New development of grouting water shutoff technolo

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New progress of grouting water shutoff technology in coal mines

water disasters in coal mines affect the progress and quality of mine engineering construction, worsen the working environment of workers, increase the drainage facilities and drainage costs of coal mines, and bring unsafe factors to the utilization and production of coal mines, especially in aerospace. In serious cases, even flooding accidents occur, causing heavy losses of life and property [1]. The hydrogeological conditions of coal fields in China are complex. At present, about 18% of the coal reserves to be mined in China are threatened by serious water damage. It is of great importance and urgent practical significance to prevent and control them. Water plugging by grouting is one of the important methods for mine water prevention and control. It has the obvious advantages of reducing the drainage burden of the mine, saving drainage power, reducing the cost per ton of coal, improving work efficiency and quality, strengthening the weak sections of the shaft and roadway, reducing the probability of water inrush, and extending the service life of the mine [2]

2. Development history of grouting water shutoff technology as a branch of grouting technology, grouting water shutoff develops with the development of grouting technology. As a new field of engineering technology, grouting water shutoff technology has only a history of more than 100 years. In 1802, France first applied the grouting method to the compound tide gate [3], and in 1856, Britain first used cement for grouting. From 1882 to 1920, it successively developed pneumatic grouting machine and water glass calcium chloride chemical slurry, and then successively developed chrome lignin, acrylamide and other slurry materials. Since the 1940s, a variety of new chemical slurries (such as lignin, urea formaldehyde resin, acrylamide, polyurethane, etc.) and modified cement slurries have come out successively, pushing the grouting water plugging technology to a new height. The development of grouting water shutoff technology in China began with the grouting water shutoff of coal mine shaft wall in the early 1950s [4]. Since the 1960s, China has successively developed a series of inorganic or organic grouting materials, and gradually established the grouting theory and grouting technology suitable for specific grout. After entering the 21st century, the research and application of grouting water shutoff technology has entered a peak period. Many aspects of grouting water shutoff technology, including material varieties, equipment and equipment, have achieved certain development. In recent years, grouting water shutoff technology has been widely used in various geotechnical engineering, and the technical and social benefits are also very significant. However, the grouting water shutoff technology itself is not mature and needs to be continuously improved

3 research status and research results of grouting water shutoff technology

grouting water shutoff technology includes hardware and software parts: the hardware part also includes grouting materials and grouting equipment, and the software part can simply classify grouting technology and grouting parameter calculation theory

3 and the future expenses were saved 1 grouting water plugging material

at present, most coal mine roadway water plugging grouting materials are cement or cement water glass. Their main advantages are low cost and wide source of materials. However, they are easy to shrink after hardening and produce small cracks. The cracks gradually expand under hydraulic scouring, so the water plugging effect is not ideal. Because they are granular materials, it is difficult to press in small cracks, so their application scope has certain limitations. The organic high water content material (HWM) developed by China Polytechnic University (Beijing) has the characteristics of low viscosity, the gel time can be manually adjusted and accurately controlled within a few seconds to hours, and is easy to be pressed into the deep micro cracks of rock mass. The formed gel requires high stone rate and low permeability. It has been successfully applied to the grouting and water plugging project in permeable rock strata. The reaction process and the consolidated body formed by the reaction with flowing sand are shown in Figure 1

3.2 grouting water shutoff equipment

the key equipment in the composition of grouting equipment is the grouting pump. At present, most of the electric adjustable speed high-pressure grouting pumps used in domestic grouting water shutoff projects are inconvenient to use because of their large weight. In recent years, China has developed a double liquid grouting pump [38] powered by emulsion, which can transport a variety of grouting water shutoff materials including polyurethane, but it needs emulsion as power, so it is inconvenient to use

qb-25 (12) series high-pressure double liquid grouting pump developed by China University of mining and Technology (Beijing), as shown in Figure 2, has reliable performance, convenient and safe use, and the maximum grouting pressure can reach 30MPa, which is suitable for sheet refining in 4.2.1 in narrow underground space. It has been successfully applied to the grouting water shutoff project in permeable rock strata in coal mines

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