International Journal of Offshore and Polar Engineering, 1999, 9(3): 214–218. [12] TAN F S. Centrifuge and theoretical modeling of conical footings on sand[D]. Cambridge: University of Cambridge, 1990. [13] GOURVENEC S, RANDOLPH M F. Effect of strength non-homogeneity on the shape of failure envelopes for combined loading of strip and circular foundations on clay[J]. Géotechnique, 2003, 53(6): 575–586. [14] BRANSBY M F, RANDOLPH M F. Shallow foundations subjected to combined loadings[C]// Proceedings of the 9th International Conference on Computer Methods and Advances in Geomechanics, Wuhan, China, 1997: 2–7. [15] FAN Qing-lai, LUAN Mao-tian. Bearing capacity of shallow foundations subjected to horizontal and moment loading[J]. Journal of Hydraulic Engineering, 2010, 41(10): 1201–1207. (in Chinese) [16] YUN G. Centrifuge and numerical modelling of skirted foundations subjected to combined loads[D]. Dundee: University of Dundee, 2006.