煤层小褶曲附近采动应力演化特征与瓦斯突出防治

为提高煤层小褶曲构造附近瓦斯突出灾害防治的针对性,以古汉山矿地质条件为背景,通过FLAC3D数值模拟方法开展了小褶曲附近采动应力场演化特征及对瓦斯灾害的影响规律研究。结果表明:工作面从背斜端或从向斜端揭露小褶曲过程中,小褶曲附近应力场大小呈现逐渐增大的变化特征,在揭露褶曲前应力增大至峰值状态;在揭露褶曲时刻,处于峰值状态的应力迅速降低,释放出大量的弹性能,迫使煤体产生剧烈位移,容易诱发瓦斯突出动力灾害。小褶曲附近高应力积累部位对现场瓦斯突出防治工作至关重要,可以在加强小褶曲探测的基础上,结合区域地应力场方向、构造产状特征、开采条件对煤层瓦斯突出的危险部位及发生时刻做出预测,从而制定出针对性的瓦斯突出防治措施。

Evolution characteristics of the mininginduced stress near the small-scale folds in the coal seam and the gas outburst prevention

The paper is aimed to investigate the evolutionary characteristic features of the mining-induced stress and its influence on the coal and gas mining near the small-scale folds in the process of the working face advancing in the coal seams. For the said purpose,we have built up the Mohr-Coulomb model of the working face with small-scale folds via the FLAC3D software in hoping to find a way on how to prevent such outburst hazards near the small-scale folds effectively based on the background of Guhanshan coal mine geological conditions. The results of our investigation show that the stress field near the fold areas has been increasing gradually while the working face is advancing to it from the syncline edge or the anticline edge of the small-scale folds, and then the stress in existence can likely grow and reach the maximum limit beyond the control sphere to the outburst of the original small-scale folds. Moreover,with the time advancing, there would occur a rapid decrease of high stress in the front of the working face at the moment when the fold is being disclosed. And,simultaneously,obvious declining trend of the elastic energy would appear,which may force and cause severe displacements in the coal seam body. Thus,as a result of the severe displacements in the coal seam and the elastic energy declining,disasters would inevitably come about to the unstable state in the coal body,as well the coal and gas outburst disasters. Furthermore, the high stress accumulation sites near the small-scale folds tend to harm and be unfavorable for preventing the coal and gas outbursts. Therefore,based on the detection of the small-scale fold deformation in the coal seams,it is necessary to trace the status-in-situ stress field,and take the mining conditions and folds strikes into full account to observe and forecast the high stress concentration area near the small folds in the process of the working face advancing,so as to enhance the pertinence work of the gas outburst prevention and control near such areas.