相邻隧道扩挖施工影响分析

采用现场实测和数值计算方法,对乌鞘岭志留系地层板岩夹千枚岩地段左线隧道扩挖施工引起右线隧道的围岩状况和既有支护结构的受力变化进行分析。结果表明,两相邻隧道在不同施工阶段进行导洞开挖和扩挖前后存在一定程度的群洞效应作用,扩挖施工引起右线隧道向左线隧道产生了较小的侧移;在左线隧道扩挖后,右线隧道既有衬砌的接触压力、结构轴力和弯矩均有明显增大,但衬砌结构的安全系数均满足规范要求,处于安全状态。

Analyses on the mutual effect of enlargement excavation of two adjacent tunnels

The paper analyzed the stress variation in the supports of the left-line tunnel caused by the enlargement excavation of the right-line tunnel of Wuqiaoling tunnel on the section of Silurian slate sandwiched with phyllite by adopting numerical analyses and in-situ monitoring.Results of the analyses indicated,in the process of excavation from the heading to the enlargement the two adjacent tunnels affected each other,enlargement excavation of the left tunnel caused a small horizontal displacement of the right tunnel toward the left one,meanwhile the contact pressures,thrusts and bending moments in the lining of right tunnel increased obviously,yet the corresponding factors of safety could satisfy the requirements of the Code.