基于FLAC的导水断裂带分布规律模拟研究

Simulation study on distribution law of water flow crack zone based on FLAC

为了掌握煤层开采后上覆岩体导水断裂带的分布规律,采用FLAC有限差分程序分析不同开采宽度采空区上方应力变化。根据摩尔-库仑准则,以开采上边界起到模型单元应力状态屈服区的最高点处的距离作为导水断裂带的高度。对某矿首采工作面建立FLAC模型,模拟不同采宽条件下导水裂缝分布,结果表明:随着工作面的推进,导水断裂带先呈扁平拱形,后呈马鞍形;导水断裂带高度初期随工作面宽度增大而增大,当工作面宽度大于一临界值后不再增加;所模拟导水断裂带高度与实测吻合。回归分析表明,在相同采厚条件下,导水断裂带高度与开采宽度呈二次函数关系。

In order to master a distribution law of the water flow crack zone in the overburden strata after a seam mining,a FLAC finite difference program was applied to analyze the stress variation above the goaf with different mining width. According to the Mohr- Coulomb criterion,a distance from the mining top boundary to the highest point of the single element stress yield zone in the model would be the height of the water flow crack zone. A FLAC model was established as the first coal mining face of a mine to simulate the water flow crack distribution under the condition of different mining width. The results showed that with the advancing of the coal mining face,the water flow crack zone would be in a flat arch firstly and would be in a saddle- shape lately. The height of the water flow crack zone at the initial period would be increased with the width of the coal mining face increased and would not be increased when the width of the coal mining face was over a critical value. The simulated height of the water flow crack zone was fitted with the actual measured height. The regression analysis showed that under the condition of the same mining thickness,the height of the water flow crack zone and the mining width would be in a quadratic function relationship.