Research On Special Thick Coal Seam Overburden Broken Rule In Fully Mechanized Caving Under Aquifer

The research on special thick coal seam overburden broken rule in fully mechanizedcaving is rare at home and abroad, but movement and failure of overburden are directlyrelated to water flowing fractured zone, it can make surface and underground water in miningscope pour into underground and threaten the safety of underground operation. Due to thisfact, it has important economic and social significance to study special thick coal seamoverburden movement and failure law.Based on fracture and elastic-plastic mechanics, combining the underground pressuretheory with special mining theory closely, establishing every kind of mechanical model on theprocess of overburden failure and analyzing each of them respectively, according to the stressof overburden, this paper summarizes the overburden structure and damage characteristics offully mechanized caving face. On this basis, water flowing fractured zone morphology,growth and height variation characteristic are analysed, finally, the main factors of theinfluence of water flowing fractured zone height development are summarized.Relying on the key lab of ground controlling in Xi’an University of Science andTechnology, according to the engineering geological conditions of Hujiahe coal mine inBinchang mining area, fully mechanized caving process is studied by physical simulation testmethod, then rock mass migration and crack extension principles of overburden duringmining are analyzed, the height of water flow fractured zone is14~16times than that ofmining, it also has curve relationship with advance distance, and the sandstone aquifer ofLuohe group can cause water bursting.Using finite difference numerical simulation method, the rule of overburden failureunder aquifer is studied, then the failure field, stress field and displacement fieldcharacteristics of overburden during mining are analyzed, after that, the possibility of waterbursting disaster is expected. According to simulation results, the paper summarizes strata failure rule of fullymechanized caving face, and optimizes empirical formula using mathematical method, theexpected results compared with the actual situation of production unit have the higheraccuracy, better reliability and certain reference significance.