Research On Bearing Stratum Under Pile Toe In Loess Regions Under Seismic Wave

Loess distributes in the Central and Western Regions of arid and semiarid in our country, in these regions earthquake is very common and the seismic intensity is high. So the study of loess dynamics is very important, a lot research work do on loess site dynamics in recent years, but little on bearing stratum under pile toe. As Development of the West Regions, pile foundation becomes one of the most important foundation forms in loess regions, seismic wave spreads from bedrock to bearing stratum, then to pile foundation, so the stability of pile sharp reacts to the bearing stratum dynamics, especially to end bearing pile and friction column pile, the bearing stratum dynamics concern to bearing capacity and security of pile. So we must discuss the bearing stratum dynamics, to prevent bearing stratum ineffective caused by seismic force.This paper use ANSYS modeled pile-foundation soil by three-dimensional dynamic simulation, in the model, foundation use DP model, use correct VonMisis yield criterion, and between the pile and foundation soil use surface-surface contact cell, boundary condition use Lysmer's ciscid boundary, when bring to earthquake bear we use large mass method, model the reaction between pile and foundation soil reasonable, analyze there are weak underlying stratum under bearing stratum, through the compare of stress and strain between bearing stratum soil and underlying stratum soil, we can get the stress and strain of weak underlying stratum diffuse quickly, and it will affect sedimentation of pile.And this paper modeled and analyzes simplex pile when it empty in pile toe and when it gated mortar in pile toe, when it empty, the bearing capacity of pile develop on friction resistance of pile side face, the stress of pile toe is very small, not do it work almost, when it gated mortar in pile toe, except the friction resistance of pile side face work full, the stress of soil which gated mortar in pile toe is increase, it means the friction resistance of pile toe is increase, and in these two different situations, the pile dynamics under seismic force is different. The displacement of pile when it empty in pile toe is larger than it when pile gated mortar in pile toe marked. From the above we can see, it can improve and ensure the stability of pile marked when the pile gated mortar in pile toe.