Seismic Performance Analysis Of Bridge Group Pile Foundation

Group pile foundation is always introduced in bridge engineering by right of its advantages such as great load capacity,little sinkage,good stability, besides it has much better seismic capacity than other kind foundation. But it is still the vulnerable component from the result of earthquake damage investigation. Further research to its seismic performance is immediately needed. The paper adopts Nonlinear Pushover Analysis Method to study seismic performance influence factor of bridge group pile foundation and improvement, based on nonlinear analysed model. The main content is as follows:(1) At first analysis method of studying group pile foundation seismic performance is presented, including Pushover Analysis Method,simulation of nonlinear analysis model,seismic performance guide line definition of group pile .And imulation of pile group material,pile element,pile-soil interaction is involved in the second part.(2) Nonlinear analysed model is validated and parameter analysis is done. It is indicated that the adopted Nonlinear Fiber Beam-Column Element and p-y curve method are reasonable and correct. Considering group pile effect or not and ratio of pile space to pile diameter can infect group pile foundation seismic performance greatly through analysis. Considering group pile effect is necessary during reality analysis. Soil parameter analysis is also studied, clay soil includes undrained shear strength and the effective unit weight of soil the two parameters, sand includes effective friction angle of sand and the effective unit weight of sand the two parameters, it is found that these soil parameters have infection to group pile foundation seismic performance.(3)It develops two classical pile group foundation models, considering clay soil and sand soil these two kind groundsills. Based on the two models, the paper study group pile foundation seismic performance infection rule of bottom pile cap loading state. It shows that, bottom pile cap loading state has a great sensitivity to part of group pile foundation seismic performance. In addition, study of scouring effect influencing group pile foundation seismic performance is done in paper,and get some significance result.(4) Based on former part study, it is tried to discussed some promotions which can improve group pile foundation seismic performance, including seting inclined pile,increasing pile reinforcement rate and seting coupling bar between piles these three manner. It is showed that pile group foundation seismic performance can be promoted by these three methods to a certain exrent.