复合煤层群双重卸压应力时空演化规律研究
Study on Space-time Evolution of Stress Under Double Pressure Relief in Composite Coal Seam Group
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摘要: 为探索复合煤层群保护层开采过程中，在双重卸压条件下首采保护层和次采保护层过程中卸压特征的不同，采用相似材料实验、计算机数值模拟研究双重卸压覆岩裂隙发育、变形特征和应力分布时空演化规律，通过对比分析表明：在二次保护层开采条件下，覆岩部分裂隙经历了二次扩张，压实，吻合，部分裂隙在空间上往深部发育，裂隙带高度范围增加。应力在首采保护层应力状态的影响下进行再分布，随开采过程形成了5个应力分布区域，分别为工作面超前应力集中区、卸压区、压实区、采空区后方应力集中区、原岩应力区。双重卸压下采空区两端卸压效果更为显著，超前应力集中系数较首采保护层要高，采空区压实速度较首采保护层快，同时被保护层卸压程度和范围均显著增加。Abstract: To explore different characteristics of pressure relief in the protective layer mining process of composite coal seam group, under the condition of double pressure-relief mining of closed distance coal seams group, we study the strata fracture development characteristics and stress distribution with time and space evolution. Through the similar material experiment and computer numerical simulation, the results show that the double pressure-relief mining results in complicate process of some of the overlying rock fracture, such as second expansion, compaction and match. Part of the crack develops to the deep in the space, and the fracture zone height increases in the vertical. The stress achieves redistribution under the influence of initial mining protective layer, and forms five stress area in the mining process, the effect is more significant on both ends of the mined-out area under the condition of double pressure-relief, the stress concentration factor is relatively higher to initial mining protective layer; compaction speed is faster than initial mining protective layer of mined-out area; unloading degree and range of protected layer are significantly increased.
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Keywords:
- protective layer /
- stress /
- crack /
- double pressure relief /
- coal seam group /
- space-time evolution
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