急倾斜特厚煤层水平分层大采高充填膏体与煤体协调承载特性研究

Study on bearing characteristics of filling paste and coal in steeply inclined extra-thick coal seams with large mining height and horizontal stratification

为了研究窑街三矿特厚急倾斜煤层水平分层膏体充填工作面煤壁的稳定性,首先基于压杆稳定力学模型,给出最大临界力Fct计算公式,进一步导出临界应力σct与分层高度的关系曲线,并给出了挠曲方程计算公式;其次建立FLAC3D数值计算模型,通过垮落法与充填法对比分析工作面前方煤壁的支撑压力、煤壁塑性区范围以及水平位移量与推进距离的关系;最后模拟分析了随着采充平行作业的推进,不同分层高度与工作面煤壁前方的支撑压力、煤壁塑性区范围以及水平位移量的关系。结果表明,当分层高度为4,5,6 m时,煤壁分别在距离底板3.12,3.9,4.46 m位置处挠曲最大,煤壁最大位移量分别为19,24,27 mm,且煤壁发生失稳片帮的临界应力分别为6.6,4.4,2.6 MPa,根据窑街具体情况,当分层高度为5 m,膏体充填工作面前方煤壁的最大支撑应力为3 MPa,未超过临界应力,即便煤壁向采空区最大移动24 mm也不会在工作面推进过程中发生煤壁片帮,且理论分析与数值计算结果基本一致,对窑街三矿特厚急倾斜煤层水平分层膏体充填开采具有借鉴意义。

In order to study stability of coal wall in large mining height working face with horizontal slicing paste filling in steeply-inclined extra-thick coal seams in Yaojie No.3 mine,the maximum critical force Fct calculation formula was firstly given based on stable mechanical model of pressure bar.A corelation curve was then derived between critical stressσct and stratification height and a flexural calculation formula was subsequently obtained.Secondly,a Flac3D numerical calculation model was established to compare and analyze the support pressure,plastic zone range of coal wall,and the relationship between horizontal displacement and advance distance of coal wall in front of the working face through caving method and filling method.Finally,with the advance of parallel mining and filling operation,the relationships between different stratification heights and supporting pressure,the plastic zone of coal wall,and the horizontal displacement of coal wall were simulated.Results have shown that when the layer height is 4,5,6 m,and coal wall is 3.12,3.9,4.46 m respectively from the floor,the deflection reaches its highest value with the coal wall maximum displacement of 19,24,27 mm,respectively,and the critical stress for the instability of coal wall in was 6.6,4.4,2.6 MPa.According to field data,when stratification height is 5 m,the biggest stress of the paste filling mining face in front of the coal wall support is 3 MPa,which does not exceed the critical stress.Even if the maximum movement of the coal wall to the goaf is 24 mm,rib spalling will not occur in the coal during the advance of the working face,and the theoretical analysis is basically consistent with the numerical calculation results,which can provide reference for the horizontal stratified paste filling mining of steeply-inclined extra-thick coal seams in Yaojie No.3 mine.