An Influence Study of Face Length Effect on Floor Stability under Water-Rock Coupling Action

The Taiyuan Formation limestone aquifer and Ordovician are widely distributed in the coal seam floor of measures North China; water hazard safety problem stope under influence mining is very prominent. risk inrush from closely related to degree full exploitation, so it necessary study stability conditions, especially working face length effect on stability. Through numerical simulation water-rock coupling action, mine pressure behaviors water-resisting different lengths were analyzed based measured formation permeability coefficient. Fish program was used adjust rocks entering plastic failure state into a strain softening model investigate effect, damage floor, morphology deformation bearing capacity zone. results show following: (1) one main factors mode surrounding stope; (2) as increases, obvious relief zone presents staged change, at roof an “reverse saddle shape”; (3) closer more remarkable rock characteristic because compaction action gangues caving roof; (4) mass close undergoes local tensile failure, near wall two sides mainly bears compaction-shear leading compression-shear water-conducting fractures. can provide reference for taking precautionary above confined aquifer.