Objective In order to grasp the influence of coal thickness change on the electromagnetic wave perspec-tive detection of the working face of the extra-thick coal seam,so as to accurately delineate the geological anoma-ly area and ensure the safe and efficient production of the working face.Methods According to the geological con-ditions of the coal face,the electromagnetic wave perspective numerical simulation of the coal thickness change was carried out by using 3D simulation software,and the analysis was carried out in combination with the explora-tion example of the working face.Results The results show that in the range of 0～20m coal thickness,with the decrease of thickness,the electromagnetic wave perspective field strength value shows a parabolic downward trend,which can be divided into three ranges:slow decrease(thickness≥9m),obvious decrease(9m＞thickness≥5 m)and rapid decrease(thickness＜5m).For the working face with a coal thickness of more than 10m is suit-able for analyzing the perspective electromagnetic wave response based on the relative thinning degree of the coal seam and the thickness of the coal in the thinning area:the thin coal area with a thinning degree of more than 1/3 of the normal coal thickness and a coal thickness of less than 8m has obvious response.The smaller the coal thickness in the thinning area,the more significant the reduction of the perspective field strength value.For the working face with coal thickness less than 10m,the perspective electromagnetic wave response can be analyzed only based on the relative thinning degree of the coal seam:the thin coal area with thinning degree＞1/4 of the normal coal thickness has obvious response,and the greater the thinning degree,the more significant the reduction of the perspective field strength value.The detection example of 1304 working face of Shaanxi Jinyuan Zhaoxian Mining Co.,Ltd.shows that the electromagnetic wave response characteristics of normal coal thickness change and thin coal area are consistent with the numerical simulation results;The scopes of thin coal areas and faults with a drop of over 1 m delineated by geophysical prospecting of the working face are consistent with the actual ex-posure ranges.Conclusion Using the electromagnetic wave response characteristics of coal thickness change can reliably explore the geological anomaly area in extra thick coal face.
NETL
NSTL
万方数据
