煤与瓦斯突出过程中气压时空演化规律

Temporospatial evolution of gas pressure during coal and gas outburst

煤与瓦斯突出是严重威胁煤矿安全生产的地质灾害之一。近年来,随着采掘深度不断增加,地应力与瓦斯压力不断加大,突出次数也日益频繁,同时由于煤矿井下开采活动,使煤岩体中地应力场发生变化,在掘进工作面或回采工作面前方形成由卸压区、应力集中区和原始应力区组成的三带,给煤与瓦斯突出的预防与治理带来更大的困难。以天府三汇一矿为工程背景,基于相似理论试验模拟了采动条件下的煤与瓦斯突出过程,并分析了突出过程中气压的时空演化规律。研究结果表明:突出的发展是煤体由突出启动点向周围逐渐破坏并抛出的过程,相对突出强度为8.79%,且突出过程具有阵发性,表现为煤体的间歇式多次抛出和气压的反复升降,其中突出口附近气压的升幅较大,达到69.2%,而远离突出口处气压表现为短时间内急剧下降,之后缓慢下降并逐渐趋于大气压;突出过程中气压等压面近似以突出口为中心呈球面分布,且气体解吸区域近似呈球壳状逐渐向外扩展,球壳的扩展速度约为130 mm/s,球壳附近气压梯度较大。

Coal and gas outburst is one of the most serious disasters in coal mining. In recent years, with the increasing of mining depth, the in-situ stress and gas pressure increase, and thus the coal and gas Outbursts occur more and more frequently. At the same time, the in-situ stress in coal changes with mining activities; the ＂three zones＂ are formed, i.e, stress relaxation zone, stress concentration zone and original stress zone in the areas in front of the heading face and the working face, which brings more difficulties to the prevention and control of coal and gas outburst. Tianfu Sanhui No.1 mine is selected as an analysis example. The process of gas outburst is physically simulated according to the similarity theory, and the temporospatial evolution of gas pressure is discussed. It is shown that the development of outburst is a process of coal breakage in the cavity wall, which starts from the start part to the surrounding, with a relative intensity of 8.79%. Pulverized coals are thrown out intermittently and the gas pressure rise up and down in many times. The gas pressure close to the outburst mouth has a large change up to 69.2%, while it declines sharply with a short period at first then fall slowly to the atmospheric pressure far away from the outburst mouth. The isobaric surface distributes at the spherical center of outburst mouth during outburst. The gas desorption area expands outward with the shape＇of spherical shell and the expansion speed of spherical shell is about 130 ram/s, and the gas gradient nearby is greater.