明挖隧道深基坑受力与变形的现场测试分析

Analysis on In-situ Testing about Stress and Deformation about Deep Foundation Pit in Open Cut Tunnel

基坑稳定性是城市浅埋明挖隧道施工的重要控制节点。通过对福州市某隧道工程中的一段深基坑工程地表沉降、临近建筑物沉降、土层水平位移、支撑轴力和基坑水位的监测,对因基坑开挖而引起的变形与结构受力等规律进行分析,并且研究了水位变化的变形特性。监测分析表明:基坑的水位变化随开挖时间的渐变过程经拟合后近似二次抛物线型;周边建筑物沉降随开挖时间的递增而增大,增长速度前期慢后期快,最终趋于稳定。该明挖隧道深基坑工程支护结构的基坑变形控制设计方案是合理可行的,可为类似工程提供经验借鉴。

The stability of foundation pit is an important control node in city shallow buried and open cut tunnel construction. Through the monitoring of surface settlement,ambient buildings settlement,horizontal displacement of soil,strut axial forces and foundation pit water level of a section of deep foundation pit in a tunnel construction in Fuzhou city,the laws of deformation and struction stress cased by foundation pit excavation are analysed,and the deformation characteristies of water level change is studied. The monitoring analysis shows that： the fitting curve of water level changing with the excavation time is close to the quadratic parabola. The settlement of the around buildings increases with the excavation time. The increment speed is slower in the earlier stage,and faster in the later stage,and finally reaches steady state. The design scheme of foundation pit deformation control about the foundation pit supporting structure in the open cut tunnel is reasonable and feasible,and it can provide the experience and reference for similar projects.