The Exploration Of Ultra-High Water Floeing Fractured Zone In Shendong Mining Area

Jurassic coal is mainly mined in Shen Dong Mining Area, burial depth of coal-bed is changed from 100m to 400m,the strength of overburden strata from soft weak to medium hard, the development of pre-existing fracture of Mining Area has large difference, in the mining practice, water-inrush accident which is caused by ultra-high guide water flowing fractured zone have happened at coal face, it has a serious effect on mine safety production.This paper uses the methods of theoretical research, numerical simulation and field measurement to study the features and parameters of overburden strata destroyed zone, and making focus on discussion of the main factors which caused the ultra-high guide water flowing fractured zone.Through the three belts and distribution characteristics of overburden rock, it can be known that the caving zone height of the 3 mines is in normal range, but the height of Guide water fracture zones is very different, the height of guide water fracture zones of Cuncaota coal mine is 25.21m, crack-production ratio is 10.9,between the theoretical height of hard rock and soft rock, and consistent with the occurrence condition of rock strata, but the guide water fracture zones of Buaitai coal mine and Bulianta coal mine is ultra-high, respectively 146m and 142.5～155.95m, the crack-production ratio is 48.7 and 32.39～35.44,is 1.9～3 times of the theory water flowing fractured zone height of medium harden rock.Making a comprehensive analysis of multiple factors through methods of theoretical research and UDEC numerical simulation, the main factors of ultra-high guide water flowing fractured zone are the mechanical structure of overburden strata and the difference of rock mass structure. The strength of bedrock of Cuncaota coal mine is great, the features of overburden strata movement are thin strata, multi-stages, rapid development, multiple collapse of small range rock, the rock is easy to broken and expansion development, timely filling gob area, easing the fractured zone development of strata,it height is anastomosed with height of water flowing fractured zone under the condition of medium hard rock and belongs to normal water flowing fractured zone; however, the strength of bedrock of Buertai coal mine is relative weak, the development of pre-existing fracture of the rock of middle-lower bedrock change the complete form of the rock, making a qualitative change on the rock structure, the rock is easy to collapse. The features of overburden strata movement are thick strata, multi-stages, slow development, synchronously collapse of multi-rock, leading a big abscission layer space, which is easy to connect to pre-existing fracture, forming ultra-high guide water flowing fractured zone.