考虑岩体碎胀效应的采场覆岩冒落规律分析

应用改进的岩石破裂过程分析系统(RFPA2D)，分析了煤层开采过程中上覆岩层发生离层、弯曲、端部和中部开裂直至冒落的全过程，再现了采动影响下冒落带、裂隙带、下沉带3带的形成过程以及裂隙拱的形成发展、整体覆岩的周期性运动模式。数值计算中，引入了冒落岩体的碎胀效应，使得计算结果更合理地反映了现场实际，主要表现在：冒落岩体的碎胀效应及拉伸、剪切破坏联合控制了覆岩的运动模式，随着工作面的不断推进，上覆岩层可呈现出周期性的运动特征；裂隙拱发展到一定高度后，工作面垂直方向上不再扩展，只在工作面推进方向向前扩展，此时裂隙拱拱顶为一近似水平线，冒落带、裂隙带和下沉带3带分明；覆岩运动引起的地表下沉范围和下沉量亦都更符合现场实际。

Investigation on overburden strata collapse around coal face considering effect of broken expansion of rock

Dynamic progressive process of layer separation, bending, sagging and fracturing of overburden strata induced by mining excavation is investigated based on numerical method and the improved Rock Failure Process Analysis code. The simulation result reproduces the formation of caving zone, fractured zone and bend zone. In addition the evolution of fracturing arch and the periodically common nature of strata movement are numerically obtained. It is shown that the overburden strata movement depends on the effect of broken expansion and the tension, shear failure of rock mass. Because the broken expansion of caving rock strata is employed, the fracturing arches do not expand vertically upward, but expand horizontally forward. The top of the arches keeps at the same level and the strata failure is of periodic law. The boundaries of caving zone, fractured zone and bend zone are obviously clear and the surface subsidence is more reasonable. Consequently the numerical results are more consistent with the measured data obtained in-situ.