变宽度孤岛工作面回采期间冲击危险性数值评估研究

Study on numerical assessment of rock burst risk during the recovery of variable width island working face

对采掘工作面进行冲击危险性评价是开展冲击地压防治的首要步骤。针对综合指数法对大量特殊地质和开采条件工作面难以适用的困境,本文以山西省杜儿坪煤矿变宽度孤岛工作面为对象,开展了基于有限差分数值计算方法的特殊开采条件工作面回采期间的冲击危险性评价研究。研究根据矿井实际煤岩赋存条件建立了工作面大尺度三维模型,先后计算了工作面准备阶段、两侧采空阶段、孤岛工作面回采阶段等三个阶段工作面围岩冲击危险区分布范围和危险程度,进而确定了变宽度孤岛工作面回采期间的冲击危险区段。研究结果表明,杜儿坪煤矿变宽度孤岛工作面回采过程中主要冲击危险性影响因素为冲击地压为工作面几何尺寸的突变和孤岛工作面临空条件的突变,该因素导致了回采过程中的两个主要冲击危险区段,分别为工作面变宽度区段和末采区段,对工作面在该区段的回采作业发出了冲击危险性预测和防冲措施建议,最终保证了工作面的安全回采。研究证明了有限差分数值计算方法对于特殊开采条件工作面冲击危险性评价的可行性,可作为综合指数法的互补方法。

Assessment of rock burst risk for excavating work places in underground is the first step for rock burst control.Combined indexing method has been proved not suitable for quantity of work places with abnormal geological or mining conditions.Focusing on solving this dilemma,the present research adopted numerical methods to proceed the evaluation of rock burst risk for variable width island working face based on Du’erping Coal Mine located in Shanxi Province.This paper establishes a large-scale three-dimensional model of the working face based on the actual coal and rock conditions in the mine.It successively calculates the distribution range and degree of risk of the surrounding rock impact danger zone in three stages:the preparation stage of the working face,the two sides goaf stages,and the mining stage of the island working face,and then determines the impact risk section during the mining of the variable width island working face.The results show that the change in dimension and neighboring condition are the main factors contributing to the burst risk variation.Two main impact risk sections will appear during the mining process of this variable width island working face of Du’erping Coal Mine respectively,the variable width section of the working face and the final mining section.The impact risk prediction and anti-impact measures are proposed for the mining operation in these sections,ultimately ensuring the safe mining of the working face.The present study proves that the numerical method’s potential to evaluate burst risk for panels with special mining conditions and the feasibility to serve as supplemental method for combined indexing method.