岩溶地区地下水位变动带隧道涌水问题的思考

通过鸡冠山隧道涌水实例及广泛收集岩溶地区隧道涌水案例，总结出岩溶地区隧道季节变动带涌水具有反应时间快、水量大、泥沙重的特点，并综合分析地下水季节变动带隧道的水文地质特征，将其划分为一般山岭隧道及向斜构造地下水位变动带两种类型，且对两种类型涌水机理进行了阐述。岩溶地区隧道前期勘察应重点划分隧道岩溶地下水系统及地下水动力分带，查明岩溶发育特征与规律；施工期和运行期应结合岩溶揭露情况和涌水情况开展针对性的补充勘察，做好降雨、涌水过程和涌水压力监测，判断和预测最大外水压力和涌水量。针对涌水问题，提出封堵和排泄两种处理思路:施工开挖揭露的岩溶现象不可盲目封堵，需尽可能维持原通道的通畅，针对可能涌水的隧道衬砌设计不可仅考虑围岩结构，应充分考虑外水压力，做好围岩固结灌浆；常规隧道“环形排水系统+中心沟”排水系统可靠性差，针对大流量涌水，多采用泄水洞排水。 

Thoughts on tunnel water inrush in changing zones of groundwater level in karst areas

Based on analyses of the water inrush cases in the Jiguanshan tunnel and other examples in karst areas, it is summarized that water inrush in seasonal variation zones of tunnels can be characterized by fast response, large water volume and heavy sediment load. Based on hydrogeological features of tunnels in seasonal variation zones of groundwater, they are divided into two types， general mountain tunnels and tunnels associated with synclinal structural groundwater level variation zones. The mechanisms of water inrush are presented for both types. During the preliminary investigation of tunneling in karst areas, the demarcation of karst groundwater systems and groundwater dynamic zones should be focused on to understand the characteristics of karst development. During construction and operation periods, supplementary investigation should be carried out in combination with karst exposure and water inrush, which includes rainfall monitoring, water inrush and pressure monitoring to predict the maximum water pressure and inflow. Regarding water inrush, two treatment methods, i.e. dredging and blocking, are proposed and explained. The karst caves exposed during construction should not be simply blocked and the original passage should be well maintained. The lining design of the tunnel with possible water inrush should not only consider the surrounding rock structure, but also the external water pressure. Consolidation grouting should be applied where necessary. Due to the poor reliability of the regular annular drainage system and central ditch , in case of the large inflow of water, drainage tunnel should be used to drain water.