考虑煤矸嵌锁效应的水平分段综放开采合理分段高度确定

Determination of reasonable sublevel height in sublevel top coal caving mining considering the embed-lock effect of coal and gangue

  • 摘要: 针对急倾斜特厚煤层水平分段综放开采中顶煤放出规律复杂、合理分段高度难以确定的工程难题,采用散体动力学理论、离散元数值模拟、物理试验与深度学习算法相结合的方法,揭示了放煤过程中煤矸块体间嵌锁效应主导的“松动—压实”循环机制,构建多参数数值模拟方案,开展物理试验验证,并建立基于序列数据的回收率及合理分段高度预测模型。本文探究了分段高度、工作面长度、煤层倾角对嵌锁效应及顶煤回收率的影响规律,发现煤层倾角和分段高度越大,嵌锁效应越明显,不利于顶煤的顺利放出,而工作面长度对嵌锁效应的影响不大,较小的分段高度有利于减弱嵌锁效应、促进顶煤的顺利放出。工作面长度越小、分段高度越高,工作面中部的放煤量更加均匀;煤层倾角越大、分段高度越高,靠近工作面顶板侧的放煤口放煤量逐渐增加。工作面长度越大,煤层倾角越小时,采用较小分段高度可以有效减少顶煤成拱、提高工作面的回收率,而当煤层倾角大于70°时,应选取较大分段高度可以削弱嵌锁效应、提升顶煤回收率。构建LSTM+Transformer的回收率及合理分段高度预测模型,实现回收率与合理分段高度的准确预测(R2=0.9469)。研究为乌东煤矿等水平分段综放工作面提供了分段高度的动态优化方法,有助于实现急倾斜煤层的高回收率开采。

     

    Abstract: In response to the engineering challenges of complex top coal drawing laws and difficulties in determining a reasonable sublevel height during sublevel top coal caving mining of steeply inclined extra-thick coal seams, an integrated approach combining granular dynamics theory, discrete element numerical simulation, physical experiments, and deep learning algorithms was employed. This study revealed the "loosening-compaction" cycle mechanism dominated by the interlocking effect between top coal blocks in top coal caving mining. A multi-parameter numerical simulation scheme was developed, physical experiments were conducted for validation, and a prediction model for recovery rate and reasonable sublevel height based on sequence data was established. The influence patterns of sublevel height, face length, and coal seam dip angle on the interlocking effect and top coal recovery rate were investigated in this paper. Results indicate that a larger coal seam dip angle and greater sublevel height lead to a more pronounced interlocking effect, which is detrimental to the smooth drawing of top coal. In contrast, the face length has little influence on the interlocking effect. A smaller sublevel height helps weaken the interlocking effect and promotes smooth top coal drawing. A smaller face length coupled with a higher sublevel height results in more uniform coal drawing between the middle sections of the face. A larger dip angle and higher sublevel height cause a gradual increase in the amount of coal drawn from the openings near the roof side of the face. When the face length is larger and the coal seam dip angle is smaller, adopting a smaller sublevel height can effectively reduce top coal arching and improve the recovery rate of top coal. However, when the coal seam dip angle exceeds 70°, selecting a larger sublevel height can mitigate the interlocking effect and enhance the top coal recovery rate. A prediction model combining LSTM and Transformer was constructed for recovery rate and reasonable sublevel height, achieving accurate predictions (R2= 0.946 9). This research provides a dynamic optimization method for sublevel height in sublevel top coal caving faces, such as those in the Wudong Coal Mine, contributing to the high recovery rate mining of steeply inclined coal seams.

     

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