地下洞室开挖对断层滑动影响的理论分析

Theoretical Analysis on the Influence of Understructure Excavation on Fault Slipping

为研究地下洞室的开挖对既有断层滑动的影响,基于均匀介质弹性理论,利用无限大介质中集中力作用下的解析解,探讨了断层倾角、水平构造应力对断层的应力分布以及滑动的影响。研究结果表明:断层倾角对断层法向应力影响较大,法向应力的最大值出现在距开挖点最近处,断层倾角增大,法向应力变小,切向应力的绝对值也变小,剪应力最大值则出现在α=±π/6附近。水平构造应力系数对断层的法向应力、切向应力的分布影响不大,随着水平构造应力系数的增加,峰值法向应力略有增加,而切向应力则略有下降。对于断层滑动,断层倾角影响较为显著:随着断层倾角的增大,断层出现了大范围滑动;水平构造应力系数的增加,使得断层带的滑动范围变小,较高的水平构造应力更有利于保持断层带的稳定。

In order to research the influence of understructure excavation on the fault slipping, based on theelasticity theory of homogeneous media, with the analytical solution of central load acts on the infinite medium,the paper discusses the influence of fault dip angle and horizontal stress on the stress distributing and slippingcondition of fault. The research shows that fault dip angle has a larger impact on the normal stress than on theshear stress, the biggest normal stress emerges on the place that is nearest to the centre of excavation; with thedip angle increasing, the normal stress decreasing; the biggest shear stress emerges on the site of α=±π/6.The coefficient of horizontal stress is of little impact on both normal stress and shear stress; with the coefficientof horizontal stress increasing, the normal stress slightly increasing, while shear stress slightly decreasing. Thedip angle is of a great impact on the slipping condition of fault; with the dip angle increasing, the bigger scope offault becomes slipping; and with the coefficient of horizontal stress increasing, the slip scope of fault becomessmaller. The higher coefficient of horizontal stress favors the stability of fault.