邻近隧道的岩质深基坑开挖影响研究

INFLUENCE STUDY OF DEEP ROCK FOUNDATION PIT EXCAVATION ON ADJACENT TUNNELS

目前基坑开挖对邻近隧道的影响研究主要集中于软土地层,在土岩组合地层当中研究较少。以重庆临江门开挖深度近30 m、邻近隧道的岩质深基坑工程为例,运用数值模拟方法与工程现场监测成果对基坑开挖所造成的影响进行分析研究。研究结果表明:岩质基坑变形总体较小,支护桩加分阶预留岩墙作为围护体系比较有效,支护结构变形主要集中于土层部分;有邻近隧道时,拱圈所对应支护桩弯矩比无隧道时要大,直墙段所对应支护桩弯矩比无隧道时要小;由于受连续介质及隧道几何形态的影响,隧道会改变位移场传递的方向,并且竖直方向改变大于水平方向,隧道主要表现为横向变形。衬砌拱顶、左拱脚、左墙中的弯矩明显增加,隧道具有明显的偏压效应。

The excavation of foundation pit has influence on the adjacent tunnel. This study is mainly concerned with the soft soil layer, but less research has been done on the soil rock layer. According to the rock deep excavation at the depth of 30 m adjacent to the tunnel in Linjiangmen, Chongqing, the main monitored results combined with numerical simulation are analyzed. The results show that the deformation of deep excavation is small. The retaining pile and reserve rock wall is an effective support system. The main deformation of supporting struc^res concentrates in soil strata in rocky area. When the foundation pit is adjacent to a tunnel, the bending moment of retaining pile corresponding to the arch ring is larger than that when there is no tunnel, but it corresponding to the wall section is smaller than that when there is no tunnel. Due to the influence of the continuous media and tunnel geometric shape, the tunnel will change the direction of the displacement field. The vertical displacement is larger than the horizontal displacement, the lateral deformation will appear. The bending moment ofttmnel vault, left arch springing and left wall has a bigger increase. The tunnel has obvious bias effect.