基于长期监测的高水压岩溶隧道二次衬砌水压特征研究

Study on Characteristics of Water Pressure on the Second Lining for High Water Level Karst Tunnel Based on Long Term Monitoring

通过长期监测宜万铁路4座典型高风险岩溶隧道运营期衬砌水压,结合模型试验、理论分析研究岩溶隧道二次衬砌水压的特征,提出岩溶隧道衬砌水压计算的概化模型。研究表明:(1)各隧道实测衬砌水压总体值不大,最大0.13 MPa,低于1 MPa抗水压衬砌设计值;断面水压分布受洞内排水效应影响明显;水压的动态与雨季关系密切。(2)岩溶隧道初始水压的确定主要受隧道上、下方的排泄基准面控制,施工过程中的泄水洞构成新的排泄基准面;初始水压与排泄能力和降雨的补给有关。(3)只有考虑隧道排水时才能发挥注浆加固圈对渗透水压的衰减作用;二衬水压受隧道排水量Q2与渗入初期支护的水量Q1的综合影响,二次衬砌上水压与Q2/Q1成反比。(4)排水洞排水通畅对二衬水压影响较大,在运营的过程中,应对排水洞进行定期的检查和维护,保证其排水通畅。本文可为高水压岩溶隧道的设计与运营提供参考。

In this paper, based on long term tunnel lining water pressure monitoring for 4 typical high-risk karst tunnels in Yi-Wan railway line, the character of water pressure on the second lining of the karst tunnels was studied, together with model test and theory analysis. A generalized model for karst tunnel was put up to esti- mate water pressure on the second lining. The study showed. （1）The overall level of the measured water pressure on the second lining of each tunnel was low with the maximum of 0.13 MPa, far below 1 MPa, the design value of water pressure resistant lining. The distribution of water pressure of the cross section was significantly affected by tunnel drainage, while water pressure dynamic was closely related with rainy season. （2）The determination of the original water pressure of karst tunnel was controlled by drainage base level on or under the tunnel. The original water pressure was also related with drainage capacity and rainfall replenishment. The release tunnel during construction formed the new drainage base level. （3）Only when there is drainage in tunnel, can the grouting reinforcement circle play the role of reducing water pressure on the lining. The water pressure on the second lining, inversely proportional to tunnel drainage（Qz） and water seepage into the primary lining （Q1）, was affected by Q2/Q1. （4）As the successful drainage of the release tunnel has great influence on the water pressure on the second lining, scheduled check and maintenance should be done during the operation of the release tunnel to ensure smooth drainage. The study can provide a reference for the design and operation of high water level karst tunnel.