交叉中隔墙法开挖浅埋偏压隧道围岩稳定性分析

Stability Analysis of Surrounding Rock of ShallowBuried UnsymmetricalLoading Tunnel Excavated by CRD

为对比分析采用交叉中隔墙法开挖浅埋偏压隧道和常规非偏压隧道围岩稳定性的区别,以及围岩参数对其安全系数的影响,通过建立数值仿真模型,基于强度折减法对隧道围岩稳定性展开分析。研究结果表明:采用交叉中隔墙法开挖时,V级围岩浅埋偏压隧道的沉降和水平位移均随开挖面积扩大而不断增大,初期支护封闭成环后,围岩塑性应变值降低,稳定性得到显著提升,安全系数为1.6时的最大沉降值为23.83 mm;V级围岩非偏压隧道安全系数为2.2时的最大沉降值为23.71 mm,其沉降和水平位移均随折减系数增长而发展速率相对较慢,非偏压隧道的稳定性显著强于偏压隧道;随围岩级别降低,偏压隧道的沉降和水平位移均减小,安全系数提高。

In order to compare and analyze the stability differences between the shallow buried unsymmetrical and symmetrical loading tunnels were excavated by the cross diaphragm method(CRD),as well as the influence of surrounding rock parameters on the safety factors.A numerical simulation model was established to analyzes the stability of tunnel surrounding rock by the strength reduction method.The results indicate that the settlement and horizontal displacement continuously increase with the expansion of the excavation area when the shallow buried unsymmetrical loading tunnel in V grade surrounding rock excavated by cross diaphragm method.After the initial support is closed into a ring,the plastic strain value of the surrounding rock decreases,and the stability of the surrounding rock is significantly improved;The maximum settlement is 23.83 mm when the safety factor is 1.6;In V grade surrounding rock,when the symmetrical loading tunnel safety factor is 2.2,the maximum settlement is 23.71 mm.The settlement and horizontal displacement growth rate of symmetrical tunnel is relatively slow with the reduction coefficient enlarge.The stability significantly higher than that of the unsymmetrical loading tunnel;With the surrounding rock grade decreases,the settlement and horizontal displacement of the bias pressure tunnel decrease,and the safety factor increases.