反井锚喷支护立井围岩稳定性分析

Stability analysis on surrounding rock of raise-bored vertical shaft with bolt-shotcrete supporting

针对锚喷支护在用于反井成井支护时,存在由于未区分不同地层的支护需求而存在设计保守、安全系数过高的问题,可利用数值模拟方法确定立井不同深度断面围岩支护前后的应力、位移改善程度,利用立井围岩受力特性对支护设计进行验证和优化。基于安平煤业矿区新增回风立井工程,建立了井筒支护三维有限元模型,以应力和位移指标对开挖直径为5.3 m,深132 m的基岩段反井井壁进行了稳定性分析、支护效果分析及支护方案优化。结果显示锚喷支护后立井围岩的水平位移改善程度最大可达51.37%,围岩最大主应力由拉应力变为压应力,锚杆与混凝土在不同岩层中发挥的支挡作用效果不同,围岩强度高和稳定性好的区段单独喷射混凝土支护即可达到联合支护的效果,因此可根据实际情况选择和优化支护方式。最后将数值计算结果与工程实测结果进行对比,验证了有限元分析在立井围岩锚喷支护分析中的可靠性。

As the support requirements of different strata is not distinguished,the design of bolt-shotcrete support is conservative and the safety factor is too high,numerical simulation can be used to determine the improvement degree of stress and displacement of surrounding rock before and after support in different depth sections of vertical shaft,and the support design can be verified and optimized using the mechanical characteristics of surrounding rock of vertical shaft.A three-dimensional finite element model of shaft support is established based on the new air return shaft project in Anping Coal Mining Area.The stability and support effect are analyzed and the support scheme is optimized according to the stress and displacement indexes of the raise-bored shaft wall in the bedrock section with excavation diameter of 5.3 m and depth of 132 m.The results show that the horizontal displacement of surrounding rock of the vertical shaft can be improved by up to 51.37%after the bolt-shotcrete support,the maximum principal stress of surrounding rock changes from tensile stress to compressive stress.The supporting effect of the bolt-shotcrete in different rock strata is different,the section with good strength and stability of surrounding rock can achieve the effect of combined support by shotcreting,so the support method can be selected and optimized according to the actual situation.Finally,the numerical calculation results are compared with the measured results of project,and the reliability of finite element analysis in analysis of surrounding rock bolt-shotcrete support of shaft is verified.