巨厚坚硬顶板下半孤岛采场微震响应特征研究

Microseismic response characteristics of semi-island working face under extra-thick hard roof

巨厚坚硬顶板下半孤岛工作面回采过程中顶板易产生强动载,矿压显现剧烈,巷道支护困难,冲击危险性高,针对滕县煤田具体的工程地质条件,利用SOS微震技术对某矿保护层下3_(下)1103工作面回采过程中顶底板运动规律监测,以期为该类工作面的防冲工作增添依据。结果表明:该条件下煤层顶板完整性差,岩块回转、下沉等结构性演化是顶板震动的主要来源,重复采动下高位顶板多在末采期间破断,并释放大量能量,危害较大;煤层底板破坏是主要的能量释放途径,构造和煤柱附近底煤冲击危险增大;微震事件频次或能量的降低能够预测强动载出现的时机;大面积采空和半孤岛结构导致S型覆岩空间结构向孤岛侧偏移,实体煤巷道冲击危险性增加。

During the mining of semi-island working face with extra-thick hard roof, the roof is prone to produce strong dynamic load, leading to intense strata pressure, difficult roadway support, and high risk of rockburst. According to the engineering geological conditions of Tengxian coalfield, the SOS microseismic technology was used to monitor the movement of roof and floor during the mining of the 1103 working face under the protective seam of a certain mine. The results showed that, the integrity of coal seam roof was poor, and the structural evolution of rock block rotation and subsidence was the main source of roof vibration. Under repeated mining, the high roof was mostly broken during the end mining, and a large amount of energy was released, which was of great harm. The failure of coal seam floor was the main energy release way, and the rockburst risk of bottom coal near the structure and coal pillar increased. The decrease of microseismic event frequency or energy could be used predict the occurrence time of strong dynamic load;large mined-out area and semi-island structure led to S-type rock spatial structure shift to island side, which increased the rockburst risk of solid coal roadway.