双侧壁导坑法开挖Ⅴ级围岩隧道过程中地表沉降规律研究

Study on Surface Settlement Law in Excavation of V-grade Surrounding Rock Tunnel by Double Side Wall Pilot Tunnel Method

针对目前采用双侧壁导坑法开挖隧道过程中对地表沉降规律研究方面的不足,该文以福建某隧道出口Ⅴ级围岩开挖引起的地表沉降为例,首先通过现场测量得到了隧道开挖过程中地表沉降监测点的沉降值,并详细记录了对应的开挖进程。然后采用图表分析和数学统计方法得出了各导坑开挖引起的地表沉降量和沉降速率及其各项统计量。最后综合考虑隧道开挖进程及其沉降曲线走势,将整个监测过程分为7个区段,并采用曲线拟合的方式给出了沉降曲线方程。经过对各个区段曲线特征的分析发现,上部中导坑开挖对地表沉降影响最大;左右导坑开挖中,先行导坑引起的地表沉降明显大于后行导坑。

As the shortage in the study of ground surface settlement law in excavation of tunnel by double-side-heading method, and taking the ground surface settlement caused by V-grade surrounding rock excavation at the exit of a tunnel in Fujian Province as example, the article describes the surface settlement value at the ground surface settlement monitoring site in the tunnel excavation through the field measurement,and records the corresponding excavation process in detail. The surface settlement volume and velocity as well as other statistical quantities caused by the excavation of pilot tunnels are get by the chart analysis and mathematical statistics method. The tunnel excavation process and its settlement curve trend are comprehensively considered, and the whole monitoring process is divided into 7 sections. The settlement curve equation is given by the curve fitting method. According to the analysis of curve features in various sections, it is found that the influence of the top center tunnel excavation is the largest on the surface settlement, and the surface settlement caused by the first pilot tunnel is obviously larger than the secondary pilot tunnel in the excavation of left and right tunnels.