Safety Analysis of Tunnel in Gob of High Steep Thick Coal Seam (I) - 2-D Numerical Simulation for Response

Abstract

Taking Wusongshan Tunnel in Tongling City as an example, two-dimensional numerical simulation of new large span highway tunnel directly through gob of steep coal seam were carried out to study the response of surrounding rock induced by mining. The actual location and scale of the ground fissure consistent well with the simulation results, which verified the analysis. The results showed that, different from those in gob of horizontal or gently inclined coal seam, the response of surrounding rock in gob of steep coal seam have the following characteristics: (1) shallow mining affects significantly on the values of settlement of earth surface and the tunnel, and deep mining on the scope; (2) in the shallow layer, a small scale coal being reserved or being effective filled after excavation can benefit greatly to the safety of structure and stability of the surrounding rock; (3) sharper uneven settlement would occour at the floor than the roof of coal seam, which can threaten the tunnel structure and should attract more special attention; (4) for this project, deep faults affect the safety of structure of tunnel and stability of surrounding rock also. Based on these results, treament plan were developed of Wusongshan Tunnel, which can also be refered for other similar projects.