隧洞开挖过程中地应力耦合动态卸荷效应分析

Effect of Dynamic Unloading Coupled with Geo-stress during Tunnel Excavation

通过理论计算和现场实测资料对比验证相结合的方法研究了圆形隧洞在开挖过程中开挖边界上径向、剪切地应力及二者耦合的动态卸荷效应。计算结果表明:隧洞在开挖过程中,径向应力卸荷时程曲线大于剪切应力卸荷时程曲线;在最大主应力方向,径向、剪切地应力耦合的卸荷应力时程曲线是二者之和,而在最小主应力方向,二者耦合的卸荷应力时程曲线则为二者之差;最后,通过与工程实例的结合,说明在最大主地应力方向,围岩水平径向振动是由于径向、剪切应力的耦合卸荷诱发的。

The dynamic effect of circular tunnel induced by unloading of radial in-situ stress, shearing in-situ stress and the coupled result during blasting was studied by theoretical calculation and monitored data. Results show that during excavation, the unloading curve induced by radial in-situ stress is larger than that induced by shearing in-situ stress. In the maximum principal geostress direction, the unloading curve induced by coupled effect is the summation of radial in-situ stress and shearing in-situ stress. While, in the minor principal geostress direction, the unloading curve induced by coupled effect is equal to the difference of radial in-situ sti＇ess and shearing in-situ stress. Combined with a project example, in the maximum principal geostress direction, the horizontal vibration was induced by coupled dynamic unloading of radial in-situ stress and shearing in-situ stress.