龙首矿充填体悬臂结构的稳定性分析与评价

Stability Analysis and Evaluation of Filling Cantilever Structure in Longshou Mine

安全是矿山生产中极其重要的一环,充填体悬臂结构是龙首矿进路回采中十分常见的安全隐患形式,由于自重和深部地应力的作用,容易发生崩塌破坏现象。根据龙首矿实际情况,其充填体悬臂结构失稳破坏主要有崩落式和拉裂—坠落式2种形式。基于悬臂梁理论,建立进路人工假顶悬臂和充填围岩悬臂力学计算模型,通过理论计算悬臂极限长度、数值模拟验证和稳定性系数K并进行综合评价,以保障矿山安全生产。结果表明:充填体悬臂的稳定性受顶部裂缝深度比和实际长度的影响,其极限长度与数值模拟结果基本一致。同时,稳定性系数K能够有效统计不同裂缝条件下充填体悬臂状态,判断充填体悬臂顶部裂缝深度比情况。因此,悬臂极限长度和稳定性系数K能够有效评价龙首矿充填体悬臂的稳定性,实际应用简单,计算结果与现场调查情况基本吻合,对于潜在的充填体悬臂结构安全隐患能起到及时预警的效果。

Safety is an extremely important part of mine production.The cantilever structure of filling body is common form of potential safety hazard in drift stoping of Longshou mine.Collapse is easy to occur due to self weight and deep in-situ stress.Longshou mine is the only large underground mine in China that successfully adopts panel area mechanized downward hexagonal drift cemented filling mining method,its artificial false roof cantilever and filling cantilever surrounding rock often collapse by itself.At the same time,the deep filling body has large deformation,which brings great instability and hidden dangers to the safety production of the mining area.In order to effectively deal with and comprehensively evaluate the cantilever stability of backfill,based on the cantilever beam theory and combined with the experience of geotechnical dangerous rock mass,this paper established the mechanical models of artificial false roof cantilever and surrounding rock filling cantilever in Longshou mine,and studied the calculation methods of collapse and tension crack fall deformation and failure modes.Thus,the limit cantilever length and stability coefficient K of filling body were proposed.The limit length of cantilever was calculated theoretically,verified by numerical simulation and stability coefficient K.The results show that the stability of the filling cantilever is negatively correlated not only with the limit length of the cantilever,but also with the development of the overlying crack.Through the simulation,the tensile strength of the failure condition is basically the same between the theoretical limit length and the simulated length.It shows that the theoretical limit length is suitable for the actual geological conditions of Longshou mine.At the same time,the stability coefficient K can effectively count the cantilever state of the filling body under different crack conditions,and judge the crack depth ratio at the top of the cantilever of the filling body according to the actual state of the cantilever on site and in combination with the stability evaluation grade classification table.Therefore,the cantilever limit length and stability coefficient K can effectively evaluate the stability of the filling cantilever in Longshou mine.The practical application is simple,and the calculation results are basically consistent with the field investigation results.It can play a timely early warning effect for the danger caused by the excessive cantilever and the further development of cracks.It has guiding significance for the safety production of drift mining in Longshou mine.