School of Civil Engineering, North China University of Technology

为了研究近距离煤层群上行开采对工作面围岩应力分布规律及覆岩破坏演化特征的影响,采用PHASE2D有限元软件建立数值模型,分析了近距离煤层群上行开采过程中工作面煤壁塑性区发展规律、覆岩垂直位移、工作面前方支承应力分布规律。数值模拟结果显示,工作面煤壁塑性区呈现上部宽、下部窄的特征,随着工作面不断推进,煤壁塑性区宽度也随之增大,其中下层煤和上层煤工作面煤壁塑性区最大宽度分别为4.23m、2.85m;下层煤和上层煤覆岩最大竖向位移都发生在模型中部,最大竖向位移分别为28mm、62mm;支承压力呈现出先增大再减小、最后趋于稳定的发展趋势,支承压力系数峰值为1.59。研究结果表明,在上行开采实践中,当下层煤完成开采后,上层煤的围岩塑性区和位移均有所增大,覆岩稳定性降低。

In order to study the stress distribution of the surrounding rock and the evolution characteristics of the overlyingrock failure caused by the upward-mining of the close coal seams group, we apply the PHASE 2D finite element software toestablishing a numerical model, and analyze the development of coal face plastic zones, the vertical displacement of the overlying strata at different advancing distances, and the distribution of the bearing pressure in front of the working face. The numerical simulation results show that: The plastic zones of the coal wall are wider at the top position and narrower at the bottom. With the continuous advance of the working face, the width of the plastic zones also increases, and the maximum widthof the plastic zones for the lower and upper coal working faces are 4. 23 m and 2. 85 m, respectively; The maximum verticaldisplacement of the overlying strata appears in the middle of the model, and the maximum vertical displacement after thecompletion of the lower and the upper coal seams are 28 mm and 62 mm, respectively; The bearing pressure increases to itspeak and then decreases and stabilizes. The peak bearing pressure coefficient is 1. 59. Our study indicates that: After thecompletion of the lower coal seam, the plastic zones in the face area and the displacement of the surrounding rocks for theupper seam are larger, while the stability of the overlying strata decreases.