Since the 1970s, my country's coal mine water prevention and control has mainly followed the principle of "prevention first, combined with prevention and control", based on the investigation of hydrogeological conditions and adapting measures to local conditions. Different prevention and control measures are adopted for different types of water damage. There are various methods of water prevention and control, including dredging, blocking, and a combination of dredging and blocking. In the prevention and control of water damage in coal mines, we adhere to the 16-character policy of "predict and forecast, investigate when in doubt, explore first before digging, treat first before mining", and formulate corresponding "prevention, blocking, dredging, drainage and interception" based on the actual situation of mine water damage. "Comprehensive prevention and control measures (Zhong Yaping, 2001; Zhao Tiechui, 2007).
In the study of the water inrush mechanism, concepts such as "water inrush coefficient", "equivalent water-isolating layer" and the existence of "original conductivity" in the floor water-isolating layer have been proposed. It is believed that floor water inrush The mechanism is the comprehensive result of factors such as the water richness of the aquifer, the thickness of the water-proof layer and the existence of natural fissures, water pressure, ore pressure. In terms of floor water inrush prediction, new methods such as pattern recognition method, random information method and vulnerability index method have been well applied (Wu Qiang, 2006, 2007a, 2007b, 2009; Jin Dewu, 1998).
In terms of water drainage and pressure reduction, there are surface drainage, underground drainage, and combined upper and underground drainage. Hydrophobicity and pressure reduction are the main technical measures to prevent and control water damage in mines in my country. In addition to the widespread use of regular dewatering and drainage in China, the dewatering of thin-layer limestone water in Fengfeng Mining Area and Zibo Mining Area, and the dewatering work procedures and dewatering exploration methods for pressure reduction and Handan Mining Area have also been carried out.
In terms of grouting and water blocking, water blocking and interception are important methods to prevent and control water damage in mines in my country. There are relatively mature methods and experience in grouting to seal water inrush points under still water and moving water conditions, and grouting curtains to intercept flow at the periphery of mining areas. This type of work has been carried out in Jiaozuo, Fengfeng, Coal Dam and other mining areas, and in particular, the extremely large water inrush at Fangezhuang Mine in Kailuan was successfully blocked.
In addition, the improvement of drilling technology, the adoption of comprehensive three-dimensional exploration methods, the application of computer technology and the development of various software have played an important role in the quantitative study of coal mine water inrush conditions.
1. Leaving underground waterproof coal (rock) pillars
When carrying out mining projects under water bodies, under aquifers, on confined aquifers or near water-conducting faults, in order to To prevent surface water or groundwater from intruding or collapsing into the work site, it is necessary to set up a waterproof coal (rock) layer of a certain width or height to prevent mining. This part of the coal (rock) layer is called an anti-waterproof coal (rock) pillar or Waterproof coal (rock) pillar. Among them, there are fault waterproof coal (rock) pillars, well field boundary coal pillars, upper and lower horizontal (or adjacent mining area) waterproof coal (rock) pillars, flooded area waterproof coal (rock) pillars, and surface water body waterproof coal (rock) pillars. There are six types of pillars and alluvium waterproof coal (rock) pillars.
2. Underground water exploration and drainage technology
Underground water exploration and drainage refers to the use of advanced exploration methods in the mining process to identify the water-bearing structures on the roof, floor, sides and front of the mining working face. (Including subsidence pillars), aquifers, water-logged old kilns and other water bodies, the specific location and occurrence, etc., are intended to make necessary preparations for effective prevention and control of mine water damage (Liu Yang, 2008).
3. Hydrophobic pressure reduction technology
Hydrophobic pressure reduction refers to reducing the water pressure of the coal seam floor aquifer or coal layer aquifer to the safe water pressure for coal mining through drainage. The drainage and pressure reduction engineering system includes three parts: drainage engineering, drainage facilities and drainage engineering [1]. By formulating a reasonable hydrophobic and pressure-reducing mining plan, Kailuan Zhaogezhuang Mine has achieved safe and pressure mining under the threat of high-pressure Austrian gray water in the floor, and has achieved huge economic and social benefits.
4. Grouting water-blocking technology
Grouting water-blocking technology is one of the most important means of water prevention and control in coal mines. It is mainly used in pre-grouting and well completion before shaft excavation. After grouting behind the wall, blocking large water inrush points to restore flooded mines, intercepting source water to reduce water inflow from mines, and blocking water in tunnels through aquifers or water-conducting faults. For example, a huge water inrush occurred in the Renlou Mine of the Wanbei Mining Bureau on March 4, 1996. The water inrush volume reached 576m3/min at the peak period. The grouting water plugging technology was used to successfully block the water at the appropriate layer of the coal bottom in the collapse column. (Zhao Tiechui, 2007).
5. Pressure mining technology
The so-called pressure mining means that the coal seam floor is threatened by confined water, and the performance of the water layer between the coal seam floor and the confined aquifer is fully utilized, without taking any measures. , or a comprehensive water prevention and control technology to achieve safe mining after taking certain technical measures when national economic and technical conditions permit. In recent years, this technology has been extensively and in-depth researched in my country and has achieved remarkable results [11].
6. Waterproof gates and sluice walls
Waterproof gates and sluice walls are the main safety facilities for preventing and controlling water in coal mines. For mines with complex hydrogeological conditions or the risk of water intrusion and flooding, in the design and layout of underground tunnels, complete isolation facilities must be established, waterproof gates and sluice walls must be reserved at appropriate locations, and waterproof gates must be installed around the bottom of the shaft; In other areas where there is a risk of water intrusion, mining activities can only be carried out after waterproof gates and other waterproof isolation facilities are installed nearby to achieve zoning isolation (Wang Xinxiao et al., 2007).
7. Mine prevention and drainage technology
During the mining process, coal mines inevitably have to approach, expose or destroy aquifers (bodies). The water in the aquifer (body) will flow into the mining face due to losing its original balance conditions, thus causing water damage accidents. In order to ensure the safe production of coal mines, it is necessary to set up corresponding prevention and drainage systems. Mine waterproofing and drainage technology mainly includes three aspects: ground waterproofing, underground waterproofing and mine drainage. For example, the "August 17" water burst and well flooding accident in Huayuan, Shandong Province, although caused by heavy rain, also exposed outstanding problems in ground waterproofing in coal mines.
8. ANN technology for predicting small structures in front of coal seam mining
Small structures refer to small faults with a fault distance of less than 5m or some small-scale fissures and dissolved gaps. During the mine production process, these small structures have a great impact on working face mining and tunnel excavation, and play an important role in mine water prevention and control. In view of the shortcomings of the current small structure prediction methods in the tunnel mining process, ANN technology was introduced into the small structure prediction method in front of coal mine tunnel excavation, and research on new methods for prediction and forecasting of small structures in mines was carried out (Wu Qiang, 2007c).
9. Aquifer reconstruction and aquifer reinforcement technology
This technology is a grouting water control method developed in the mid-to-late 1980s. When it is necessary to use hydrophobic and pressure-reducing methods to achieve safe mining, but the cost of hydrophobic and dewatering is too high and it wastes groundwater resources, it is appropriate to use the grouting water control method of aquifer transformation and aquifer reinforcement. It mainly focuses on the prevention and control of water damage in coal seam floors, using grouting measures to transform the aquifer or strengthen the water-isolating layer, turning it into a relatively water-isolating layer or further improving its water-isolating strength (Wu Qiang, 2005). This technology is one of the more effective substantive measures to prevent and control floor water damage. This technology has been successfully applied in the Feicheng Mining Area of ??Shandong Province.
10. Visualized groundwater simulation evaluation software system (Visual Modflow) and mine water prevention and control
Visual Modflow is a three-dimensional groundwater flow and solute transport system that is currently popular internationally and unanimously recognized by peers in various countries. A standard visualization professional software system for mobile simulation evaluation. It can conduct equilibrium research on any water balance domain in mine water prevention and control work, helping users directly determine the recharge method, recharge size, and water quality of the recharge water source on the top, floor, or lateral recharge of the coal seam. In addition, it can also predict the amount of water inrush accidents that may be induced by the water-conducting fault structure in the mining area, which has very important practical value in the prevention and control of water at the inner boundary of the water-conducting area in the mining area (Wu Qiang, 2005; Dong Donglin, 2009 ).
11. Three-dimensional water-filled geological structure theory of North China coalfields
This theory was first proposed by Wu Qiang in 2000. The three-dimensional water-filled geological structure of multi-layered aquifer groups with close hydraulic connections formed by the communication of various types of hydraulic inner boundaries is the main hydrogeological feature of the North China type coalfield, and is also the basis for establishing the three-dimensional water-filled hydrogeological structure of this type of coal mine. The basis of the conceptual model. The inner boundary is the core of the three-dimensional water-filled geological structure theory of coal mines. In-depth and comprehensive research on the inner boundary system is the key to solving the problem of karst water inrush from the floor of North China coalfields.
The four basic types and various combination types classified according to the geometric characteristics of the inner boundary in space are of extremely important theoretical guidance for understanding the complexity of hydrogeological conditions in coal mines and adopting scientific and reasonable water prevention and control countermeasures. and practical value (Wu Qiang, 2000).
References
Dong Donglin, Wang Huanzhong, Wu Caixia et al. 2009. Analysis of seepage characteristics and water inrush risk of coal seam roof aquifers in fault and slip structure composite structural areas. Rock Mechanics and Engineering Journal, 28(2): 373～379
State Administration of Work Safety, State Coal Mine Safety Supervision Bureau. 2009. Regulations on Water Prevention and Control in Coal Mines. Beijing: Coal Industry Press. 1～80
Hua Jieming, Fu Yaojun, Bai Xiqing. 2006. Current status and development trends of hydrogeological exploration and environmental geological assessment in coal mining areas in my country. Coalfield Geology and Exploration, 34(3): 40～43
Jin Dewu , Ma Peizhi, Wang Yanfu. 1998. Stochastic information simulation and prediction of water inrush from the coal seam floor in North China. Hydrogeology and Engineering Geology, 26(6): 36～39
Li Wenjun, Hao Ping. 1997. Water damage in Datong local coal mines Current situation and prevention and control technology. Shanxi Coal, 17(5): 61～64
Liu Yang. 2008. The importance of water prevention and control in coal mines. Reform and Discussion, (27): 99
Ma Rungang. 2006. Water damage status analysis and prevention technology. Shanxi Coking Coal Science and Technology, (1): 14～15
Shang Dengying, Wu Qiang, Zhao Suqi et al. 2006. Guidelines for preventing and controlling water in coal mines. Beijing: State Administration of Work Safety, State Coal Mine Safety Supervision Bureau, 1～88
Wang Jianjun. 2008. Mine water inrush case analysis and pressure mining zoning. China Mining Engineering, 37(5): 39～41
Wang Xinxiao. Wu Qiang. 2007d. “Control” Water Interview with Wu Qiang, Leader of the Water Damage Prevention and Control Expert Team of the State Administration of Coal Mine Safety Supervision. Modern Occupational Safety, 10(74): 20～21
Wu Qiang, Dong Donglin, Qian Zengjiang, et al. 2000. On the three-dimensional water-filled geological structure theory of North China coalfields. Hydrogeology and Engineering Geology, (2): 47～49
Wu Qiang, Dong Shuning, Zhang Zhilong. 2007e. Mine water damage prevention and control. Beijing: China University of Mining and Technology Press. 1～9, 73～161
Wu Qiang, Xie Shuhan, Pei Zhenjiang et al. 2007b. New practical method for coal seam floor water inrush evaluation Ⅲ Application of ANN type vulnerability index method based on GIS. Journal of Coal Science, 32(12): 1301～1306
Wu Qiang, Pang Wei, Dai Yingchun et al. 2006. Evaluation of water inrush vulnerability of coal seam floor GIS and ANN coupling technology. Journal of Coal Science and Technology, 31(3): 314～319
Wu Qiang, Yang Liu, Zhu Bin, et al. 2009. "Vulnerability Index Method" Evaluation of Floor Water Inrush in Zhaogezhuang Mine Application in China Coal Geology, 21(6): 40～44
Wu Qiang, Yu Jia, Pang Wei et al. 2007c. Prediction technology of small structures in front of coal tunnel excavation based on ANN method. China Mining Journal of University, 36(4): 446～452
Wu Qiang, Zhang Zhilong, Zhang Shengyuan et al. 2007a. New practical method for coal seam floor water inrush evaluation II vulnerability index method. Journal of Coal Science, 32(11) ：1121～1126
Wu Qiang. 2005. Proceedings of the Sixth National Coal Industry Science and Technology Conference. Beijing: Coal Industry Press, 294～296
Zhao Suqi, Wu Qiang, Guo Qiwen et al. 2003. Technology for rapid control of water damage in coal mines through diversion grouting. Coal Science and Technology, 31(2): 27～29
Zhao Tiechui. 2007. Typical water damage cases and prevention technologies in coal mines across the country. Beijing: China University of Mining and Technology Publishing House. 185～192
Zhong Yaping. 2001. Research on comprehensive water prevention and control technologies in Kailuan Coal Mine. Beijing: Coal Industry Press. 539～542