武汉岩溶区复合地层小型盾构施工引起的地表变形规律研究

Study on Surface Deformation Pattern Caused by Small Shield Tunneling in Complex Strata in Karst Area of Wuhan

小型盾构施工法是目前电力隧道施工的主要工法,在施工过程中不可避免地会引起地面沉降,影响附近建筑物的正常使用。为揭示武汉岩溶地区复合地层小型盾构施工引起的地表变形规律,在对现场勘察资料和地表变形监测数据进行统计分析的基础上,采用数值模拟的方法对不同组合复合地层、不同溶洞直径和不同溶洞埋深时的地表变形规律进行了数值模拟计算与分析。结果表明:岩层表面距隧道底板深度Z、溶洞距隧道底板高度H、隧道底板下溶洞直径D等对地表变形均有重要的影响;随着Z和D值的增加,地面沉降量最大值增加,随着H值的增加,地面沉降量最大值减小。在岩溶区复合地层开展小型盾构施工时,上软下硬的地层分布会产生应力集中现象,将会增大地表竖向变形。本研究为控制岩溶区复合地层小型盾构施工地表变形提供依据。

Small shield tunneling is the main construction method of power tunnel at present,which will inevitably lead to surface deformation and affect the normal use of adjacent building during the construction process.In order to reveal the surface deformation law caused by small shield tunneling in the complex strata in karst area of Wuhan,this paper applies the numerical simulation method to analyzing the surface deformation laws under different composite strata,different diameters of karst cave and different burial depths of karst cave on the basis of field investigation and surface deformation monitoring data.The results show that the depth Z between the rock upper surface and the tunnel floor,the height H between the karst cave and the tunnel floor,and the diameter D of the karst cave have important effects on the surface deformation.With the increase of Z and D,the maximum land subsidence increases.With the increase of H,the maximum land subsidence decreases.When small shield tunneling is used in complex stratum of karst area,the distribution of upper soft stratum and lower hard stratum will produce stress concentration phenomenon,which will increase the vertical deformation of the surface.The study establishes a foundation for controlling the surface deformation of small shield tunneling in karst area.