Cunhan Huang, Lili Shen, Cao Zhengzheng, Feng Du, Zhenhua Li, Yongqiang Yu
School of Resources and Environment, Henan Polytechnic University, Jiaozuo, 454000, Henan, China.
International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention, School of Civil Engineering, Henan Polytechnic University, Jiaozuo, 454000, Henan, China.
Sci Rep. 2025 Mar 24;15(1):10065. doi: 10.1038/s41598-024-77324-7.
With the increase of coal seam mining intensity in the western mining area, which has the typical mining geological characteristics of shallow burial depth, thin bedrock and thick loose layer, the structure of overburden rock has also changed greatly. When there is only one key layer structure in the thick bedrock and it is close to the coal seam, the strata pressure and surface crack development law of the working face are different from those of previous research results. Based on the research background of 52,307 large mining height working face in Daliuta Coal Mine, this paper adopts similar simulation and numerical simulation techniques to systematically study the strata pressure and surface crack development laws of the working face under the roof condition of such main key layer. The results show that: There is only one key layer in the roof overburden of the working face and it is only about 4 m away from the coal seam, and the key layer is broken in layering during the mining process, the lower part of the key layer collapses by itself under the influence of mining and falls into the collapse zone, and the upper part of the key layer forms a "face contact block" structure, which was unstable and broke to form a "surface contact block arch" structure, and caused the periodic pressure of the working face. The fracture and migration of key layers affects the movement of the overlying rock layers. When the key layer is broken and unstable, the overburden rock moves as a whole, forming a tensile effect on the surface and producing surface cracks. When the key layer of the working face is broken by the "fixed support beam" for the first time, ground cracks appear on the surface in a short time, and the surface cracks have a certain hysteresis, but the lag distance is short. In the process of pressure in each cycle, with the fracture and instability of the key layer, the overlying rock layer sinks and deforms, and different forms of surface cracks occur in the surface soil layer due to the increase of tensile stress and horizontal deformation force, and the cracks generally lag behind the working face.
随着西部矿区煤层开采强度的增加，该矿区具有浅埋深、薄基岩、厚松散层等典型的开采地质特征，覆岩结构也发生了很大变化。当厚基岩中只有一层关键层结构且靠近煤层时，工作面的矿压及地表裂隙发育规律与以往研究成果不同。基于大柳塔煤矿52307大采高工作面的研究背景，本文采用相似模拟和数值模拟技术，系统研究了该主关键层顶板条件下工作面的矿压及地表裂隙发育规律。研究结果表明：工作面顶板覆岩中只有一层关键层，且距煤层仅约4m，关键层在开采过程中分层断裂，关键层下部在采动影响下自行垮落进入垮落带，关键层上部形成“面接触块体”结构，该结构失稳后断裂形成“面接触块体拱”结构，引发工作面周期来压。关键层的断裂和移动影响上覆岩层的运动。当关键层断裂失稳时，上覆岩层整体移动，对地表形成拉伸作用并产生地表裂隙。当工作面关键层首次被“固定支撑梁”折断时，地表短时间内出现地面裂隙，地表裂隙具有一定滞后性，但滞后距离较短。在各周期来压过程中，随着关键层的断裂失稳，上覆岩层下沉变形，地表土层因拉应力和水平变形力增大出现不同形式的地表裂隙，裂隙一般滞后于工作面。
