下伏采空区对水库坝基稳定性和渗漏性的影响

Influence of goaf on the stability and leakage of reservoir dam foundation

结合延安某拟建水库的工程地质条件及采空区赋存状况,在分析房柱式采空区变形破坏形式及机理的基础上,分析了房柱式采空区对拟建水库坝基的稳定性及渗漏性的影响。稳定性分析认为:拟建场地采空区处于不稳定状态,在坝体荷载作用下,将引起采空区"活化",采空区对坝基及泄水涵洞等附属构筑物的稳定存在严重影响。渗漏分析认为,下伏采空区对拟建水库渗漏存在严重影响。在采空区未发生大面积拱冒、切冒破坏的前提下,采空区引起拟建水库的渗漏量为1 671.9 m3/d,约占水库年平均流域径流量的17.9%。当采空区发生大面积拱冒、切冒破坏条件下时,采空区产生的切冒破坏将引起坝基及两侧坝肩的绕流,在切冒陷落区与不扰动区接触带出现台阶,垂直坝基轴线方向形成上下游贯通裂缝或空洞,形成管涌破坏,导致坝体失稳。鉴于此,应对坝基采空区进行有效治理,以确保建设工程安全。

Combined with the engineering geological condition of Yan’an reservoir and a proposed goaf occurrencecondition, on the basis of the analysis of the forms and the mechanism of destruction and deformation of goaf ofroom and pillar mining, the paper analyzes the influence of room and pillar goaf on the stability and leakage of thedam foundation of reservoir. The results of stability analysis show that the goaf is in an unstable state, under actionof dam load, the goaf will be “activated” and seriously impact the stability of dam foundation, sluicing culvert andother auxiliary structures. The results of leakage analysis results show that the goaf is a serious impact on theleakage of reservoir. When there is no destruction induced by arch caving and roof collapse at large area in the goaf,the leakage caused by the goaf is 1 671.9 m3/d, about 17.9% of the average annual runoff of reservoir watershed.When arch caving and roof collapse occur at large area in the goaf, the destruction induced by arch caving and roofcollapse in the goaf will cause turbulent flow in dam foundation and at the two sides of the dam abutment, a stepwill occur at the contact zone of the collapse area and non-disturbed zone, at the direction perpendicular to the damfoundation axis, upstream and downstream through cracks or void will be formed, forming piping-induced destructionand causing the instability of the dam body. In view of this, efficient control should be conducted for the dam foundation at the goaf so as to ensure the safety of the construction project.