双孔隧道的地表沉降预测及其可靠度分析

Ground Surface Settlement Prediction and Reliability Analysis of Twin Tunnels

以合肥地铁2号线某区间段为工程背景,基于理论分析和数值模拟相结合的方法研究了双孔平行隧道掘进过程中地表纵横向沉降规律。研究结果表明:双孔隧道掘进过程中横向地表沉降发生在隧道轴线2D(D为管片直径)范围内;纵向地表沉降发生在开挖面前段2D到开挖面后段4D范围内,主要沉降区域为开挖面前段1.5D到开挖面后段2.5D之间。通过与单孔隧道沉降规律的对比,双孔隧道先行洞的施工会对后行洞产生扰动,两隧道之间存在叠加效应,在理论分析中引入叠加效应系数来体现这一影响。同时将中心点法应用于改进的Peck公式中,对地表最大沉降的平均值、标准差及其可靠度进行计算。说明了进行沉降预测和可靠性计算的必要性,为此类问题的研究提供了切实可行的分析方法。

Based on the engineering background of a section of Hefei Metro Line 2,a theoretical analysis and a numerical simulation method were used to study the vertical and horizontal settlement of the ground surface during the tunneling process with two holes.The results of the study indicate that lateral surface settlement occurs in the tunnel axis 2 D(D is the diameter of the segment)during tunneling;Longitudinal surface subsidence occurs between 2 D excavation and 4 D after excavation,and the main development area is 1.5 D excavation and 2.5 D after excavation.Compared with the single-hole tunnel settlement rule,it is found that the construction of the first hole of the double tunnels will cause disturbance to the post-entrapment tunnel,there is a superposition effect between the two tunnels The superposition effect coefficient is introduced in the theoretical analysis to reflect this effect.At the same time,the center point method is applied to the modified Peck formula to calculate the average and standard deviation of the maximum surface settlement and its reliability.It explains the necessity of settlement prediction and reliability calculation,and provides a practical analysis method for the research of such problems.