特大断面大跨度隧道围岩变形的现场试验研究

 结合广州龙头山双洞八车道高速公路隧道工程实践，对特大断面大跨度隧道施工中围岩变形进行相关监测，分析变形随时间变化规律、不同开挖工序引起的纵向和径向空间围岩变形规律。研究结果表明：特大断面大跨度隧道采用双侧壁导洞法施工，能较好地控制围岩变形；在特大断面大跨度隧道施工过程中，右导洞上台阶、左导洞下台阶以及核心土开挖对围岩变形影响较大，是施工主要控制点；特大断面大跨度隧道开挖的纵向影响距离大致为一倍洞径左右，与导洞跨度基本相同，为6～8 m；洞顶垂直向径向影响距离约为25 m，左导洞顶30°方向的径向影响距离约为15 m。该研究结论可为类似条件下特大断面大跨度隧道设计施工和现场监测提供借鉴与参考。

IN-SITU TEST ON SURROUNDING ROCK DEFORMATION IN SUPER- LARGE SECTION AND LARGE-SPAN TUNNEL

According to construction of Longtoushan two bores and eight lanes tunnel with super-large section and span in Guangzhou，the monitoring of surrounding rock deformation was carried out. Based on the measured data，the law of the deformation varying with time and the longitudinal and radial incidences of different construction procedures were analyzed. It is shown that the surrounding rock deformation can be better controlled using the two-side pilot drifting method. During the construction of super-large section and span tunnel，the excavation of the upper bench in the right drift，the down bench in the left drift and core rock have great influence on surrounding rock deformation，which are the main stages to control the surrounding rock deformation. The longitudinal incidence of the excavation of the super-large section and span tunnel is about one time of the drift diameter，about 6 to 8 m. And the radial incidence in the vertical direction of the ceiling is about 25 m and radial incidence in the 30° direction of the ceiling in the left drift is about 15 m. The experience and conclusions presented can be used as reference in the design，construction and site monitoring of similar tunnels.