整体式桥台地震反应机理分析

整体式桥是一种新的桥型，能够极大地节省长期维护和运营费用，值得在国内大力推广应用，但目前对整体式桥台在地震作用下的动力反应还很缺乏认识。通过对典型的单跨整体式桥台的地震反应进行动力数值模拟，分析了地震加速度峰值、桥台高度、桥梁跨度等主要因素的影响及其机理，并探讨了桥台后增加柔性隔离层及采用加筋土这两种措施的减震效果。结果表明，目前桥台抗震规范采用的M-O方法不能合理地描述整体式桥台后动土压力的大小和分布，其预测结果偏不安全；柔性隔离层虽然可以减小桥台后的动土压力，但同时也会导致较大的桥台变形和弯矩；填土中加筋能够提供水平拉力，可以有效减小地震作用下桥台的最大弯矩和水平位移。

Analysis of seismic response of integral bridge abutments

As a new bridge type, integral bridge can significantly reduce the long term maintenance cost, and its application should be encouraged in China. However, there is great uncertainty about the dynamic performance of integral abutments during earthquake. This paper presents the findings from a dynamic numerical simulation about a typical integral bridge. The influence of seismic peak acceleration, abutment height, and bridge deck length has been investigated. The effects of two mitigation methods, e.g. installation of a flexible layer and reinforced soil behind the abutment, have also been discussed. The results show that the traditional M-O method adopted in the current bridge abutment design code cannot give a reasonable prediction about the dynamic earth pressure behind integral abutment, which would lead to an unsafe design. Although a flexible layer can reduce the earth pressure, the deformation and bending moments will increase. Reinforcement can provide horizontal tensile forces to the abutment, leading to reduce abutment deformation and bending moments.