Response Characteristics of Water-Bearing Goafs for Surface-to-Underground Transient Electromagnetic Method

2019 ◽  
Vol 24 (4) ◽  
pp. 557-567
Author(s):  
Zhihai Jiang ◽  
Lian Liu ◽  
Shucai Liu ◽  
Jianhua Yue
Keyword(s):  
Water Inrush ◽  
Geophysical Methods ◽  
Lateral Position ◽  
Relative Difference ◽  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Response Characteristics ◽  
Geophysical Model ◽  
Transient Electromagnetic ◽  
Vector Finite Element

Many of most serious disasters in coal mines around the world are attributed to underground flooding from water-bearing goafs. To ensure the operational safety in the deeper coal seams, water-bearing goafs must be clearly mapped to prevent water inrush accidents. Existing geophysical methods cannot fully meet this requirement. Building on the merits of the transient electromagnetic method (TEM) at the surface and in the mine, we propose a surface-to-underground transient electromagnetic method (SUTEM). We first analyze the differences between the surface TEM and SUTEM with a uniform half-space model. Secondly, we establish a geophysical model for water-bearing goafs and simulate the response signals at different depths with a vector finite-element method. Finally, we conduct a field experiment of SUTEM. The results of the simulation and experiment show: 1) When the surveying line is below the water-bearing goaf, the abnormal response information is mainly focused on the ascending segment of the electromotive force (EMF) curve, and the relative difference (RD) increases with the value of h/z decrease; 2) Appling SUTEM, we can accurately map the lateral position of the water-bearing goaf with the RD.

scholarly journals Simulation Research and Application on Response Characteristics of Detecting Water-filled Goaf by Transient Electromagnetic Method

2021 ◽  
Author(s):  
Tingye Qi ◽  
Xiaoming Pei ◽  
Guorui Feng ◽  
Huiru Wei
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Water Inrush ◽  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Induced Voltage ◽  
Measuring Point ◽  
Response Characteristics ◽  
Transient Electromagnetic ◽  
Water Accumulation

Abstract Water inrush disasters poses a great threat to the safe exploitation of coal resources. To solve this problem, the transient electromagnetic method(TEM) was proposed to accurately detect the water accumulation in the goaf. The electromagnetic response characteristics of different water-filled goaves were studied by electromagnetic field theory, numerical simulation and field verification. Through the models of 100% water accumulation, 50% water accumulation, 0% water accumulation, 100% water accumulation with collapsed rock, 50% water accumulation with collapsed rock and 0% water accumulation with collapsed rock goaf, the characteristics of induced voltage attenuation curves were studied. Meanwhile, the relationship between the attenuation voltage value and area of the transmitting coil and the depth of the goaf were also simulated. The results illustrate that the attenuation curve of induced voltage presented a regular exponential decay form in the 0% water accumulation model but existed abnormal exaltation for voltage in water-filled model. Through the linear fitting curve, it can be seen that the abnormal intensity of the induced voltage becomes stronger as the distance between the measuring point and the center of the target decrement. Moreover, the abnormal amplitude of the induced voltage increases with the rise of the water accumulation and collapsed rock will weakly reduce the low-resistance anomalous effect on the water-accumulated goaf. In addition, the response value of the attenuation voltage increased in second-order as the area of the transmitting coil increases, but decreased in third-order as the depth of the target body increases. The field detection results of the Majiliang coal mine also confirmed the theoretical analysis and the numerical simulation. The conclusions had important guiding significance for accurate detection of coal mine goaf.

Review of Geophysical Exploration on Mined-out Areas and Water Abundance

2019 ◽  
Vol 24 (1) ◽  
pp. 129-143
Author(s):  
Laifu Wen ◽  
Jiulong Cheng ◽  
Shaohua Huang ◽  
Jin Zhou ◽  
Yangchun Han ◽  
...  
Keyword(s):  
Geophysical Methods ◽  
Electromagnetic Method ◽  
Research Progress ◽  
Transient Electromagnetic Method ◽  
Water Abundance ◽  
Geophysical Exploration ◽  
Transient Electromagnetic ◽  
Seismic Methods ◽  
Electromagnetic Methods ◽  
Surface Borehole

With the increase in mining depth, the presence of goafs has become increasingly severe in mine safety. The accurate and effective detection of underground goafs and their water abundance is the key to ensure the safety of mine production. On the basis of the relevant research, this paper defines different goaf types from the perspective of geophysical exploration and discusses the geophysical prerequisites for goaf detection. DC methods, electromagnetic methods, seismic methods, and other geophysical methods on the ground and in the subsurface are reviewed and summarized using the method's principle, research status, and technical features. Research progress on the geophysical methods in goafs and their water abundance detection are introduced, including the electrical source short-offset transient electromagnetic method (SOTEM), the wave-field transformation and synthetic aperture of the transient electromagnetic method, and comprehensive detection. At the end of the paper, a direction for the development of coal mined-out areas and their water abundance detection is put forward, including information fusion technology, ground-airborne electromagnetic methods, magnetic resonance sounding (MRS), surface-borehole transient electromagnetic method, surface-borehole seismic methods, and seismic while tunneling technology. The application prospects of these methods are discussed, and the results of this study are expected to considerably improve the location precision and resolution of the goaf detection on the basis of the implications of these techniques.

scholarly journals Double-transmitting and Sextuple-receiving Borehole Transient Electromagnetic Method and Experimental Study

2017 ◽  
Vol 21 (2) ◽  
pp. 77-83
Author(s):  
Bo Wang ◽  
Shengdong Liu ◽  
Shining Li ◽  
Fubao Zhou
Keyword(s):  
Physical Simulation ◽  
Hot Spot ◽  
Electromagnetic Method ◽  
Electromagnetic Response ◽  
Transient Electromagnetic Method ◽  
Geophysical Exploration ◽  
Response Characteristics ◽  
Transient Electromagnetic ◽  
Geometric Difference ◽  
Radial Depth

With the continuous improvement of precision requirements for borehole geophysical exploration, the application of transient electromagnetic method (from now on referred to as TEM) in a borehole has become a hot spot. The conventional borehole TEM can only determine the longitudinal depth of the geological anomaly, the radial azimuth and depth cannot be resolved. A double-transmitting and sextuple-receiving borehole TEM is proposed, through which the radial anomaly is excited by the electromagnetic field generated by the double-emitting loops, and the azimuth and depth of the anomaly will be identified by the difference characteristics of the six receiving loops signals. In this paper, the response equations of the transmitting-receiving mode of double-transmitting and sextuple-receiving borehole TEM are deduced, and the response characteristics of the induction segment and the attenuation segment of the receiving loops are obtained based on the response equations under ramp function turn-off condition, providing the basis for theoretical analysis. Due to the negative value of the double-transmitting and sextuple-receiving transient electromagnetic response signals, a negative transformation algorithm under the double logarithmic coordinate system is proposed to provide the essential method for the analysis of two kinds of physical simulation experimental data of the radial azimuth and radial depth detection of the anomaly. The results show that the double-transmitting and sextuple-receiving borehole TEM has decent resolution ability in detecting the radial azimuth of the anomaly, and the effective resolution is 30°. The geometric difference among induced voltages of different measuring points can be used to evaluate the radial depth of the anomaly qualitatively. It is expected that the double-transmitting and sextuple-receiving borehole TEM can provide technical guidance for little borehole geophysical exploration in the fields of oil, natural gas, coal and basic engineering construction.

Configuration Detection of Substation Grounding Grid Using Transient Electromagnetic Method

2017 ◽  
Vol 64 (8) ◽  
pp. 6475-6483 ◽  
Author(s):  
Cigong Yu ◽  
Zhihong Fu ◽  
Gaolin Wu ◽  
Liuyuan Zhou ◽  
Xuegui Zhu ◽  
...  
Keyword(s):  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Grounding Grid

scholarly journals Application of Comprehensive Geophysical Prospecting Method in Water Accumulation Exploration of Multilayer Goaf in Integrated Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Lei Zhang ◽  
Lin Xu ◽  
Yong Xiao ◽  
NingBo Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Comprehensive Analysis ◽  
High Density ◽  
Electromagnetic Method ◽  
Mine Safety ◽  
Practical Significance ◽  
Time Base ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic

A coal mine in Datong is an integrated mine. At present, there is goaf in the upper and lower part of the mining coal seam. There is a lot of ponding in the goaf, which has great potential safety hazards for production. In order to find out the scope and location of ponding in goaf, the comprehensive geophysical exploration method combining transient electromagnetic method and high-density resistivity method is used to carry out the research. Firstly, the time-base, turn-off time, receiving delay, current, superposition times, and other parameters of the instrument are tested on the surface of known goaf to obtain the best instrument parameters, and the parameters are used to verify the feasibility of the research scheme; then, the transient electromagnetic method is used for large-area exploration on the surface of the mine, the suspected goaf ponding area is found through comprehensive analysis, and the high-density resistivity exploration is arranged in the suspected goaf ponding area. According to the obtained results, the scope and location of the goaf ponding area are accurately located through comprehensive analysis. The results show that there are two goaf ponding areas in the exploration area, which are located above the 8# coal seam currently mined; the range and location of goaf ponding area can be accurately obtained by using the comprehensive geophysical method of high-density electrical method and transient electromagnetic method. This method can provide reference for mine water prevention and control in Datong area and has great practical significance to ensure coal mine safety production.

Sign in / Sign up

Export Citation Format

Share Document