Study on Height of Water Flow Crack Zone in Fully Mechanized Top Coal Caving Mining Face in Approximate Horizontal Seam

In order to study a height of a water flow crack zone in a fully mechanized top coal caving mining in a approximate horizontal seam,a material mechanics was applied to the study on the formation mechanism of the water flow crack. A theoretical calculation,discrete element numerical simulation software UDEC and site observation methods were applied to the calculation of the water flow crack distribution scope in No. 8100 coal mining face of Tongxin Mine. The results showed that a coordination of the strata subsidence value and the span of the rock strata would be decisive factors of the crack channel formed. An experience formula of a slicing mining water flow crack zone would be suitable to the fully mechanized top coal caving mining and the numerical simulation would be an effective method to calculate a height of the water flow crack zone in the fully mechanized top coal caving mining.