地铁车站多工法施工的地层变形研究

Research on deformation of surrounding rock of subway station multimethod construction

以重庆交通轨道环线冉家坝地铁车站为工程依托,采用现场监控量测方法研究了双侧壁导坑法开挖、侧洞法开挖及明挖法施工下的地层变形规律。结果表明:3种工法下明挖法引起的地表沉降变形最小,双侧壁导坑法开挖次之,侧洞法引起的沉降变形最大;2种暗挖施工下初次开挖扰动引起的地层变形最大,占总沉降量的50%以上。分析隧道拱顶变形发现,变形过程可分为左导洞开挖后的快速沉降阶段、左右导洞开挖及时支护后的过渡变形阶段和临时支撑拆除后稳定变形阶段,且2种暗挖工法下的拱顶变形曲线均可由指数函数拟合。

As an example of a certain constructing Ranjiaba subway station of Chongqing transit circle line,by sitemonitoring method,the deformation characteristics of surrounding rock affected by the subway station with multimethod construction are studied.The results show that the deformation induced by open cut method induces issmaller than the deformation induced by the double side drift method and side drifts-support method,and the firststratum deformation caused by the two kinds of underground construction is more than50%of the total settlement.Also,cures of crown settlement ts obtained by in-situ convergence deformation measurement can be characterizedinto three phase:rapid deformation phase after the left tunneling,transition phase,due to the working of preliminarybracing;and stable convergence phase after the temporary support dismantled.Regression analysis was carried outon the deformation of surrounding rock,and the results show that exponential function fit the dates obtained fromin-situ monitoring better than other functions.