The orthogonal experiments of similar materials were optimized and analyzed in order to accurately simulate the mechanical properties and the fracture evolution law of thick coal seam overlying strata during mining in this study. The experimental results indicated that similar materials using gypsum and calcium carbonate as cementing agents had a wide range of compressive strength (173.80 kPa–425.95 kPa) and were suitable for simulating various rock properties. Adding an appropriate amount of calcium carbonate can improve the brittleness and mechanical properties of similar materials using gypsum as cementing agents. The failure mode of similar materials transitioned from shear to tensile failure with the increase of the mass ratio of aggregate to cementing agents and the mass ratio of calcium carbonate to gypsum. Moreover, the compressive strength of similar materials rapidly decreased with an increase in the mass ratio of aggregate to cementing materials. And the compressive strength showed an increasing trend with the decrease of the mass ratio of calcium carbonate to gypsum. Moisture content had a significant impact on the density of similar materials, other parameters had small impacts. A thick coal seam mining experimental model was designed based on the experimental results of similar materials, which showed that Qianjiaying Mine may experience basic roof collapse when mining reached 58.1 m. The recommended periodic weighting pace for face pressure on the working face was approximately 15.0 m. Appropriate measures are necessary to adopt to prevent disasters after mining to a length of 58.1 m, followed by every 15.0 m of mining.

中文翻译：

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厚煤层开采同类材料试验研究及应用

为了准确模拟厚煤层覆岩开采过程中的力学性能和断裂演化规律，对同类材料的正交试验进行了优化和分析。实验结果表明，以石膏和碳酸钙为胶结剂的同类材料具有较宽的抗压强度范围（173.80 kPa~425.95 kPa），适合模拟各种岩石性质。添加适量的碳酸钙可以改善以石膏为胶结剂的类似材料的脆性和力学性能。随着骨料与胶结剂质量比、碳酸钙与石膏质量比的增大，同类材料的破坏模式由剪切破坏转变为拉伸破坏。而且，随着骨料与胶凝材料质量比的增加，同类材料的抗压强度迅速下降。并且随着碳酸钙与石膏质量比的减小，抗压强度呈现增加趋势。含水量对同类材料的密度影响较大，其他参数影响较小。根据同类材料的试验结果，设计了厚煤层开采试验模型，表明钱家营矿在开采深度达到58.1 m时可能出现基本顶板塌陷。工作面工作面压力的建议定期称重步长约为 15.0 m。开采至58.1m后，应采取适当的防灾措施，每开采15.0m后，应采取适当的防灾措施。