铁路桥梁桩基础抗震性能拟静力试验研究

Study on the Static Test of Anti-earthquake Performance of Railway Bridge Pile Foundation

为了研究群桩基础在水平荷载作用下地基土及桩身进入非线性状态后桩身内力变化过程和应力分布规律，通过对群桩基础缩尺比例模型进行拟静力试验，分析研究桩基础的破坏机制、承载能力及桩身应力分布;采用M塑性铰模拟墩的弹塑性、PMM塑性铰模拟变轴力作用下桩身的弹塑性和日本规范中推荐的方法模拟土的非线性建立有限元模型，对群桩-承台-墩整体结构进行PUSHOVER分析。结果表明：（1）水平荷载作用下，各桩受力不均匀，外排桩的桩身应力大于内排桩的桩身应力;（2）高承台桩桩身最大应力点位于土面以下2-4倍桩径范围内。

In order to study the change process of internal forces and distribution rule of stress of pile considering nonlinear behaviors of pile shaft and subsoil under lateral loads, the pseudo-static test on scale model are carried out to study failure mechanism, bearing capacity and stress distribution of pile. A nonlinear static calculation model of pile group foundations is put forward to conduct Pushover analysis on pile-pile cap-pier structure, in which the elastoplastieity of pier shafts is simulated by M plastic hinge, pile shafts in variable axial loads issimulated by distributed PMM plastic hinge and nonlinearity of subsoil is simulated by the method given in Japan Railway Code. The results show that ： （ 1 ） Under lateral loads, piles are not loaded uniformly, and the stress of outer row of pile is greater than the inside row of pile. （2） The maximum stress point of tall platform pileis located at the depth of about 2 -4 radius.