桩-土水平弹簧系数对桥梁地震反应影响的参数分析

Parameter analysis on the influence of soil-pile horizontal spring coefficient on the seismic response of bridges

集中参数法是目前土木工程抗震计算中考虑桩土地震相互作用的实用方法。从有限元方法的角度来看,集中参数方法将地层半无限空间模型化为一个无几何尺度的抽象的力学单元,这里称其为宏单元,其计算模型的选用和参数确定直接影响计算结果的精度。针对不同的地震动输入和工程中各种常见的土层,基于考虑土体非线性的Boulanger宏单元,m法和Mindlin解等三种桩—土水平弹簧模型,进行了详尽的参数分析工作,旨在说明对桥梁地震反应影响很大的桩-土水平弹簧系数的取值问题。

The concentration parameter method is a major solution in the seismic analysis and design of bridges. From the view angle of finite element,in the concentration parameter method,the stratum semi-infinite space was considered as an abstract mechanical element without geometric dimensions,which is called macro- element. The determination of the model parameters , such as the interaction spring stiffness, the damping and the equivalent mass for the soil around the piles is crucial to the calculation precision. Taking into account common types of soil in engineering and different input of seismic waves , a comparative study was made among the Boulanger model , the ‘ m ’ method and the Mindlin method （which is equivalent to a linear spring model） based on a large number of parameter analyses, aiming at explaining the key point of the selection of horizontal soil-pile spring coefficient which has a strong influence on the seismic response of bridges.