Research On Efficacy Of Rigid-Drainage Pile Improvement On Liquefiable Sloping Ground By Shaking Table Tests

Lateral deformation often occurs in liquefiable sloping ground during earthquake,which causes severe damage to the nearby constructions and foundation projects.In recent years,the study of lateral deformation caused by liquefaction of inclined foundation has become one of the hot topics in the field of geotechnical seismic engineering.Domestic and foreign scholars have done a lot of research on the pile-soil interaction in the liquefiable sloping ground,and have been seeking effective measures to limit the lateral deformation caused by sand liquefaction.Installing piles into sloping ground has been proven to be effective in reducing the lateral deformation.Rigid-drainage pile is an effective anti-liquefaction treatment measure for foundation which combines the bearing capacity of rigid pile and the drain-ability of gravel pile,and its anti-liquefaction performance has been fully verified in horizontal liquefiable ground,and further research is needed on anti-liquefaction effect in inclined liquefiable ground.Based on these,in this paper,the liquefaction resistance of the rigid-drainage piles in the liquefiable inclined field is studied by the shaking table test and the numerical simulation method,especially the effect of limiting the lateral deformation of the liquefied sand,and the mitigation efficiencies of rigid-drainage piles and ordinary rigid piles are compared.This can provide a new possibility for the treatment of liquefiable sloping grounds.At the same time,it also has certain reference significance for the application and promotion of rigid-drainage pile in the future.The main research contents and results of this paper are as follows:(1)Based on the shaking table test,a comparative study was carried out between the rigid-drainage piles and the ordinary rigid piles in the liquefiable sloping ground,and the development law of the eccess pore water pressure at different buried depths of the groung and the flow property of the surface liquefied soil was obtained.The test results show that the rigid-drainage piles can effectively limit the lateral deformation caused by liquefaction,and are an effective treatment measure for strengthening the liquefiable sloping ground.(2)In the shaking table test,by changing the arrangement form of group piles,the influence of the triangular arrangement and the square arrangement of the rigid-drainage piles on the effect of treating the liquefiable sloping ground was studied.The test results show that the triangular arrangement form of group piles is more effective in restricting the lateral deformation than the square arrangement form of group piles,and is beneficial to the anti-liquefaction performance of the rigid-drainage piles.(3)Based on the FLAC3 D finite difference software,the numerical models of the rigid-drainage piles and the ordinary rigid piles in the liquefiable sloping ground were established respectively to study the effect of the rigid-drainage piles in in reinforcement of liquefiable sloping ground and further reveal the flow characteristics of the internal liquefied sand.Then,the numerical results are compared with the experimental results,and the two results are basically consistent in the main laws.(4)In order to study the effect of pile spacing,slope angle and dynamic acceleration peak on the liquefiable sloping ground treated by rigid-drainage piles,the corresponding numerical models were established by FLAC3 D software.Through the numerical analysis,some laws under the influence of different parameters are obtained,including the variation law of the excess pore pressure ratio,the lateral displacement law of the liquefied sand and the horizontal displacement law of the center pile top.