scholarly journals Identification of Hydraulic Connection Points between Different Confined Aquifers in the Liyazhuang Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhenghe Liu ◽  
Peiyun Zhao ◽  
Lusheng Yang ◽  
Jingui Zhao ◽  
Hailong Ye ◽  
...  
Keyword(s):  
Flow Field ◽  
Coal Seam ◽  
Numerical Simulations ◽  
Water Level ◽  
Coal Mine ◽  
Prevention And Control ◽  
Water Inrush ◽  
Hydraulic Connection ◽  
Contact Points ◽  
And Control

Water inrush from coal seam floors is one major geological obstacle hindering safe and efficient production activities in mines. Determining the source of water inrush can facilitate its prediction and guide decisions regarding measures for prevention and control. The process of identifying the location of hidden hydraulic contact points in different confined aquifers forms the basis of hydrogeological explorations. It is also the basis for categorizing mine areas prone to water inrush and making qualitative decisions regarding the prevention and control of water inrush. In this study, the positions of hidden hydraulic contact points between the Ordovician Fengfeng and Shangmajiagou formations in the basement of the Liyazhuang coal mine were determined using numerical simulations of the flow fields. First, each node of the finite element grid was considered as a water inrush point to determine the water level at other nodes. Subsequently, the error between measured and simulated water levels, determined based on the flow fields, was determined using the least squares method. The node with the minimum error was then considered as the hidden hydraulic contact point. The simulation results for the flow field indicate a distance of 5000 m between the hydraulic connection and the water inrush points located between the peak formation and the Majiagou aquifer in the Liyazhuang coal mine. Furthermore, the hydraulic relationship between them is poor. Observational data of water inrush from the floor of the No. 2 coal seam and the water level of the confined aquifer in the Liyazhuang coal mine, including the water quality test data of different Ordovician ash aquifers, show that the source of water inrush from the floor of the No. 2 coal seam is the aquifer of the Fengfeng Formation. This finding is consistent with the results of the numerical simulations of the flow field. The results demonstrate that, in mining areas subjected to high pressures, numerical simulations of the flow field can serve as an effective tool for determining the location of hidden hydraulic contact points.

scholarly journals Prevention and Control of Hydrogen Sulphide Accidents in Mining Extremely Thick Coal Seam: A Case Study in Wudong Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xuchao Huang ◽  
Enmao Wang ◽  
Gang Wang ◽  
Jiuyuan Fan
Keyword(s):  
Molecular Weight ◽  
Coal Seam ◽  
Hydrogen Sulphide ◽  
Coal Mine ◽  
Prevention And Control ◽  
Coal Mines ◽  
Dynamics Simulation ◽  
Porous System ◽  
Coal Stratum ◽  
And Control

Hydrogen sulphide is a toxic gas often present in coal seams and seriously threatens the lives and health of underground workers in coal mines. In this study, we theoretically modelled hydrogen sulphide generation in extremely thick underground coal mines with the +575 level #45 coal seam of Wudong Coal Mine as an example and obtained the on-site hydrogen sulphide emission pattern and spatial distribution features by combining field measurements and computational fluid dynamics simulation. The results showed that hydrogen sulphide mainly exists in the coal porous system in an adsorbed state. Because hydrogen sulphide has a molecular weight greater than the average molecular weight of air molecules, its concentration decreases with the increase of altitude to the bottom plate. When mining the upper stratified coal stratum, it diffuses widely in the working space; while when mining the lower coal stratum, it mainly concentrates at the bottom of the working face. Based on these analyses, on-site treatments were carried out using mixtures with different concentrations of sodium carbonate and sodium bicarbonate. In addition, different combinations of catalysts as well as type A and type B wetting agents were also tested. Eventually, a neutral KXL-I absorbent was developed, and the process of preinjecting absorbent and spraying absorbent was designed. The results showed that the newly developed KXL-I absorbent has high hydrogen sulphide absorption ability and is suitable for use as an absorbent in Wudong Coal Mine; preinjecting and spraying the absorbent can effectively prevent hydrogen sulphide disasters in the +575 level #45 coal seam in Wudong Coal Mine with the optimal final concentration of 0.9% and the absorption rate of 87% at the shearer of 66.6% at the support. Overall, our study provides valuable information for the prevention and control of hydrogen sulphide disasters in coal mines.

scholarly journals System for Prevention and Control of Old Goaf Water during Coal Mine Re-mining

2021 ◽  
Author(s):  
Shuning Dong ◽  
Xiaolong Li ◽  
Liuzhu Ma
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Prevention And Control ◽  
Small Scale ◽  
Target Area ◽  
Geophysical Exploration ◽  
Blind Area ◽  
Mining Face ◽  
And Control ◽  
Water Disaster

Abstract One integrated mine was currently threatened with an old goaf water disaster, therefore, the development of an advanced detection-guarantee system for roadway excavation with no blind area was imperative. Further, multiple geophysical exploration in combination with two types of boreholes were used to explore and drain water technology, with the anomalous geophysical area as the target area, The conventional borehole with the largest water outflow was taken as the target spot, at a low elevation of the mining area, and a remote directional borehole was used to drill into the old goaf along the stable rock strata below the coal seam floor to intercept the dynamic recharge water, which increased the efficiency of roadway excavation 4–9 times. The ‘isolated island’ old goaf water in the mining face was controlled through multiple geophysical exploration combined with the full-coverage exploration technology by conventional boreholes, and the water-rich anomalous area and geological anomalous area were determined, thus ensuring the safety of the mining face in terms of old goaf water. The technology for advanced short-distance exploration, advanced estimate, roadway exploration, and dynamic old goaf water with drainage was used to comprehensively guarantee real-time, safe mining. This system for the prevention and control of old goaf water was applied to a control project for the old goaf water disaster in the 101 mining face. At present, 1.37 Mt of coal has been safely mined from this mining face. The technical system has improved The Detailed Rules for Water Disaster Prevention and Control of Coal Mine (NCMSA 2018), and improved the technology for the prevention and control of old goaf water under conditions where the upper portion in the same coal seam was destroyed by a small-scale coal mine and re-mining.

scholarly journals Cause Analysis and Prevention of Hole Collapse by Water Injection and Dust Removal in Qi Panjing Coal Mine

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Hua Guo ◽  
Hai-Qiao Wang ◽  
Shi-Qiang Chen ◽  
Zhi-Rong Wu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Prevention And Control ◽  
Water Injection ◽  
Economic Benefits ◽  
Dust Removal ◽  
Drilling Depth ◽  
Key Technologies ◽  
Complete Set ◽  
And Control

To solve the “special coal seam” with complex coal seam structure, fault phenomenon, and many gangue layers and complex gangue lithology in Qi Panjing coal mine, the problems such as hole collapse and blockage of coal seam water injection dust removal drilling are caused. From the aspects of drilling layout, drilling technology, and gangue material consolidation, a complete set of key technologies for prevention and control of water injection and dust removal in “special coal seam,” have been formed. Seven boreholes have been drilled in I020902 return air roadway of Qi Panjing coal mine, and field comparative test has been carried out. The results show that: after adopting the complete set of key technologies of drilling prevention and control, the drilling depth is 85-100 m, the average depth is 98 m, and the drilling depth of coal seam water injection can reach 170-185 m; the footage per cycle is greatly improved, with the minimum increase of 30.86%, the maximum increase of 46.38%, and the average increase of 36.77%, to save drilling time and bring good economic benefits, and there is no collapse in the borehole hole, to ensure the safety of production. It has a good reference, and practical guiding significance for other coal mining faces, especially for “special coal seam” working face.

scholarly journals Controlling Mechanism of Rock Burst by CO2 Fracturing Blasting Based on Rock Burst System

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Tianwei Lan ◽  
Chaojun Fan ◽  
Jun Han ◽  
Hongwei Zhang ◽  
Jiawei Sun
Keyword(s):  
Coal Mining ◽  
Rock Burst ◽  
Coal Mine ◽  
Prevention And Control ◽  
Stress Measurement ◽  
Tectonic Stress ◽  
Microseismic Monitoring ◽  
Time Space ◽  
Controlling Mechanism ◽  
And Control

Rock burst induced by mining is one of the most serious dynamic disasters in the process of coal mining. The mechanism of a rock burst is similar to that of a natural earthquake. It is difficult to accurately predict the “time, space, and strength” of rock burst, but the possibility of rock burst can be predicted based on the results of microseismic monitoring. In this paper, the rock burst system under the tectonic stress field is established based on the practice of coal mining and the result of mine ground crustal stress measurement. According to the magnitude of microseismic monitoring, the amount of the energy and spatial position of the rock burst are determined. Based on the theory of explosion mechanics, aiming at the prevention and control of rock burst in the coal mine, the technique of liquid CO2 fracturing blasting is put forward. By the experiment of blasting mechanics, the blasting parameters are determined, and the controlling mechanism of rock burst of liquid CO2 fracturing blasting is revealed. The application of liquid CO2 fissure blasting technology in the prevention and control of rock burst in Jixian Coal Mine shows that CO2 fracturing blasting reduces the stress concentration of the rock burst system and transfers energy to the deeper part, and there is no open fire in the blasting. It is a new, safe, and efficient method to prevent and control rock burst, which can be applied widely.

scholarly journals An Index of Aquiclude Destabilization for Mining-Induced Roof Water Inrush Forecasting: A Case Study

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2170 ◽  
Author(s):  
Gangwei Fan ◽  
Shizhong Zhang ◽  
Dongsheng Zhang ◽  
Chengguo Zhang ◽  
Mingwei Chen ◽  
...  
Keyword(s):  
Water Level ◽  
Coal Mine ◽  
Critical Role ◽  
Water Inrush ◽  
Threshold Value ◽  
Control Measures ◽  
Assessment Index ◽  
Risk Levels ◽  
Upper Aquifer

Aquiclude plays a critical role in the occurrence of mining-induced roof water inrush in underground coal mines. This paper proposes an assessment index for the evaluation of aquiclude stability and a threshold value of water inrush from the roof, based on a case study of roof water inrush accidents in Cuimu coal mine, China. The relation between roof water inrush and water level variation in the aquifer, and the characteristics of aquiclude deformation, were studied in this assessment. Using the developed assessment criteria, the likelihood of roof water inrush was categorized into different risk levels, which were followed by a proposal for roof water inrush control measures. The main findings of this study are: a) in Cuimu coal mine, the waterbody in the bed separation between the upper aquifer and the aquiclude directly causes the inrush, and inrush occurs after the water level declines in the aquifer; b) tension-induced horizontal strains of aquiclude can be regarded as the index to evaluate the stability of aquiclude affected by underground coal mining—roof water inrush occurs when the maximum horizontal strain reaches a threshold of 10mm/m—c) based on the critical mining height for aquiclude instability, and the different thicknesses of barrier layers, high-risk zones are identified and inrush controls are proposed.

Prevention and Control Technology Research on Rock Burst of Fully Mechanized Caving Faces and Gob-Side Entry

2013 ◽  
Vol 353-356 ◽  
pp. 303-306
Author(s):  
Zhi Chao Tian ◽  
Long Hao Dong ◽  
Min Ma ◽  
Ye Jiao Liu
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Similar Condition ◽  
Economic Benefit ◽  
Prevention And Control ◽  
Scientific Basis ◽  
Surrounding Rock ◽  
Control Technology ◽  
Technology Research ◽  
And Control

According to the actual monitoring data of mining environment and rock burst happening on the 3511 fully-mechanized workface in Anyuan coal mine, the research of the rock burst on the workface and its surrounding rock of gob-side entry is done and the reasonable supporting scheme is determined. The research results are of great guiding importance to the coal mining that has similar condition, provide scientific basis for the control technology of rock burst on the workface and its gob-side entry as well as the reasonable identification of support parameters on the gob-side tunnel, and supply technology protection in order to accelerate the advancing speed of workface. Finally it can produce larger economic benefit.

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