长坪隧道浅埋软弱围岩段施工监测与结构承载状况分析

Construction monitoring and analysis of structure bearing capacity for Chang-Ping tunne located in shallow-buried and weak surrounding rock area

通过对长坪隧道出口浅埋软弱围岩段施工的跟踪监测,分析和总结了围岩变形、锚杆轴力、围岩压力、钢拱架内力、喷射砼与二次衬砌砼结构的承载状况,研究结果表明:该洞段采用台阶分部开挖法施工是适宜的,它能较为有效地抑制围岩的变形;隧道拱部施筑的锚杆作用和效果明显大于边墙部位的锚杆,二次衬砌砼承载结构所受到的压力约为其同部位围岩压力的1/3～1/2.图8,参8.

According to dogging monitoring for the exit construction of Chang-Ping tunnel located in shallow-buried and weak surrounding rock area ,the characteristics of surrounding rock and composite lining structure were studied, the contents mainly include the deformation of surrounding rock, bolt axial force, ground pressure, internal force of steel arch shelf, jet concrete and secondary lining concrete structure load state and so on. The results demonstrate that the excavation method of step decomposition is more suited to the exit construction, and it can effectively restrain the deformation of weak surrounding rock, the upper bolts of tunnel arch play more significant roles than the others, the secondary lining concrete structure load is about 1/3 - 1/2 ground pressure of the same position. These experiences can be referred to similar tunnels for the informational design and construction. 8figs., 8refs.