Tiandi Science and Technology Co. , Ltd.
CCTEG Coal Mining Research Institute

针对马道头煤矿坚硬顶板特厚煤层综放开采顶煤回收率低的问题,采用理论分析、数值模拟、现场试验等方法,分析了顶板结构与顶煤受力状态的对应关系,揭示了顶煤空间破坏特征,评价了地面压裂双效弱化技术应用效果,结果表明:顶板结构根据顶煤受力状态将分为“组合短悬臂梁”+“铰接岩梁”混合承载结构、“组合短悬臂梁”单独承载结构、“铰接岩梁”单独承载结构,采取措施后,覆岩结构稳定性变差,覆岩破坏高度增大,厚层砂岩悬顶消失,超前支承压力峰值明显降低,顶煤完整性遭到破坏,弱化措施可以有效降低工作面回采期间厚层坚硬顶板引起的悬顶长度、应力集中程度及顶煤完整性,压裂影响区内,非来压期间,循环末阻力下降25.4%,来压期间循环末阻力下降15.3%,地面压裂后覆岩分层破坏程度较高,坚硬厚层岩层薄层化,顶煤回收率得到了提高,比未经地面压裂弱化顶煤时回收率增加了6.1%。

In view of the low top coal recovery rate in fully mechanized top coal caving mining of extra thick coal seams with hard roof, taking the fully mechanized top coal caving mining of “two hard” coal seams as the actual field conditions, theoretical analysis, numerical simulation, field tests and other methods are used to analyze the corresponding relationship between roof structure and top coal stress state, to reveal the top coal space damage characteristics, and evaluate the application effect of surface fracturing double effect weakening technology. The results show that the roof structure can be divided into “combined short cantilever beam” + “articulated rock beam” hybrid bearing structure, “combined short cantilever beam” independent bearing structure, and “articulated rock beam” independent bearing structure according to the stress state of the top coal. After implementing fracturing measures, the stability of the overburden structural stability worsens, the failure height of the overburden increases, the thick sandstone overhang disappears, the peak value of the advance bearing pressure decreases significantly, and the integrity of the top coal is damaged, weakening measures can effectively reduce the suspended length, stress concentration, and integrity of the top coal caused by the thick and hard roof during the mining process of the working face. Within the range of fracturing damage area, the end of cycle resistance decreases by 25. 4% during non pressure periods, and the cycle resistance decreases by 15. 3% during pressure periods. After surface fracturing, the degree of damage to the overlying rock layers is relatively high, and the hard and thick rock layers become thin layers, resulting in an improvement in the recovery rate of the top coal, the recovery rate of the top coal increased by 6. 1% compared to the top coal weakened without surface fracturing.

薛吉胜. “两硬”煤层条件下综放开采煤岩全区双效弱化技术研究 [J]. 煤炭工程, 2023, 55(12): 5-10.