巷道顶板三维板梁结构的传力机制研究

Study on force transfer mechanism of roadway roof with three-dimensional plate girder structure

为了揭示巷道开挖前后,巷道顶板三维板梁结构内应力场的演化规律,通过建立层状岩层的承载传力力学模型,研究了层间结构面和层状岩体变形对承载和传递应力的扰动作用,提出了层间结构面和层状岩体承载传力的能量分析方法,确定了层状岩体的应力传递和应变能密度解析解,揭示了结构面储能和层状岩体承载传力的影响规律,并在淮南张集矿1412A工作面开展工程应用。结果表明:法向刚度和切向刚度决定了层间结构面的储能能力,法向应力和切向应力决定了结构面的实际储能大小;岩层的承载应力并非等于上部岩层的负重,而是上部岩层的作用应力、自重应力、下位岩层的作用应力叠加的结果;应力传递效率与相邻上下层岩层的容重比呈正相关关系,与层厚比呈负相关关系,与弹性模量比呈负相关关系;1412A工作面开采时,1#煤顶板第1层薄的软弱泥岩无法承载上方岩层的重量,第2层厚的中砂岩可以承载上方岩层及自身重量,载荷应力为0.90 MPa,计算得到该类条件下基本顶初次断裂步距为30.7 m,与现场实测结果基本一致。

In order to reveal the evolution laws of the internal stress field in roadway roof with the three-dimensional plate girder structure before and after the roadway excavation,through establishing the mechanical model on load-bearing force transfer of bedded rock formation,the disturbance action on the load-bearing and transfer stress by the interlayer structure plane and bedded rock deformation was studied.The energy analysis method of interlayer structure plane and load-bearing force transfer of bedded rock was proposed,and the analytical solutions of stress transfer and strain energy density of bedded rock were determined.The influence laws of energy storage of structural plane and load-bearing force transfer of bedded rock were revealed,and the engineering application was carried out on 1412A working face in Zhangji Coal Mine in Huainan.The results showed that the energy storage capability of interlayer structure plane depended on the normal stiffness and tangential stiffness,and the practical energy storage capability of structure plane depended on the normal stress and tangential stress.The load-bearing stress of rock formation was the superposition result of applied stress of upper rock formation,geostatic stress and applied stress of lower rock formation,rather than the loading weight of upper rock formation.The stress transfer efficiency was positively correlated with the volume-weight ratio of neighboring upper and lower rock formation,and was negatively correlated with the layer thickness ratio and elastic modular ratio.During the mining on 1412A working face,the thin weak mudstone in the first layer of one coal roof could not bear the weight of above rock formation,while the thick medium sandstone in the second layer could bear the weights of above rock formation and itself,and the loading stress was 0.90 MPa.The first breakage drawing pace of old roof under the similar conditions obtained by the calculation was 30.7 m,which was in agreement with the measured data in field.