Abstract With the development of mining depth, multi-seam mining activities is becoming more and more frequent. Correspondingly, the study on stratum movement characteristics induced by multi-seam mining activities is of great significance for preventing water inrush disaster and forecasting support pressure, surface deformation, gas drainage and other mining problems. According to the interaction among the caved zone, the fractured zone and the continuous deformed zone caused by the multi-seam downward mining activities, multi-seam can be divided into three types, i.e. the short-distance, middle-distance and long-distance multi-seam. This paper carries out a case study on the middle-distance multi-seam mining activities in a coal mine in China to investigate the characteristics of stratum movement caused by downward longwall coal mining activities in the multi-seam by means of borehole water level observation, digital borehole camera test, microseismic monitoring, surface crack observation of the surface cracks and distinct element modelling. By analyzing the in-site monitoring results and the numerical simulation results, it can be found that the failure of the key stratum between the lower and upper seams resulting in the connection between the failed zone in floor induced by the upper seam and the fractured zone induced by the lower seam. After the failure of the key stratum, the mining activities of the lower seam has a great influence on the secondary stratum movement in the overburden. These effects are mainly reflected in the rapid increase of horizontal displacement and vertical displacement, which caused the caved and fractured zones extend upward in the overburden and then surface cracks increase significantly. The above research results are of great significance for the prevention and control of disasters induced by downward longwall mining activities in middle-distance multi-seam.

中文翻译：

---

中距离多煤层下长壁开采活动诱发地层运动特征

摘要 随着开采深度的发展，多煤层开采活动越来越频繁。相应地，研究多煤层开采活动引起的地层运动特征，对于防治突水灾害和预测支护压力、地表变形、瓦斯抽采等开采问题具有重要意义。根据多煤层向下开采活动引起的塌陷带、裂缝带和连续变形带之间的相互作用，多煤层可分为短距离、中距离和长距离三种类型。多缝。本文以我国某煤矿中距离多煤层开采活动为例，通过钻孔水位观测，研究多煤层下长壁煤矿开采活动引起的地层运动特征，数字钻孔摄像机测试、微地震监测、地表裂纹的表面裂纹观察和独特的元素建模。通过对现场监测结果和数值模拟结果的分析，可以发现上下煤层之间关键地层的破坏导致上层煤层诱发的底板破坏带与裂缝带的连接。由较低的接缝引起。关键层失败后，下层煤层的开采活动对上覆地层次生地层运动有很大影响。这些影响主要体现在水平位移和垂向位移的快速增加，导致上覆岩层中的塌陷带和裂缝带向上延伸，地表裂缝显着增加。上述研究成果对中距离多煤层下长壁开采活动灾害的防治具有重要意义。