综放开采顶煤采出率预测模型的构建与应用

顶煤采出率是厚煤层综放开采最为关注的的核心问题之一,为了明确放煤终止原则,最大程度地提高顶煤采出率,基于随机介质流理论,首先推导了煤矸分界线和放出体方程,根据放出体方程分析了顶煤放出体的形态演化特征。协同考虑煤矸分界线和顶煤放出体的形态演化,建立了顶煤采出率与含矸率的理论计算模型,并根据此模型探讨了不同顶煤厚度条件下顶煤采出率与含矸率的相互关系;然后结合塔山煤矿生产实际,利用模型试验设置了两种顶煤厚度,获得了顶煤采出率与含矸率的试验关系曲线;最后对塔山煤矿8101,8102和8111三个工作面顶煤采出率与含矸率进行现场实测,并根据实测数据拟合出顶煤采出率与含矸率的关系曲线;将模型试验和现场实测所得顶煤采出率与含矸率关系曲线分别与理论研究对比分析,验证了理论分析的可行性。研究结果表明:顶煤放出过程中,放出体轴偏角随放出体高度增加逐渐减小,即放出体逐渐向煤壁方向倾斜,其形状由尾梁切割类圆形逐渐过渡为类椭圆形;针对某一固定采高和放出体高度,顶煤越薄,对应的放出体轴偏角及放出量越大;顶煤采出率与含矸率呈非线性增大关系,提出了顶煤拐点采出率与拐点含矸率概念,生产实际中,可将含矸率9%～16%作为厚煤层综放开采放煤终止的参考依据。

A model for top coal recovery ratio assessment and its application in longwall top coal caving

Top coal recovery ratio is one of the core issues in longwall top coal caving (LTCC) mining. In order to clarify the criterion for stopping the caving and maximizing the top coal ratio,the equations of the top coal boundary and drawing body were derived based on the stochastic medium theory,and using the drawing body equation,the evolution characteristics of drawing body was analyzed. Considering the top coal boundary and drawing body,the theoretical model for calculating the top coal recovery ratio and rock-mixed ratio was established,which was used to model the interrelationship between the top coal recovery ratio and rock-mixed ratio under different top coal thicknesses. Then,combined with the production practice in Tashan mine in China,two model experiments with different top coal thicknesses were carried out to obtain the relation curve on the top coal recovery ratio and rock-mixed ratio. Finally,aimed at the working faces 8101,8102 and 8111 in Tashan Mine,the field observation on the top coal recovery ratio and rock-mixed ratio was conducted,and the relation curve on the top coal recovery ratio and rock-mixed ratio was obtained based on the measured data. To prove the theoretical analysis,the relation curves from the model experiment and field observation were analyzed and compared to the theoretical curve,respectively. The results show that during the top coal drawing process,the deflection angle of drawing body decreases with the increase of drawing body height, i. e. the top coal drawing body gradually inclines toward the coal wall,and the shape of drawing body gradually turns into a cut variant ellipsoid from an unrepresentative round. For the fixed cutting height and drawing body height,the deflection angle and the drawing volume are bigger when the thickness of top coal seam is small than that when the thickness of top coal seam is large. top coal recovery ratio increases nonlinearly with the increasd of rock-mixed ratio. The concepts of top coal inflexion recovery ratio and inflexion rock-mixed ratio were presented,and the rock-mixed ratio 9% -16% can be used as the criterion for stopping caving in practical LTCC mining.