Effects of liquefaction-induced large lateral ground deformation on pile foundations

WANG Yan-li(王艳丽)^{1, 2}, CHENG Zhan-lin(程展林)¹, WANG Yong(王勇)²

(1. Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources
(Yangtze River Scientific Research Institute), Wuhan 430010, China;
2. State Key Laboratory of Geomechanics and Geotechnical Engineering (Institute of Rock and Soil Mechanics, Chinese Academy of Sciences), Wuhan 430071, China)

Abstract:The pile-soil system interaction computational model in liquefaction-induced lateral spreading ground was established by the finite difference numerical method. Considering an elastic-plastic subgrade reaction method, numerical methods involving finite difference approach of pile in liquefaction-induced lateral spreading ground were derived and implemented into a finite difference program. Based on the monotonic loading tests on saturated sand after liquefaction, the liquefaction lateral deformation of the site where group piles are located was predicted. The effects of lateral ground deformation after liquefaction on a group of pile foundations were studied using the finite difference program mentioned above, and the failure mechanism of group piles in liquefaction-induced lateral spreading ground was obtained. The applicability of the program was preliminarily verified. The results show that the bending moments at the interfaces between liquefied and non-liquefied soil layers are larger than those at the pile’s top when the pile’s top is embedded. The value of the additional static bending moment is larger than the peak dynamic bending moment during the earthquake, so in the pile foundation design, more than the superstructure’s dynamics should be considered and the effect of lateral ground deformation on pile foundations cannot be neglected.

Key words:liquefaction-induced lateral spreading ground; pile foundation; large post-liquefaction deformation; finite difference method