Deep-hole water injection technology of strong impact tendency coal seam—a case study in Tangkou coal mine

Abstract

The implementation of coal-seam water injection can change the physical and mechanical properties of coal, can improve the coal storage limit, prevent and control rock burst, prevent coal and gas outburst, and reduce dust concentration in underground operations. However, there are still many shortcomings such as the poor sealing effect and the lack of coal seam permeability. In order to study coal softening through water injection and its effect of reducing the coal’s impact tendency, we examine the impact tendency, coal seam injection, water injection additive, water injection hole sealing, and coal seam stress-relief effect of coal seam on LW5304 experimentally and through engineering application. The results show that this method can be used to reduce the coal’s impact tendency, if the samples are soaked. Triton X-100 additive can effectively reduce the polarity of water and the surface tension, while improving the coupling effect of water and coal and the wettability of coal. The “pure polyurethane + cement slurry + cement mortar” sealing process can be used to avoid water injection leaking. The water content of LW5304 coal seam is 3.2~4.2% after water injection, and the average increase of moisture content is 1~2.5%. In addition, the number of coal-stress early warning is reduced, and micro-seismic monitoring shows that the average energy is reduced as well. Therefore, water injection in coal seam is considered a good method for relieving stress.