急斜煤层放顶煤开采中基本顶的溃屈破断分析

针对急斜煤层水平分段放顶煤开采过程中基本顶破坏活动对工作面的影响,应用板裂介质力学计算模型,进一步研究结构分叉后平衡路径的演化途径;应用后屈曲能量准则建立平衡稳定模态幅值方程和溃屈极限长度方程。研究表明:分叉点附近的邻域与煤层赋存条件、岩体材料及结构几何特征有关;基本顶从初始屈曲到后屈曲的变形过程中,只有当正则因子改变正负号时,系统才会从一个状态跳到另一个状态,基本顶岩体结构的后屈曲是一个由分叉点后屈曲性态到极值点后屈曲性态的耦合过程;而由倾角确定的剖分因子始终控制着系统状态变量与载荷的对应关系,影响基本顶的稳定性。

Buckling failure of roof with top coal caving in steep seem

Based on the influence of the roof failure on work face with horizontal section top coal caving in steep seam and mechanical calculation model of sheet crack,the regions near equilibrium bifurcation point and evolutions along equilibrium path were investigated.First,the equation for limit length of the roof buckling failure in all cases was established by using modality amplitude equation of equilibrium stability derived by post-buckling energy criterion.Then,the equations for modality amplitude and limit length of the roof buckling failure were established.It is shown that the stabile regions near bifurcation point have relations with the preservative condition of steep seem,the material of rock mass and the geometrical properties.In the process of roof deformation from initial buckling to post-buckling,only if canonical factor changes its plus-minus,does the system jump from one state to the other,the post-buckling of the structure rock mass is a coupling process from bifurcation point to extreme point post-buckling behavior.The ripping factor depending on steep seem angle can determine singlevalued relation between the state variate and load,also influences the stability of the roof.