基于薄板理论的孤岛工作面基本顶变形规律及破断距研究

Study on deformation law and breaking span of main roof of isolated working face based on thin plate theory

为研究三面环空孤岛工作面基本顶的变形及破断规律,以河南某煤矿MZ201工作面为研究背景,通过弹性薄板小挠度弯曲理论,构建了基本顶破断力学模型,分析了工作面基本顶的破断力学特征,得到了基本顶初次来压和周期来压步距。研究结果表明:初次来压时,基本顶岩层变形较小,顶板下沉量最大点位于采空区中后部,变形量为360 mm;周期来压时基本顶岩层变形较大,顶板下沉量最大点位于基本顶中心,变形量为807 mm;初次破断时,岩层最先从两长边中部发生拉伸破坏;周期破断时,基本顶从下表面中心位置开始破断,后沿倾向方向不断发展,在短边近端处分叉,形成“X”型破断;基于拉应力破断准则计算得到基本顶初次破断距和周期破断距分别为49.3 m和27.9 m。

To study the deformation and fracture laws of the main roof in three-side annular island working face,the MZ201working face of a coal mine in Henan Province was considered as the research background,and a main roof breaking mechanics model was constructed by using the small deflection bending theory of elastic thin plate.The fracture mechanics features of the main roof of the island working face were analyzed,and the initial pressure and periodic pressure breaking span of the basic roof were obtained.The results show that the deformation of the main roof is small during the initial pressure,and the maximum roof subsidence is 360 mm in the middle rear area of the goaf.During periodic pressure,the deformation of the main roof is large,especially in the center of the roof,and the maximum roof subsidence is 807 mm.The tensile failure of rock strata first occurs from the middle of the two long sides at the first breaking.During periodic breaking,the rock strata starts to break from the center of the rock strata bottom,develops continuously along the dip direction,forks at the near end of the short side,which contributes to the“X”type breaking.Based on the tensile stress fracture criterion,the initial breaking span and periodic breaking span of main roof were obtained with 49.3 m and 27.9 m,respectively,which is closed to measured results on site.