富水砂性地层中地铁盾构下穿铁路施工引起的沉降分析

Settlement Analysis Caused by Metro Shield Tunneling Through Railway in Water-rich Sandy Stratum

以富水砂性地质条件下某地铁区间盾构隧道下穿铁路施工工程为背景,研究下穿施工引起地表沉降的规律。首先对Peck方程进行分析,提出地表差异沉降系数的概念,用于表征盾构施工引起的地表最大差异沉降。然后利用数值模拟方法分析地层损失率、隧道埋深、地层加固等因素对铁路设施沉降的影响规律。结果表明:地层损失率在0.5%~3.0%变化时,减小地层损失可以同时降低地表沉降及差异沉降,控制地层损失率在1.0%以内,可满足铁路设施变形控制标准;增大隧道埋深可以降低地表最大沉降量,同时可以降低地表最大差异沉降;对隧道周围土体注浆加固可以显著降低盾构下穿铁路施工引起的铁路设施沉降。

Based on the construction of metro shield tunnel underneath railway in water-rich sandy stratum,the rule of surface settlement is analyzed.Firstly,the Peck equation is analyzed,and the conception of surface differential settlement coefficient is proposed,which is used to represent the maximum differential settlement caused by metro shield construction.Then the numerical simulation method is used to analyze the influence of ground loss rate,tunnel buried depth and stratum reinforcement on the settlement of railway facilities.The results are as follows.When the ground loss rate changes from 0.5%to 3.0%,reducing ground loss rate can simultaneously reduce the surface settlement and differential settlement,and control the ground loss rate within 1.0%,which can meet the deformation control standard of railway facilities.Increasing the tunnel buried depth can reduce the maximum ground settlement and the maximum differential ground settlement.Grouting around the tunnel can significantly reduce the settlement of railway facilities caused by shield tunneling.