In the process of coal mining, the surface subsidence under ultrathick loose layer is abnormal (subsidence coefficient greater than 1.0), which will cause great damage to the surface ecological environment. The fracture propagation and stress evolution of bedrock are of great significance to the prevention of surface subsidence. Taking the 1305 working face of a mine as the background, this paper study the process of crack propagation and stress evolution of bedrock under the influence of ultrathick loose layer by methods of on-site measurement, similar simulation, and numerical simulation. During the research process, the physical model was verified by the measured data. Then, the numerical model was verified by the crack propagation angle and subsidence of bedrock, which were obtained in a similar simulation. Based on the verified numerical model, it was obtained that after the coal seam was mined out, the bedrock above the mined-out area was mainly damaged by tension, while the strata on both sides of the crack expansion angle were mainly damaged by shear and tension. During coal seam mining, for bedrock the process of fracture expansion, subsidence, and stress evolution all could be divided into four stages. This research provides a basis for the control of surface subsidence.

中文翻译：

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超厚疏松层下采煤沉陷规律数值模拟试验研究

在采煤过程中，超厚疏松层下的地面沉降是异常的（沉降系数大于1.0），这将对地表生态环境造成很大的破坏。基岩的裂缝扩展和应力演化对防止地表沉陷具有重要意义。以矿山1305工作面为背景，通过现场测量，相似模拟和数值模拟的方法研究了超厚疏松层影响下基岩的裂纹扩展和应力演化过程。在研究过程中，通过测量数据验证了物理模型。然后，通过在类似模拟中获得的裂纹扩展角和基岩的沉降来验证数值模型。根据验证的数值模型，可以得出，采煤后，采空区上方的基岩主要受拉力破坏，而裂纹扩展角两侧的地层主要受剪切力和破坏力的影响。紧张。在煤层开采过程中，对于基岩而言，裂缝扩展，沉降和应力演化过程都可以分为四个阶段。该研究为控制地面沉降提供了依据。