Study On Technology Of Soft Coal Seam Rib Spalling Preventing By Water Infusion With Shallow Holes

Based on analysis about status of coal seam infusion technology and soft coal seam preventing rib spalling technology and used coal's failure mechanism,strength theory and coal's wetting mechanism, the mechanism of shallow holes infusion at coal wall preventing rib spalling in soft coal seam was analyzed. Through the experiment of soft coal seam under the condition of different moisture content, analysis of mechanical properties of coal was got. Meanwhile field test was done and effects of shallow holes infusion at coal wall preventing rib spalling in soft coal seam was verified.In the laboratory, the coal samples'mechanical properties determination tests under the condition of different moisture content was done. The coal samples were from Zhuxianzhuang mineⅡ863 fully mechanized coalface. The test results obtained: The coal's cohesion and shear strength at moisture content between 2% ~ 12% increase monotonically, shows that increasing coal moisture content in certain range can change mechanical properties of coal and effectively improve the cohesion and shear strength. In certain circumstances of moisture content, with confining pressure increasing, the shear strength and compressive strength was increasing. In certain circumstances of confining pressure, with the increase of the moisture content, compressive strength drab monotonically.Through the experiment, the contact angle of coal water is 69.8 degrees and the hydrophilic was poorer. In order to enhance the coal's wetting and improve the effect of shallow holes infusion to wet the coal, adding surfactants in laboratory to improve coal wetting effect was investigated. After analysis of experimental results obtained in the experiment, surfactant in aqueous acid 0.1% sodium dodecyl stupid to increaseⅡ863 fully-mechanized coal wetting was the best results.In the paper, field test of shallow holes infusion at coal wall preventing rib spalling in Zhuxianzhuang mineⅡ863 fully mechanized coalface was done and the plan of shallow holes infusion at coal wall was designed and implemented. Key technologies of shallow holes infusion at coal wall was confirmed: water hole infusion spacing was 9.0m;deep hole was 5.0 m; dip angle of hole was 30°~ 40°; seal depth was 2.0 ~ 2.5 m; injection pressure was 4 ~ 8MPa. Through every morning (maintenance) implementing shallow holes injection measures, good technical effects and social economic benefits were achieved: The problem of serious rib spalling in mining face was effectively controlled; the labor intensity was reduced; labor productivity was improved; a lot of support materials was saved; the cost of tons of coal was reduced; the home using tv of the mining face coal cutter was improved which increased to 8.8 million tons per month from 5 million and 78% higher than ever.