Study on disaster-causing characteristics and control of mining-induced damage seepage evolution of coal seam floor

In the process of coal seam mining, the coupling effect of mining disturbance and high confined water is easy to induce the penetration of floor cracks and the sudden increase of seepage, which seriously threatens the safety production of the mine. In order to accurately reveal the disaster-causing characteristics of mining-induced damage and seepage of coal seam floor under the condition of confined aquifer, and scientifically and effectively control the floor water disaster, based on the engineering geological conditions of Suancigou Coal Mine, the multi-field coupling mechanism is comprehensively considered, and the numerical calculation model of fluid-solid coupling of fine floor is established. The stress field distribution, plastic damage development and dynamic response evolution characteristics of seepage field in the whole process of working face mining are systematically explored. The results show that after the mining disturbance of the working face, there is a significant stress concentration effect at the edge of the goaf and in front of the coal wall, and the plastic yield failure and micro-fracture damage expansion occur first in the shallow rock mass of the floor. With the continuous advancement of the working face, the damage fissures of the floor rock mass gradually sprout, expand and connect with each other, and the permeability of the rock layer is significantly improved. The confined water continues to migrate and enrich along the high permeability damage fissure zone to the interior of the goaf, and gradually forms the dominant water conduction channel, which induces the hidden danger of floor water inrush. Water inrush from coal seam floor is a chain instability disaster-causing process of multi-factor coupling of mining stress redistribution, plastic damage gradual expansion, fracture network conduction and confined water seepage migration. After the prevention and control, the average water permeability of the floor decreased from 1.55 Lu to 0.13 Lu, with an overall decrease of 87.35 %, and the water-proof and anti-seepage performance of the floor was greatly improved. The research results can provide theoretical support and practical guidance for the stability control of coal seam floor and water disaster prevention and control in water-rich environment.