地震时隧道衬砌受力敏感性的简化理论分析

Simple Theorctical Analysis on Sensitivity of Tunnel Lining Internal Forces Due to Earthquake Action

摘要:

为了分析地震区隧道对各影响因素的敏感性,把隧道简化为圆形用拟静力法考虑地震的作用;围岩压力简化为均布,运用结构力学中的力法原理,结合敏感度函数的定义,推导了衬砌的内力(弯矩、轴力、剪力)关于垂直和水平地震作用力、地震作用下增加的孔隙水压力和围岩压力的敏感度函数。并对一工程实例进行了计算。结果表明:衬砌内力对各影响因素的敏感性与各因素数值的大小无关,与衬砌结构形状及侧压力系数有关;并随着侧压力系数的增加敏感性减小,表明浅埋隧道对地震的作用更敏感;衬砌对水平地震作用敏感性最大,并指出了一些最敏感的部位;孔隙水压力的存在有助于改善隧道的受力。

Abstract:

A pseudo-static analysis method is presented to calculate sensitivity of lining internal forces due to earthquake action considering influential factors such as vertical and horizontal seismic loads, pore pressure build up, and rock pressure. The method is applied to a engineering project also. Results show that： the sensitivity has no relation to the value of the influential factors, but to the shape of the tunnel and coefficient of lateral pressure; the sensitivity is in the direct proportion to the coefficient of lateral pressure, which implies that shallow buried tunnels are more sensitive to seismic load; horizontal seismic load is the most sensitive factor of lining forces and some most sensitive positions are given; water pore pressure is good to lining＇s internal forces.