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Abstract No.5 coal of Fenyuan Coal Industry is affected by limestone water, in order to achieve safe recovery mining, the risk of floor water breakout of No.5 coal seam was evaluated, and the influencing factors of water breakout were elaborated, meanwhile, holes were constructed in the floor to test the water blocking performance. The results showed that there were broken zones in the bottom slab, and the depth of damage of the bottom slab and the height of the pressurized water conduction zone exceeded the height of the water barrier after the recovery mining, so there was a risk of water breakout. Measures like retaining coal pillar, grouting reconstruction of floor were taken to prevent water burst, the safe recovery of the first mining face was realized.
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