A reinforcement method of floor grouting in high-water pressure working face of coal mines: a case study in Luxi coal mine, North China

The working face is seriously threatened by limestone aquifer with high-water pressure in coal seam floor when Permo-Carboniferous coal is mined in North China Coalfield. Mine water control has become one of the major technical problems in coal mine production. Grouting transformation for limestone aquifer is an effective means to guarantee mining safety. A case of the 16,104 working face of the Luxi coal mine was studied in this paper. The results by the method of water-inrush coefficient (WIC) showed that there was a great risk of water inrush in 16,104 working face. There were differences between water-rich areas of floor aquifer obtained by geophysical methods and the areas with large water inflow by drilling exploration. The geophysical methods were performed again in the water-rich areas using traditional grouting method, results showed that the water-rich areas changed places, indicating that the effect of traditional grouting was not obvious. Grouting of areas of high-water inflow has reduced the water inflow. However, the grouting also has changed the water flow paths. What's more, the drill holes sealed poorly will also lead to the change of the position of the water-rich areas. To enhance overall grouting efficiency and cut down the repeated grouting times, a secondary grouting-reinforcement method was proposed to ensure amount grout injected into aquifer. The results showed that the grouting reinforcement was successful, which can provide reference for the treatment of floor confined water of North China Coalfield.

Automated summary

The working face in North China Coalfield is seriously threatened by a high-water pressure limestone aquifer in the coal seam floor. Mine water control has become a major problem in coal mine production. This study focuses on grouting transformation for limestone aquifer in the Luxi coal mine. Results showed that the traditional grouting method had limited effectiveness and could change water flow paths. Poorly sealed drill holes also led to changes in the position of water-rich areas. A secondary grouting-reinforcement method was proposed to enhance grouting efficiency.