厚煤层坚硬顶板沿空留巷预裂深度对围岩影响研究

Study on Influence of Pre-splitting Depth of Gob-side Entry Retaining on Surrounding Rock in Thick Coal Seam with Hard Roof

为控制工作面回采后沿空留巷围岩变形量,以永宁煤矿10202工作面为研究背景,分析了大采高厚灰岩坚硬顶板条件下预裂深度对沿空留巷围岩变形的影响:预裂深度主要影响基本顶断裂位置,切断巷道顶板与采空区岩层应力传递,减小基本顶回转下沉变形。构建不同预裂深度力学模型,相同支护条件下,预裂深度达到基本顶边界与在直接顶内预裂,巷道顶板下沉量分别为0.72 m和1.12 m。数值模拟结果表明,随着预裂深度的增加,围岩变形减小,实体煤承压范围增大,应力集中峰值减小。现场留巷试验后顶底板移近量约为0.7 m,围岩变形得到有效控制。

In order to control the deformation of surrounding rock of gob-side entry retaining after working face mining, taking 10202 working face of Yongning coal mine as the research background, the influence of pre-splitting depth on the deformation of surrounding rock of gob-side entry retaining under the condition of hard roof of thick limestone with large mining height was analyzed. The pre-splitting depth mainly affects the fracture position of basic roof, cuts off the stress transfer between roadway roof and goaf rock, and reduces the rotary subsidence deformation of basic roof. The mechanical model of different pre-splitting depth is constructed. Under the same supporting condition,the pre-splitting depth reaches the basic roof boundary and pre-splitting in the direct roof, and the roof subsidence is 0.72 m and 1.12 m respectively. The numerical simulation results show that with the increase of pre-splitting depth, the deformation of surrounding rock decreases, the bearing range of solid coal increases, and the peak value of stress concentration decreases. The displacement of roof and floor is about 0.7 m after the field roadway retention test, and the deformation of surrounding rock is effectively controlled.