School of Civil Engineering, Liaoning Technical University
Liaoning Key Laboratory of Mine Subsidence Disaster Preventionand Control, Liaoning Technical University
School of Environment, Liaoning University
Hongy-ang No.3 Mine, Shenyang Coking Coal Company Limited

为构建煤矿小尺度区域微震波传播速度模型,提高矿井含采空区复杂地质结构内微震源定位精度。依据矿山采空区覆岩“三带”岩层变形、层面离层、层内断裂和裂隙发育以及岩体扩容等特征,构建圆弧层面波速模型,分区描述采空区覆岩波速结构。并提出采用考虑岩层变形特征的微震波绕射传播路径增量和基于时间平均方程的裂隙岩层波速折减进行波速模型修正。基于层状均匀介质假设和斯奈尔定律,推导微震波传播路径和走时计算公式,并计算各传播方向上的异向等效波速。基于到时理论定位原理,选择以实测到时差与理论走时差之差构建震源求解目标函数,采用模式搜索算法进行震源位置求解。形成了基于采空区覆岩异向波速模型的微震源定位方法。通过三维算例和煤矿地面微震监测定位应用,验证了所提方法的可行性与定位效果。研究表明:① 由于煤矿地质环境中采空区遍布和微震波经由采空区传播的必然性,针对煤矿含采空区复杂地层结构特征,建立相应的异向波速模型,是提高矿山环境下微震源定位精度的关键;② 采空区覆岩波速模型充分考虑了岩层形态、离层、断裂、裂隙发育和岩体扩容等对微震波传播路径和等效波速的影响,并通过定量确定微震波传播绕射路径增量和岩层波速折减,宏观表现出采空区地层结构的典型波速异向特征;③ 针对分层介质下的震源定位,在三维算例中选用异向等效波速模型的定位方法相较于全局平均波速模型,定位结果的平均误差由 9.755 8 m 降至 0.418 6 m,有效降低了定位误差;④ 以矿井大能量微震事件的井下微震定位结果为参照,在现场地面微震监测中应用采空区覆岩波速模型,得出该模型定位结果较待定波速而言更接近现场调查结果中确定的煤岩体破裂影响范围。综上,对于依赖波速模型的定位方法,根据地质结构特征建立相应的异向波速模型是高效开展微震监测,提高微震源定位精度的突破点之一。

In order to build a small-scale regional microseismic wave velocity model in a coal mine and improve the location accuracy of microseismic source in a complex geological structure of goaf, based on the characteristics of deformation, separation, development of faults and fissures and rock expansion in goaf overburden rock “three zones”, the wavevelocity structure of goaf overburden rock is described by constructing a wave velocity model of circular arc layer. Thediffraction propagation path increment of microseismic wave considering the deformation characteristics of rock and thefracture rock velocity reduction based on the time-average equation are proposed to modify the velocity model. Based onthe assumption of layered homogeneous media and the Snell’s law, the propagation path and travel time of microseismicwave are derived, and the anisotropic equivalent wave velocities in each direction are calculated. Based on the arrival timelocation theory, the difference between the measured time difference and the theoretical time difference is chosen to construct the objective function and the pattern search algorithm is used to solve the source location problem. A microseismiclocation method based on the anisotropic wave velocity model of goaf overburden rock is proposed. Through a 3D calculation example and the location application of coal mine ground microseismic monitoring, the feasibility and location effectof the proposed method are verified. Results show: ① Due to the wide distribution of goaf and the inevitability of microseismic wave propagating through goaf in coal mine geological environment, it is the key to establish the correspondinganisotropic wave velocity model according to the complex stratum structure characteristics of goaf in a coal mine for improving the location accuracy of microseismic source in mine environment. ② The wave velocity model of goaf overburden rock fully considers the influence of rock stratum morphology, separation, fracture, fissure development and rock expansion on microseismic wave propagation path and equivalent wave velocity. The microseismic wave propagation diffraction path increment and rock wave velocity reduction are quantitatively determined. The proposed model shows thetypical wave velocity anisotropy characteristics of goaf stratum structure. ③ For the source location in stratified media,compared with the global average wave velocity model, the average error of location results is reduced from 9.755 8 m to0.418 6 m by using the anisotropic equivalent wave velocity model in the 3D calculation example, which effectively reduces the location errors. ④ Taking the underground microseismic location results of large energy microseismic events asreference, the wave velocity model of goaf overburden rock is applied in the field ground microseismic monitoring. Andthe location results of the proposed model are closer to the influence range of coal and rock fracture determined in the fieldinvestigation results than the undetermined wave velocity. In conclusion, for the location method relying on the wave velocity model, the establishment of the corresponding anisotropy wave velocity model according to the characteristics of thegeological structure is one of the breakthrough points to carry out the microseismic monitoring efficiently and improve thelocation accuracy of the microseismic source.

国家自然科学基金资助项目(51774173);辽宁省“兴辽英才计划”资助项目(XLYC2007163);辽宁“百千万人才工程”培养经费资助项目(2021921023)

周琳力,贾宝新,潘一山,等. 采空区覆岩波速模型及微震源定位方法[J]. 煤炭学报,2023,48(5):2049−2064.

ZHOU Linli,JIA Baoxin,PAN Yishan,et al. Wave velocity model and microseismic location method of goafoverburden rock[J]. Journal of China Coal Society,2023,48(5):2049−2064.