下穿房柱式采空区隧道变形规律与控制研究

为了探究房柱式采空区开采过程和隧道下穿采空区施工过程的相互影响,以巴准铁路敖包沟隧道为依托,采用数值方法对施工过程中围岩变形与受力随施工步变化进行模拟分析。研究表明:隧道下穿房柱式采空区时,采空区开挖造成采煤柱压缩,采空区侧壁和煤柱发生较大水平位移,影响延伸至地表2倍采煤长度范围内;隧道下穿施工引起采空区底板与顶板竖向位移进一步增大,造成3倍开采深度范围内地表沉降;采空区、煤柱和地表变形随隧道开挖步变化规律相关性较高,且隧道拱顶受采空区底板变形的影响是引起失稳的主要原因。研究结果保障了敖包沟隧道下穿采空区的施工安全。

Study on Regularity and Control of Deformation of Tunnel Crossing Underneath Room-pillar Goaf

Ao’baogou tunnel crosses underneath the room pillar goaf of Zhongxing Coal Mine. In the paper, the construction of Ao’baogou tunnel crossing underneath the room pillar goaf and the regularity of the construction mechanics and the deformation of the surrounding rocks during different tunnel excavation steps are simulated and analyzed by means of MIDAS GTS. Conclusions drawn are as follows: 1) When the tunnel crosses underneath the room pillar goaf, the excavation of the room pillar goaf leads to the compression of the coal pillars and the significant horizontal displacement of the side walls and the coal pillars, and the influence extends the scope of 2 times the coal excavation length on the ground surface; 2) The construction of the tunnel crossing underneath the room pillar goaf increases the vertical displacement of the floor and roof of the goaf, which results in ground surface settlement within the scope of 3 times the excavation depth; 3) The deformation of the goaf, the coal pillars and the ground surface is closely correlated with the tunnel excavation steps, and the influence on the tunnel crown imposed by the deformation of the floor of the room pillar goaf is the main cause for the tunnel collapse. The study results have been applied in the construction of Ao’baogou tunnel, which guarantees the safety of tunneling underneath the room pillar goaf.