重复采动下近距离煤层群下行开采工作面矿压显现规律研究

Study on mine pressure behavior law of downward mining face in close distance coal seam group under repeated mining

为研究近距离煤层群下行开采工作面煤体破坏特征和矿压显现规律,本文采用PHASE 2D有限元分析软件建立数值模型,研究了杨家寨煤矿近距离煤层下行开采重复采动影响下工作面煤壁破坏特征、围岩应力分布规律及覆岩移动演化特征。数值模拟结果显示:①工作面煤壁在顶底板挤压作用下外鼓,下煤层较上煤层的煤壁破坏更为明显,上、下煤层工作面最大塑性区宽度分别为2.43 m和3.18 m;②随着工作面的推进,工作面支承压力增高系数峰值先增大后稳定,上煤层支承压力增高系数稳定在1.60左右,而下煤层支承压力增高系数稳定在1.52左右;③上、下煤层工作面各推进200 m时,覆岩最大位移分别为36 mm和73 mm,但上煤层工作面达到了充分采动,覆岩最大位移不再增大,而下煤层工作面仍处于非充分采动阶段,覆岩最大位移将随工作面的推进继续增大。

In order to study the failure characteristics of coal body and the law of mine pressure appearance in the downward mining face of close distance coal seam group,PHASE 2D finite element analysis software was used to establish a numerical model to study the failure characteristics of coal wall,the stress distribution law of surrounding rock and the evolution characteristics of overburden movement under the influence of repeated mining in the downward mining of close distance coal seam group.The numerical simulation results showed that:①The coal wall of the working face bulges under the extrusion of the roof and floor,and the coal wall damage of the lower coal seam was more obvious than that of the upper coal seam.With the advance of the working face,the peak value of the abutment pressure increase coefficient of the working face increases first and then stabilized.The abutment pressure increase coefficient of the upper coal seam was stable at about 1.60,while that of the lower coal seam was stable at about 1.52.When the working faces of the upper and lower coal seams advanced 200 m respectively,the maximum displacement of the overlying strata was 36 mm and 73 mm respectively,but the working face of the upper coal seam reached full mining,and the maximum displacement of the overlying strata no longer increased,while the working face of the lower coal seam was still in the stage of insufficient mining,and the maximum displacement of the overlying strata would continue to increase with the advancement of the working face.