Deformation response characteristics of karst mountains with deep and large fissures under the condition of underground mining
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摘要: 为了研究岩溶山区地下采矿活动对上覆岩层及山体的变形影响，依托贵州纳雍普洒“8.28”特大崩滑案例，在现场地质调查的基础上，分析了纳雍普洒“8.28”崩塌体特征和山体变形发展过程，采用UDEC离散元数值方法研究了地下采动作用诱发强烈岩溶山体崩滑失稳过程及变形特征。结果表明：山体上部灰岩溶蚀强烈，形成众多裂隙和岩溶管道，在地下采动作用下经历了较长的变形发展过程；地下采动影响下，山体上覆岩层向采空区方向变形，并随着顶板岩层冒落，岩层变形显著增大；上覆岩层深大裂隙对山体变形有重要影响，上部岩层沿着裂隙向下形成沉降带，同时裂隙也得以扩展；崩塌区前缘岩体由于开挖卸荷，向坡外发生挤出变形，前缘阻滑力降低；随着采空区不断扩大，山体稳定性不断降低，最终山体整体溃屈，发生破坏。普洒崩滑模式为“山体后缘拉裂沉陷—裂隙扩展贯通—整体溃屈”。本研究为开展西南地区地下采动对岩溶坡体稳定性影响评价提供借鉴。Abstract: To investigate the influence of underground mining activities on the deformation of overlying strata and mountains in karst mountainous areas, the “8.28” landslide in the Pusa community in Nayong County of Guizhou is taken as an examplein this paper, and on the basis of field geological survey, the characteristics of the collapse body and the deformation development process of the mountainsare expounded. The UDEC discrete element numerical simulation is used to simulate and analyze the process and mechanism of landslide instability induced by mining in underground mines. The results show that this mountain karst erosion is strong, there are many ground fissures and karst collapse pits, and rock mass is broken. Before the collapse, the rock mass has experienced a long deformation development process, which was obviously affected by underground mining operation. The overlying strata of the mountain deform towards the direction of goaf under the underground mining operation. With the roof rock falling, the rock deformation increases significantly. Deep and large karst mountain fissures in the overlying strata have important effects on mountain deformation. After mining, the upper rock layer forms a subsidence zone along the fissures and the fissures expand. As a result of excavation unloading, the leading edge rock mass in the collapse zone extruds out of the slope, and the resistance sliding force of the leading rock mass decreases.With the continuous expansion of the goaf, the stability of the mountain continues to decline, the final overall collapse and destruction occur. The landslide mode of Pusais thought to be “pull crack subsidence at the back edge of mountain-fissure spreading through-overall collapse”. This study is of great significance for the evaluation of the influence of underground mining on the stability of karst slopes in southwestern China.
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Key words:
- slope engineering /
- underground mining /
- numerical simulation /
- karst /
- deep and large fissures
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