1. College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China 2. Research Center of Green Mining Engineering Technology in Shanxi Province, Taiyuan 030024, China
After the formation of water-filled goaf in coal mines, the distribution patterns and locations are different and unclear. Therefore, it can easily cause serious water hazards. In order to accurately locate the water-filled goaf and study its electromagnetic response characteristics, the authors chose the Datong Majiliang coal mine as the engineering background, used acrylic glass shelves as the experimental platform, and took similar simulation materials as each rock layer to design the physical experiment of transient electromagnetic detection in the water-filled goaf under different water accumulation and existence situations of collapsed rock masses. The results demonstrate that, when the goaf is filled with water, the induced electromotive force curve will be affected by the low resistance effect during the attenuation process and produce an abnormal "upward" phenomenon, and the greater the water filling, the more obvious the abnormal amplitude is. The existence of collapsed rock mass will limitedly weaken the abnormal interference of low resistance. When the goaf is not filled with water, the induced electromotive force curve decays normally, and the impact of the collapsed rock mass is negligible.
Formation distribution table of No.1 coal seam in Shendong coal mine
岩层
层序
铺设高度/m
配比号
砂子/kg
石灰/kg
石膏/kg
水/kg
细砂岩
5
0.03
546
26.19
2.09
3.15
3.15
粉砂岩
4
0.20
637
125.50
6.50
14.50
14.50
中砂岩
3
0.05
537
47.22
2.82
6.61
5.69
煤
2
0.1
873
62.00
5.50
2.25
7.00
砂质泥岩
1
0.08
673
50.64
5.12
2.24
5.76
总量
0.46
311.55
22.03
28.75
36.10
Proportion of similar mateials in rock layers
Schematic diagram of physical simulation model
Schematic diagram of resistance test system
模拟岩层
细砂岩
粉砂岩
煤层
中砂岩
砂质泥岩
含水层
电阻率/(Ω·m)
(3.4~3.5)×103
(7.6~7.7)×103
(2.5~2.6)×103
(6.8~6.9)×103
(2.6~2.7)×102
1~5
Electrical characteristics of similar simulated specimens
Layout of surveying lines and points
Curves of decay electromotive force of water-filled goaf in different states
Attenuation electromotive force curves in goaf with different amounts of accumulated water(a) and the increase characteristics of induced electromotive force(b)
充水状态
采样时间/ms
0.5645
0.7005
0.8695
1.0800
1.3405
1.6640
2.0660
2.5645
3.1840
全充水
3.6301
3.5741
3.5219
3.4630
3.3243
3.1076
2.8268
2.4148
2.0729
充1/2水
3.4773
3.3705
3.2642
3.0884
2.8599
2.5970
2.2564
1.9737
1.7080
未充水
3.2616
3.0930
2.9304
2.6923
2.5167
2.3015
2.0897
1.7868
1.6064
Response value of attenuation electromotive force in goaf with different water filling μV/A
Curves of attenuation electromotive force in the water-filled goaf with different existence status of collapsed bodies
充水状态
采样时间/ms
0.5645
0.7005
0.8695
1.0800
1.3405
1.6640
2.0660
2.5645
3.1840
全充水
3.6301
3.5741
3.5219
3.4630
3.3243
3.1076
2.8268
2.4148
2.0729
全充水含垮落体
3.5917
3.5320
3.4377
3.3002
3.1049
2.9011
2.6377
2.3024
1.9881
充1/2水
3.4773
3.3705
3.2642
3.0884
2.8599
2.5970
2.2564
1.9737
1.7080
充1/2水含垮落体
3.4071
3.2613
3.0995
2.9220
2.7115
2.4262
2.1357
1.8610
1.6282
Response values of attenuation electromotive force of water-filled goaf in different the existence status of collapsed bodies μV/A
Amplitude reduction characteristics of attenuation electromotive force response under different water-filled conditions
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