顶板崩落变形破坏过程的数值分析

Numerical Analysis for the Deformation Failure Process of Roof Caving

采用数值方法建立三维计算模型,分11个步骤对采场开挖的全过程进行数值模拟,得到开挖后空区围岩的水平位移、竖向位移和塑性区分布情况,进而分析矿区顶板自然崩落规律的变形破坏情况。由于采场的开挖,导致岩体内部应力释放,围岩位移指向空区内部,水平位移最大处出现在采场采矿区的两侧边帮处,位移方向均指向采空区内部。随着开挖宽度的扩大,竖向位移呈圆弧曲线形式由采场顶板向岩体内部不断扩张。开挖过程中,空区顶板首先由剪切破坏导致岩体破裂下落,出现采场顶板冒落现象,采场采空区的顶板中央上部岩体随着顶板冒落不断往下变形,出现一定高度破坏区域的岩体。当采场开挖面积进一步扩大时,采场顶板上方的岩块将无法维持稳定状态,出现持续崩落现象。

Numerical method is used to build a three-dimensional calculation model for numerically simulating the whole excavation procedure in the stope by 11 steps.By this method,the distribution of horizontal displacement,vertical displacement and plastic zone of surrounding rock in mined-out area after excavation is obtained and then the deformation and failure of the natural roof caving in the mining area is analyzed.The excavation of the stope leads to the release of internal stresses in rock mass,and the displacement of rock mass directs to the internal part of goaf.Maximum horizontal displacement occurs at the two sides of mining area in the stope and it directs to the intemal part of goaf.With the expansion of the excavation width,the vertical displacement expands from the stope roof to the inside of rock mass in the form of arc curve.During the excavation,the rock of goaf roof falls due to the shear failure,therefore,the roof caving occurs.And the rock mass in the upper central part of the goaf roof deforms downward continually with the roof caving happening,hence,a certain height of damaged rock mass occurs.When the area of excavation expands further in the stope,rocks above the stope roof will not remain stable and continue to fall down.