杭州软土地质条件下基坑开挖对邻近隧道影响分析

Analysis of Foundation Pit Excavation’S Influence Towards Adjacent Tunnels Under Soft Soil Geological Conditions in Hangzhou

目前杭州地铁总线网规划已有13条,总长562 km。随着杭州各类基坑工程的发展,如何保护地铁隧道显得更为紧迫。本文在研究杭州地区十几个近邻隧道的基坑工程案例中,分析了各因素的影响效果,包括相对距离、开挖深度、基坑开挖空间时间效应、土体加固和施工条件等影响,将各类影响因素划分为可变因素和非可变因素,可以得出具体的影响规律。研究得出以下结论:基坑开挖过程中影响邻近隧道位移,过程中水平位移相较竖直位移往往更大;隧道与基坑的水平距离与隧道的变形呈现幂函数关系,而两者高差却无明显规律,且杭州地区下基坑开挖的影响范围明显大于其他地区;基坑开挖深度作为影响隧道位移的重要因素,在初期成明显正比关系,后期曲线逐渐平缓,基坑深度较大时隧道位移则出现较大波动性。综合各类影响因素分析,可以帮助我们规范控制标准,并采取相关的控制措施,切实有效保护基坑周边隧道的正常通行。

At present,there are 13 metro lines in Hangzhou with a total length of 562 km.With the development of various foundation pit projects in Hangzhou,how to protect the subway tunnel becomes more urgent.In this paper,the effects of various factors,including relative distance,excavation depth,space-time effect of foundation pit excavation,soil reinforcement and construction conditions,are analyzed in more than a dozen cases of foundation pit projects in Hangzhou area.Various factors are divided into variable factors and non-variable factors,and the specific influence rules can be obtained.The following conclusions are drawn:during the excavation of foundation pit,the displacement of adjacent tunnels is affected,and the horizontal displacement is larger than the vertical displacement;the horizontal distance between the tunnel and the foundation pit is a power function relationship with the deformation of the tunnel,but the height difference between the two is not obvious,and the influence range of the excavation of the foundation pit in Hangzhou area is obviously larger than that in other areas;the excavation depth of the foundation pit is the position of the tunnel.The important factors of displacement are obviously proportional in the initial stage,and the curve is gradually smooth in the later stage.When the depth of foundation pit is large,the displacement of tunnel will fluctuate greatly.Comprehensive analysis of various influencing factors can help us standardize control standards and take relevant control measures to effectively protect the normal passage of tunnels around foundation pits.