复杂地质病害隧道衬砌拆除塌方机理及处治措施

为研究病害整治隧道二衬拆除塌方机理及处治措施,以重庆某隧道二衬拆除过程中拱顶塌方为例,分析塌方段地质条件、病害状况及塌方过程等,探究塌方发生机理及其处治措施。结果表明:隧道衬砌腐蚀、开裂、渗漏水等病害以及塌方段围岩松散破碎,具有腐蚀性的地下水使得围岩呈现“结构性弱化”,是产生塌方的主要内因;施工扰动下,块碎石堆积荷载超过初支的极限承载力,导致初支开裂,暴雨天气又使得上覆岩层重量增加是导致塌方的主要外因。采用分台阶开挖塌方体,空腔处泵送砼回填,配合使用超前小导管、锁脚锚杆、钢拱架等支护措施,清除塌方堆积体并重新浇筑衬砌结构,可为类似工程塌方处理提供借鉴。

Collapse Mechanism of Lining Removal and Treatment Measures in Diseased Tunnel with Complex Geology

To study the collapse mechanism and treatment measures of lining removal in diseased tunnel, a tunnel collapse in Chongqing was taken as an example to record the collapse process. By analysing to the geological conditions, tunnel disease conditions and process of collapse, the mechanism of collapse and its treatment measures were explored. The results show that corrosion, cracking, leakage and other diseases of tunnel lining concrete, loose and broken surrounding rock in the tunnel collapse section and the "structurally weakened" surrounding rock by corrosive groundwater are the main internal cause of tunnel collapse. Under the construction disturbance, the accumulation gravity of crushed stone exceeds the ultimate bearing capacity of the primary support, leading to the cracking of the primary support, and the heavy rain makes the weight of the overlying strata increase, which is the direct cause of the collapse. The way of step excavation is adopted in the process of collapse treatment, the cavity is backfilled by pumping concrete, and the supporting measures such as advanced small pipe, feet-lock bolt and steel arch are used to remove the collapse accumulation and re-cast the lining structure. That can provide reference for similar collapse treatment.