Preventing water-inrush from floor in coal working face with paste-like backfill technology.

In the view of the situation where great economic loss often occurs during mining deep coal seams in Feicheng coal field due to water inrush from the floor Ordovician limestone aquifer, the floor "lower four-zone" theory was used as a guide. 81006 working face of Caozhuang Coalmine in Feicheng coal field was taken as the research background, and paste filling technology was proposed to inhibit or reduce the damaged floor depth caused by mine ground pressure in order to prevent water inrush from the floor Ordovician limestone aquifer. Glue material, coal gangue powder, and fly ash were selected as filling material, and a ground filling system, including a material production system, storage material system, power supply and water supply system, automatic control and measurement system, monitoring and control communications system, emergency response system, and underground filling system, including pipe conveyor system and working face blocking grout loss system, were established to achieve effective filling goaf. Field stress monitoring and floor damaged depth measurement showed that when reaching a steady state after a period of time, paste filling working face not only restored to the original stress state but also significantly reduced the floor's damaged depth caused by mine ground pressure. This verifies that working face with paste-like backfill technology is a very effective measure to prevent water-inrush from the floor.