Test on Water-Level Stabilization and Prevention of Mine-Shaft Failure by Means of Groundwater Injection

2014 
The Huang-Huai region is an important coal-mining area in China. Since 1987, many shaft-fracture disasters have occurred in this region. These accidents were a result of mining activities that induce the drawdown of water in aquifers within the mine, resulting in compression of the deep soil layers. This induces additional stress in the shaft wall and fracturing occurs once the total stress surpasses the strength of the concrete. Traditional treatment of shaft-wall fracture involves reinforcing the shaft wall with a wall ring, casing the shaft wall, creating a stress-relief slot, and grouting the surrounding strata. These methods are time consuming and require frequent re-treatment. In this paper, we present a method of water injection into the aquifer to stabilize the water level, and, thus, prevent shaft fracture. A water-injection test was conducted between March 6 and April 7, 2010 in the Jisan coal mine in the Huang-Huai region. As the water level measured in the observation holes rose, the shaft tower rose 0.80 mm on average. The ground surface rose 1.17 mm on average and the shaft wall rose 1.48 mm on average after the water injection. Accordingly, there was a gradual decrease in the compressive strain and increase in the tensile strain in the shaft walls. This approach of preventing shaft failure by water injection in the Jisan coal mine, thus, appears feasible.
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