大型基坑坑外降水对邻近隧道的变形特性影响研究

Deformation Impact Research of Large Foundation Pit Precipitation on Adjacent Tunnel

以典型工程实例为背景,考虑土层与衬砌的相互作用,探讨了基坑开挖过程中对邻近隧道的影响,且着重对既有地铁隧道位移受坑外水位下降的敏感性进行分析。研究结果表明:基于流固耦合作用,基坑开挖对临近隧道产生了一定的影响,既有地铁四号线最大水平与竖向位移分别为-1.26 mm与-0.63 mm,均出现在靠近基坑一侧,但影响程度较小,在安全控制范围之内;坑外水位下降2 m对既有隧道变形产生了显著的影响,较坑外水位下降0 m隧道水平位移增加了34.3%,竖向位移增加了近3倍。地铁隧道位移受坑外水位下降影响显著,水平位移、竖向位移随着坑外水位下降深度的增加而增长,近似呈线性关系。

This paper, taking a typical engineering examples as a study case, discusses the influence excavation pro-cess on adjacent tunnel by taking the interaction of soil and lining factors into consideration, and focuses on analyz-ing the existing subway tunnel displacement sensitivity by the pit water levels fall. The results showed that under the fluid-structure interaction effect, excavation has a certain influence on adjacent tunnel as both the maximum horizon-tal and vertical displacement subway line 4 is 1.26 mm and 0.63 mm respectively near the side of foundation pit, which is within the security control range. When the pit water level drops to 2 m, there is a significant effect on the deformation of tunnel as tunnel horizontal displacement increased by about 34.3%and the vertical displacement in-creased about 2 times compared with the pit water level drops 0 m. There is an approximate linear relationship be-tween displacement of subway tunnel and the pit water level drop as horizontal displacement and vertical displace-ment increases along with water level drop depth.