煤岩巷道掘进过程电磁辐射的时空分布规律研究

RESEARCH ON TEMPORAL-SPATIAL DISTRIBUTION LAWS OF ELECTROMAGNETIC EMISSION DURING TUNNEL EXCAVATION OF COAL ROCK

首先通过FLAC3D软件对矿山巷道掘进过程中煤岩内部应力场分布规律进行数值模拟;然后在煤岩变形破裂过程中产生的电磁辐射(EME)强度与煤岩内部应力之间的力电耦合方程的基础上,研究巷道掘进过程中产生的电磁辐射信号的时空分布规律。研究结果表明:模拟应力值的变化规律与理论分析和现场实际测定围岩应力的显现规律是一致的,从而说明该方法能正确模拟现场煤岩在开挖过程中受采动影响时内部应力场的变化规律;电磁辐射(EME)信号强度在巷道监测空间的变化规律是:沿巷道高度方向为顶底板处小于中部,在水平方向的分布则是左、右端均小于中间;EME信号的时变规律则是,随着时间的增加,EME信号在同一监测点的变化先是逐渐增加,增加到一定程度后趋于平缓,反映了煤岩体内部应力的变化规律。现场实际测定结果亦表明,钻孔内不同深度所测定电磁辐射强度的规律变化基本上与模拟结果相同,从而说明用力电耦合方法来研究煤岩变形破裂电磁辐射的时空分布规律是可行的,可以有效地指导实践。

First the distribution laws of stress fields in the course of mine tunnel excavation are simulated by means of FLAC^3D software. Then, according to the coupling equation between electromagnetic emission（EME） and stress fields during the deformation and fracture of coal or rock, the temporal-spatial distribution laws of EME during mine tunnel excavation are also researched. The results show that the changing rules of simulated stress are in accordance with theoretical ones and practical strata stresses, which shows that the FLAC3D can appropriately simulate the changing rules of stress field in the course of mine tunnel excavation. The spatial distribution laws of EME are that the EME signals have smaller values when being monitored in the roof of tunnel than those in the middle of tunnel along the height of tunnel, and the EME signals have smaller values when being monitored in the left side or right side of tunnel than those in the middle of tunnel along the horizontal direction of tunnel. The EME signal in head-on area along the way of tunnel excavation increases constantly to the summit value, and then falls down. The temporal distribution laws of EME are that EME in the same monitoring place increases firstly, and then increases slightly with time. The change of EME strength reflects the change of inner stress aRer excavation. The practically measured results of EME have the same changing tendency with the simulated results, which also testifies the feasibility of the coupling method between EME and stress to study the temporal- spatial distribution laws.