下伏水平采空区隧道开挖稳定性数值模拟

Numerical simulation of stability in excavation of tunnel over underlain horizontal goaf

采空区的存在将对隧道开挖过程中洞周位移和支护内力产生不利影响。本文以观斗山隧道为依托工程,采用有限元软件FLAC^(3D)模拟了下伏水平采空区隧道的开挖过程,分析了采空区与隧道不同间距对隧道洞周位移和支护内力的影响。结果表明:当两者的间距<12 m(1倍洞径)时,随着下伏采空区与隧道间距增大,采空区对隧道的不利影响显著减小;当间距由12 m增加至24 m时,这种影响逐渐减弱并趋于稳定;下伏水平采空区对隧道施工安全性影响的临界距离可定为2倍隧道洞径。

The existence of goaf has negative effects on peripheral displacement of tunnel and internal force of support during excavation. Based on Guandoushan tunnel,FLAC^（3D） was used to simulate the excavation process of tunnel over underlain horizontal goaf. The effects of different distance between tunnel and goaf on peripheral displacement of tunnel and internal force of support were analyzed. The results show that the negative effects decrease obviously with the distance increase to 12 meters（ 1 times the tunnel diameter）. How ever,the negative effects decrease gradually and tend to be stable when the distance increase from 12 meters to 24 meters,namely the critical distance of the construction safety is 2 times the tunnel diameter.