隧道中不稳定块体的预测模型

In the tunnel construction, it is often encountered the engineering disaster that unstable blocks of instability across the fall, and the formation of unstable blocks of rock is mainly caused by the unfavorable combination of joints. Thus to predict the location of unstable blocks, the trajectory extending jointed surfaces need to first figure out. This paper analyzed the tunnel several major forms of joint surface, coming to the four kinds of common joint surface equation in the spatial coordinate system, by calculating the derivation, and by obtaining the joint surface equation, according to unfavorable joints combinations predicted the instability of the block exposed position, then put forward the concept of quasi-dangerous blocks, using the block limit equilibrium to analysis stress of quasi-dangerous blocks. Finally summed up in the roof and side walls easily block a potential swap joints and joint combination. From the view of engineering project, establishing a set of method for determining the unstable blocks, it has the instruction significance to the tunnel excavation.