基于拟静力法的地震作用下隧道掌子面动态稳定性上限分析

Upper Limit Analysis on Dynamic Stability of Tunnel Face Under Earthquake Force Based on Quasi-Static Method

地震是地下工程灾害的诱因之一,研究地震影响下隧道掌子面的稳定性具有重大意义。根据极限分析上限定理,运用Baker强度准则和拟静力法分别描述土体强度和地震力的影响,计算分析隧道掌子面的稳定性,并进行了对比分析和参数分析,研究结果表明:(1)计算结果与其他学者的研究结果接近,最大误差不超过6%,说明理论计算公式是合理且正确的,可以运用于实际工程当中;(2)随着影响剪切强度大小的参数A的增大,围岩压力非线性减小,当A<0.5时,围岩压力随着影响强度包络线曲率的参数n的增大而减小,当A>0.5时,围岩压力随着n的增大而增大;(3)围岩压力与控制强度包络线交点的参数T呈线性递减的关系,与水平、竖直地震加速度系数k_(h)、k_(v)均呈线性递增的关系;(4)当A、n或T减小时,隧道掌子面前方破坏范围增大,其中参数A效果最明显,n次之,T不太明显,当k_(h)、k_(v)增大时,隧道掌子面前方破坏范围也随之增大。

Earthquake is one of the causes of underground engineering disasters. It is of great significance to study the stability of tunnel face under earthquake force. According to the limit analysis, Baker strength criterion and quasi-static method were used to describe the influence of soil strength and seismic force respectively, and the tunnel face stability was calculated and analyzed. In addition, comparative analysis and parameter analysis were also carried out. The results are concluded as follows. Firstly, the calculation results are close to the research results of other scholars, and the maximum error does not exceed 6%. It shows that the theoretical calculation formula is reasonable and correct, which can be applied to practical engineering. Secondly, with the increase of the parameter A that affects the shear strength, the surrounding rock pressure decreases nonlinearly. When A is smaller than 0.5, the surrounding rock pressure decreases with the increase of the parameter n that affects the curvature of the strength envelope. When A is larger than 0.5, the surrounding rock pressure increases with the increase of n. Thirdly, the surrounding rock pressure has a linearly decreasing relationship with the parameter T of the intersection of the control strength envelope, and a linear increasing relationship with the horizontal and vertical seismic acceleration coefficients k_(h)and k_(v). Fourthly, as the decrease of A, n or T, the damage area in front of the tunnel face increases, and the parameter A has the most obvious effect, followed by n and T. With the increase of k_(h)and k_(v), the damage area in front of the tunnel face also increases.