建筑施工荷载引起邻近地铁隧道变形机理研究

Study on the Influence of Construction Loading on the Deformation of Adjacent Subway Tunnel

随着北京城市密度的增加,围绕地铁隧道沿线建设的工程越来越多。但是地铁隧道对周围环境变化非常敏感,所以针对复杂施工过程对邻近地铁隧道影响的研究变得非常重要。主要研究深基坑土体卸荷和高层建筑物加载引起的邻近既有地铁隧道变形的变化特征、规律和机理。首先根据隧道与建筑施工荷载的相对位置关系归纳了4种作用模式,接着根据相似理论,按4种不同作用模式做了大型物理模拟试验,并采用修正剑桥模型做了相对应的数值模拟计算,最后根据不同位置施工对隧道变形影响的不同,划分了隧道变形影响区。研究结果表明:(1)在开挖阶段,各模式下隧道均向基坑方向发生位移,侧方模式中,隧道同时产生扭转。(2)在加载阶段,各模式下隧道均产生沉降;侧方浅部作用模式下,隧道会产生远离基坑的水平位移,其余侧方模式隧道水平位移均向基坑方向。(3)侧方模式中,隧道水平位移在开挖阶段受到影响更明显;隧道竖向位移在加载阶段受到影响更明显。(4)侧方模式中,在竖向卸荷量与加载量相同时,卸荷对隧道影响更大一些。

With the increase of urban density in Beijing,more and more projects are built along the subway tunnel.However,the subway tunnel is very sensitive to the surrounding environment changes,so it is very important to study the influence of the complex construction process on the adjacent subway tunnel.This paper mainly studies the characteristic and the variation rules of tunnel deformation caused by excavation of the deep foundation and load of the high-rise buildings.According to the relative position relationship between the tunnel and the construction loading,4 modes of unloading-loading construction were summed up.Four groups of model tests and corresponding numerical simulation have been conducted based on the 4 modes.Finally,the influence area of the tunnel deformation was divided.The result shows that at the excavation stage,the tunnel moves and rotates towards the foundation pit in each mode.At the loading stage,the tunnel sinks in each mode.The tunnel laterally moves away from the foundation pit under shallow-side mode,and it moves towards the pit under other side modes.In the side modes,the horizontal displacement of the tunnel is more obvious at the excavation stage,and the vertical displacement of the tunnel is more obvious at the loading stage.And the effect of unloading on the tunnel is greater when the amount of unloading is equal to the amount of loading.