基于三线性应变软化模型的综采工作面煤壁片帮深度解析预测

Analytical solution of predicting rib spalling depth of fully-mechanized coal working face based on tri-linear strain softening model

为预测综采工作面煤壁片帮深度,以煤壁为研究对象,煤壁煤体视作三线性应变软化材料;将直接顶和基本顶视作宏观顶板,建立了宏观顶板与煤层、支架相互作用的承载力学模型,结合边界条件推导了综采工作面煤壁片帮深度解析计算公式,利用该公式研究上湾煤矿12401工作面煤壁片帮情况,分析影响煤壁片帮的因素及影响规律,结果表明:①推导获得的煤壁片帮深度计算公式能够较准确计算综采工作面煤壁片帮深度,能够定量分析顶板特性和支架参数等对煤壁片帮深度的影响。②增加支架初撑力能够降低煤壁片帮深度;增加支架刚度能够降低煤壁片帮深度,但效果较差;增加支架护帮板支护强度,煤壁片帮深度近似线性减小。③顶板厚度和抗拉强度增加,煤壁片帮深度增长,但增长速率随顶板厚度和抗拉强度增加逐渐趋缓。这主要由于顶板厚度和抗拉强度增加,顶板破断步距增大,向采空区内旋转下沉角度增大所致。④综采采高对煤壁片帮深度有很大影响,综采采高增大,煤壁片帮深度近似线性增长。⑤煤体单轴抗压强度增大,煤壁片帮深度减小,顶底板与煤层界面之间的摩擦因数增大,煤壁片帮深度减小。⑥顶板动载系数增大,煤壁片帮深度近似线性增大。

In order to predict rib spalling depth in fully-mechanized mining faces,taking the coal wall as the research object,the coal wall is regarded as a tri-linear strain softening material.Then the direct roof and main roof are taken as macro roof,and the bearing mechanical model for the interaction between macro roof,coal seam,and support is established.Combined with the boundary conditions,the analytical solution of rib spalling depth in fully mechanized mining faces is derived in this paper.The analytical solution was used to investigate the situation of coal wall spalling in the 12401 working face of Shangwan Coal Mine,and the factors and laws influencing coal wall spalling were researched.The results show that:①The analytical solution of rib spalling depth in the fully mechanized working face in this paper is reliable and reasonable,and can quantitatively investigate the effects of roof characteristics and support parameters.②Increasing the initial support force can reduce rib spalling depth.Increasing the stiffness of the support can reduce rib spalling depth,however the effect is poor.The supporting strength of the support protective plate,and the rib spalling depth decreases approximately lin-early.③With the thickness and tensile strength of the roof macroscopic increasing,the rib spalling depth increases.However its growth rate gradually slows down.The main reasons are that the periodic fracture length increases with increment of the thickness and tensile strength of the roof,which leads to increment of the angle of rotation and sinking towards the goaf.④The mining height has a significant effect on the rib spalling depth.The rib spalling depth linearly increases with the mining height.⑤With uniaxial compressive strength of coal increasing,the rib spalling depth decreases.With the interface friction coefficient between the roof and the coal increasing,the rib spalling depth decreases.⑥With the dynamic loading coefficient of the roof increasing,the rib spalling depth increases linearly.