均布荷载下小净距浅埋偏压隧道双侧壁导坑法工序优化分析

对具有断面跨度大、净距小、埋深浅、偏压、围岩稳定性差和下穿建筑等特点的隧道,如何减小和控制地表沉降成为施工中考虑的关键技术问题。基于双侧壁导坑法,建立FLAC3D有限差分三维数值模型,对8种开挖工序所产生的拱顶沉降、建筑所处地表位移、塑性区面积和类型进行对比分析。结果表明:左右侧导洞开挖对拱顶沉降影响较小,中间导洞上台阶开挖时,拱顶沉降最大,能占到总沉降的40%左右;优化后的工序要点为优先开挖深埋侧隧道,并优先开挖其浅埋侧导洞。研究结果可为该类隧道的设计与施工提供理论支撑。

Analysis on Process Optimization of Double Side Drift Method of Small Spacing Shallow Embedded Bias Tunnels under Uniformly Distributed Loads

How to reduce and control the ground subsidence is a key technical problem in the construction of tunnels with the characteristics of large span,small spacing,shallow buried depth,bias,poor stability of surrounding rock and underneath buildings and so on.Based on the double side drift method,the finite difference three-dimensional numerical model of FLAC3D was established,the crown settlement,the surface displacement of buildings and the area and type of plastic zone produced by eight excavation procedures were compared and analyzed.The results showed that left and right side of pilot tunnel excavation had little influence on the settlement of vault,the vault settlement was the largest when central pilot step excava-tion,which could account for about 40% of the total settlement.The process point after optimization was to excavate deep embedded side tunnel and shallow embedded side pilot drift preferentially.The research re-sults can provide theoretical support for the design and construction of such tunnels