顶板对称固定块体最小固定面积松弛分析

Relaxation analysis of the minimum fixed area of roof symmetric fixed block

现有顶板对称固定块体的稳定性分析,未考虑原岩夹持力与结构面断裂的影响,易造成分析结果的不准确。基于松弛分析法,分析了受夹持力时对称固定块体的受力情况,推导了结构面断裂下固定面处等效应力公式,探讨了受夹持力与结构面断裂共同影响时固定面处的联合应力分布状态,并给出了对称固定块体最小固定面积的解析解;运用PFC^(2D)软件,模拟了对称固定块体的失稳过程,对比了最小固定面积数值解与解析解结果间的差异性;对广西高峰矿105^(#)矿体某巷道顶板现场破断现象进行了实地调查。分析结果表明:(1)顶板对称固定块体的最小固定面积分别与块体高度、结构面和竖直面的夹角正相关;(2)最小固定面积的数值解与解析解结果基本一致,二者平均相对误差为7.4%;(3)夹持块体呈断裂脱落并在巷道顶板处留下可见最小固定面积,现场破断现象与松弛分析结果、数值分析结果相吻合。研究成果表明基于松弛分析法的顶板对称固定块体稳定性分析是科学合理的。

The existing stability analysis of symmetrical fixed block of roof does not consider the influence of original rock holding force and structural plane fracture,which easily leads to inaccurate analysis results.Based on the relaxation analysis method,the stress situation of symmetrical fixed block under clamping force is analyzed,an equivalent stress formula of fixed surface under the fracture of structural plane is deduced,the joint stress distribution state of fixed surface under the joint influence of clamping force and structural plane fracture is discussed,and the analytical solution of the minimum fixed area of symmetrical fixed block is given.The symmetrical fixed block is simulated by PFC^(2D)software,the difference between the numerical solution of the minimum fixed area and the analytical solution is compared,and the field investigation is carried out on the roof breaking phenomenon of a roadway in the#105 orebody of Gaofeng mine in Guangxi.The results show that:(1)The minimum fixed area of symmetrical fixed block is positively correlated with the height of block and the angle between structural plane and vertical plane,respectively.(2)The numerical solution of the minimum fixed area is basically consistent with that of analytical solution,and the average relative error between them is 7.4%.(3)The clamped block is fractured and falls off,leaving visible minimum fixed area at the roof of roadway.The results are in good agreement with the results of numerical analysis.The research results show that the stability analysis of symmetrical fixed block of roof based on relaxation analysis method is scientific and reasonable.