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针对浅埋采场在开采活动中常出现矿压显现剧烈、顶板和地表台阶下沉等问题,以神东矿区为背景,采用3维物理模拟试验研究浅埋深薄基岩工作面覆岩活动规律。模型试验尺寸长×宽×高为1 050 mm×2 000 mm×1 130mm,几何相似比为1∶100,容重相似比为1∶1.67,时间相似比为1∶10,应力比为1∶1.67,监测模型地表位移变化和顶板位移变化规律。结果表明:浅埋薄基岩煤层开采过程中,上覆岩层只出现冒落带和裂隙带,煤层直接顶随采随冒,基本顶初次来压步距为40 m,周期来压步距为20 m;上覆岩层及松散层出现台阶下沉现象,裂缝贯通地表,切眼和停采线附近出现溃沙现象,地表形成塌陷坑;上覆岩层运动以垂直运动为主,随工作面向前推进,顶板位移增加;靠近煤柱的上覆岩层出现搭桥结构,靠近煤柱的上覆岩层位移变化量较小,而远离煤柱的测点上覆岩层位移变化量较大;地表位移变化和上覆岩层位移变化整体上具有正相关性,但地表位移变化幅度较小,具有滞后性,且受到溃沙现象的影响,切眼和停采线附近地表形成塌陷坑且地表位移变化量增大。
Aiming at the problems that the underground pressure appears frequently in the mining activities of the shallow burying stope, the roof and the sinking of the roof and so on. Taking the Shendong Mining Area as the background, the 3-D physical simulation test is used to study the law of the overlying strata movement in the shallow burial bedrock . The size, length, width and height of the model test are 1 050 mm × 2 000 mm × 1 130 mm. The geometrical similarity ratio is 1: 100, the bulk density similarity ratio is 1: 1.67, the time similarity ratio is 1:10 and the stress ratio is 1: 1.67 , Monitoring model changes in surface displacement and roof displacement changes. The results show that during the mining process of shallow-buried thin bedrock, only the caving zone and fracture zone appear in the overlying strata. The coal seam directly tops with the mining, the first step pressure step on the basic top is 40 m, 20 m. Overlying strata and loose layers show step-sinking phenomenon. Cracks penetrate the ground surface, and the phenomenon of sand collapse occurs near the cut and cut-off lines. Collapse pits are formed on the ground surface. The movement of the overlying strata is mainly vertical, And the displacements of the top plate increase. The overburden structure near the coal pillar has a bridging structure. The displacement of the overlying strata near the coal pillar is relatively small, while the displacement of the overlying strata at the measuring point away from the coal pillar is relatively large. The displacement of overlying strata has a positive correlation as a whole, but the variation of surface displacement is small and lagged. Due to the influence of sand-slump, the surface of the earth near the cut-and-cut line forms a collapse pit and the variation of surface displacement increases .