Study on Development Law of Water Conducted Fracture Zone in Top Coal of Fully Mechanized Top Coal Caving Mining Face

In order to study the overburden strata failure law and water conducted fracture zone development law under the condition of the fully mechanized top coal caving mining in Lu 'an Mining Area,three high level survey boreholes in the roof caving zone and the water conducted fracture zone were made in the 6206 fully mechanized top coal caving mining face in Wangzhuang Mine.A systematic survey and study were conducted.The heights of the roof falling and the water conducted fracture zone were obtained.An experiment formula to predict the max height of the water conducted fracture zone was obtained.The results showed that the water conducted fracture zone was abnormally developed under the condition of the fully mechanized top coal caving mining.The max height ratio slicing fully mechanized mining in the water conducted fracture zone under the same thick mining condition would be increased by 1.32,which would be 2.23 times larger than the conventional coal mining.The development mode would be in saddle form.Under the fully mechanized top coal caving mining,the fracture height and mining thickness rate would be 19.75 in average,could be closed to the fracture height and mining thickness rate under the initial mining condition of the conventional mining and slicing fully mechanized mining and would basically meet the development law of the initial mining water conducted fracture zone.