高地应力条件下隧洞开挖动态卸荷的破坏机理初探

A primary study to damage mechanism of initial stress dynamic unloading when excavating under high geostress condition

分析了高地应力条件下静水压力场中圆形隧洞钻爆开挖时开挖边界上初始应力场动态卸荷效应及破坏机理,并计算了其破坏范围。初始应力动态卸荷时,动应力在隧洞径向表现为卸荷回弹,而在切向出现动应力集中,表现为加载。动态卸荷时间对径向应力的影响较对切向应力大,卸荷时间越短,扰动的幅度越大;初始应力动态卸荷在岩体中所造成的破坏范围较准静态卸荷情况大,卸荷时间越短,破坏范围越大。

The dynamic unloading effect of initial stress in hydrostatic field in excavation process of circlar tunnel by blasting under high geostress condition was studied and the damage field was caculated. In the process of dynamic unloading, the radial stress unloaded first and then rebounded, the circumstress concentrated. The unloading time affects the radial stress much more than the circum-stress. The shorter the unloading time is, the larger the influenced field is. The damage field induced by dynamic unloading is larger than that induced by static unloading.