异质软硬复合地层地铁车站穿越富水断层施工响应与控制

针对异质软硬复合地层地铁车站穿越断层施工变形控制难题，对断层影响下地铁车站开挖过程中围岩力学响应进行研究，探讨不同加固方案下车站围岩变形演化规律，为复杂条件下地铁车站穿越断层施工提供理论指导。以某地铁车站穿越富水断层破碎带为背景，通过室内实验确定特殊地层围岩物理力学性质及破坏特征，结合BQ围岩分级方法确定围岩等级；在此基础上采用有限差分数值模拟软件，对比研究有无地下水影响下地铁车站开挖后围岩应力及沉降变形分布特征，采用控制变量方法研究临时支撑与注浆加固对车站围岩整体稳定性的影响，进而确定合理的施工控制方案。研究结果表明：有无地下水对于异质软硬交叉地层的围岩物理力学特性影响明显，而侵入的辉绿岩尤甚，极易产生沿节理面的剪切滑移破坏；地下水影响下车站拱顶最大沉降值为6.5mm，较之无地下水条件下增大30%；辉绿岩部分（车站右部）最大拉应力为1.62MPa，远大于其极限抗拉强度1.25MPa，故无注浆加固条件下辉绿岩侧可能产生大范围破坏；全断面注浆降低了地下水对围岩变形的影响效果显著，以65°断层为界，断层倾角越小，全断面注浆宽度应越大；基于分析结果，提出全断面注浆+临时支撑+小进尺的过断层车站安全施工方案，监测结果表明应用效果良好。

Construction Response and Control of Subway Station Crossing Water-Rich Fault in Heterogeneous Soft-Hard Composite Stratum

Aiming at the problem of deformation control of subway station crossing fault construction in heterogeneous soft and hard composite stratum, the mechanical response of surrounding rock during excavation stage was studied. And the deformation evolution law of surrounding rock under different reinforcement schemes was discussed. The result can provide theoretical guidance for the construction of subway station crossing fault, etc. Taking a subway station crossing the water-rich fault fracture zone as the background, the physical and mechanical properties and failure characteristics of surrounding rock in special stratum were determined by laboratory experiments, and then the surrounding rock grade was determined by BQ method. On this basis, the finite difference numerical simulation software was used to study the distribution characteristics of stress and deformation of surrounding rock. Combined with the control variable method, the influence of temporary support and grouting reinforcement on the overall stability of surrounding rock was studied, so as to determine a reasonable construction control scheme. The results show that the presence or absence of groundwater has obvious influence on the physical and mechanical properties of surrounding rock in heterogeneous soft and hard cross strata. Diabase is particularly affected Under construction disturbance, it is easy to produce shear slip failure along the joint surface. The maximum settlement value of the station vault under the influence of groundwater is 6.5mm, which is 30% higher than that without groundwater. The maximum tensile stress of diabase (the right part of the station) is 1.62MPa, far greater than its ultimate tensile strength of 1.25MPa. So, the diabase side may produce a large range of failure without grouting reinforcement. Full-section grouting has a significant effect on reducing the influence of groundwater and excavation disturbance on the deformation of surrounding rock. With 65° fault as the boundary, the smaller the dip angle of the fault, the larger the width of full-section grouting. Based on the analysis results, a safety construction scheme of full section grouting + temporary support + small footage is proposed. The monitoring results prove the research result to be effective in practice.