School of Mines, China University of Mining & Technology
State Key Laboratory of Coal Exploration and Intelligent Mining, China University of Mining & Technology
School of Computer Science and Technology, China University of Mining and Technology
Inner Mongolia Haosheng Coal Industry Co., Ltd.

鄂尔多斯矿区侏罗系煤层覆岩中常见巨厚层状砂岩组，为了解释和量化巨厚覆岩下煤层开采矿震破裂机制与顶板破断特征，基于震动波P波辐射位移场与相对矩张量反演方法，提出了以震源群为单位、微震台站为对象构建反演矩阵进行煤矿矿震震源机制反演，提高了反演效率与准确性，求解了巨厚覆岩下实体煤段与临空段工作面回采诱发大能量矿震事件的震源机制，定量分析了顶板破裂演化特征与震动波辐射影响方位。结果表明：巨厚覆岩下临空段工作面回采白垩系巨厚砂岩层开始产生破断，地表沉降量快速上升，开始出现100 kJ以上的矿震事件，矿震分布较实体煤阶段更为密集；大部分大能量矿震事件位于采空区后方，与煤层上方厚层顶板破断、滑移密切相关；巨厚覆岩下煤层开采诱发的震源顶板张拉破裂占比85%以上，临空段回采期间震源有向上扩展的趋势，剪切滑移破裂相对实体煤回采阶段有所增加；破裂面走向方向大致与工作面推进方向一致或与工作面推进方向成“X”夹角，但临空回采阶段相较实体煤阶段走向“X”夹角由30°增加至45°；震源破裂面倾角0°～30°，占比50%左右，顶板以水平离层张拉、顶板回转压缩失稳为主，产生的P波大多向下方采空区传播，对工作面回采影响较小；仅部分顶板断裂张拉与剪切滑移失稳产生的P波向周围采场传递，可能对工作面影响较大。巨厚覆岩型矿震的防治思路可从弱化巨厚覆岩的整体性、使巨厚覆岩结构分层破断的角度出发，降低巨厚覆岩整体破断诱发矿震对工作面冲击危险性的影响。

In the Ordos mining area of North China, the Jurassic coal seam is commonly overlain by extremely thick cretaceous sandstone strata. Based on the seismic displacement field and relative moment tensor inversion method, this paper investigates the mine earthquake mechanism and roof fracture characteristics of coal seams under extremely thick strata. In this study, by using seismic source groups as units and microseismic stations as objects, the source mechanism of mine earthquakes is inverted by constructing an inversion matrix, which greatly improves the inversion efficiency and accuracy. The focal mechanism of large-energy mine earthquakes located in solid coal section and goaf section under extremely thick strata is calculated. The characteristics of roof fracture evolution and the influence of vibration wave radiation are quantitatively analyzed. The results show that the extremely thick strata of Cretaceous goaf start to break when the panel below retreats along goaf. During this period, the surface subsidence increases rapidly, and the significant mine earthquakes with energy above 100 kJ begin to occur, and the mine earthquake distribution is more concentrative than that in the solid coal stage. Most of the large-energy mine earthquakes are located behind the goaf, which is closely related to the breakage and slide of the thick roof. Roof tension rupture accounts for more than 85% of the mine earthquakes. During mining along goaf, the seismic sources tend to expand upward, and more shear slip ruptures are presented compared with that in the solid coal mining stage. The strike of the fracture surface has a similar direction or an angle of “X” with the advancing direction. However, compared with that in the solid coal stage, the angle of “X” during mining along goaf increases from 30° to 45°. For the source rupture surface, the dip angle of between 0°−30° accounts for about 50% of the total. The failure type of roof is dominated by horizontal separation tension and roof rotation compression. The generated P waves mostly propagate to the goaf below, which causes a minor influence on the mining face. Only a small part of the P waves propagate to the surrounding working face, which may pose a great impact on the working face. The prevention and control strategy on the extremely-thick-strata type mine earthquakes can be conducted by weakening the integrity of thick strata and making thick strata break in tiers, aiming to reduce the rockburst risks to the working face induced by the breakage of the whole thick strata.

国家自然科学基金资助项目(52274098，U21A20110)；国家重点研发计划资助项目(2022YFC3004603)

白贤栖，曹安业，刘耀琪，等. 基于震源机制解析的巨厚覆岩矿震破裂机制[J]. 煤炭学报，2023，48(11)：4024−4035.

BAI Xianxi，CAO Anye，LIU Yaoqi，et al. Mine earthquake mechanism of extremely thick strata based on focalmemchanism analysis[J]. Journal of China Coal Society，2023，48(11)：4024−4035.