大跨度特长隧道穿越煤系地层的防侵陷处治研究

Treatment Study of Depression Through the Coal Strata in Large Span Long Tunnel

煤系地层软弱破碎带是隧道开挖支护施工中风险较多、容易出现事故的地段之一。结合湖北省保宜高速公路红岩寺隧道的实例,该隧道穿越软弱破碎煤系地层,属典型煤系地层隧道;鉴于煤系地层围岩软弱破碎的严重程度,为安全起见,用精度较高、距离较短的地质雷达对揭露煤层进行了超前预报。首先对其施工过程中面临的各种风险进行了综合分析,包括揭煤施工风险、瓦斯突出风险、采空区施工风险、围岩大变形风险以及塌方风险等。进而有针对性地对围岩大变形提出了风险规避措施,包括安全管理与地质超前预报、设计初期支护参数、超前小导管注浆加固、调整施工工法和安全步距、排水措施及现场监控量测等。同时,对施工中收敛变形、拱顶下沉等测量数据进行了曲线分析,动态反馈于施工过程中。该方法在隧道穿越煤层软弱破碎带施工指导中取得了令人满意的结果。

The fault and crush zone through coal strata is very dangerous and catastrophic sector of the tunnel during the course of excavation and support. As a typical coal formation tunnel,Hongyansi Tunnel would traverse the soft and weak coal formation surrounding rock. Given the weak and crushing severity of surrounding rock,the highly accurate and short-distance geology prediction were conducted with geological radar. Firstly,the risks in the tunnel construction progress are analyzed,including seam opening construction risk,gas ejection risk,construction risk in mined-out area,large deformation risk of surrounding rock,collapse risk,and the side,etc. And then,some relevant risk averse methods about surrounding rock deformation are presented,such as closing working face as soon as possible,safety management and geological advance prediction,parameter design of preliminary support,advanced small pipe grouting,adjusting the construction technology and safety distance,drainage and site monitoring,etc. At the same time,the analysis results of measured data such as convergence and subsidence of crown are dynamically fed back to the construction. These processes are called the information construction of the tunnel in a fault and crush zone,which is applied to the tunneling through coal strata and gives a satisfying effect.