Top coal failure mechanism and top coal falling control at front of fully mechanized longwall top coal caving mining face

With the site observation and the computer numerical simulation calculation method,the paper studied the top coal falling mechanism at the front of the fully mechanized longwall top coal caving mining face.The main affected factors of the top coal failing at the rear of the front face obtained were the distance of the front face,coal wall spalling area and the initial support force of the hydraulic powered support.The coal wall spalling control is the effective measure to control the top coal falling.The site application practices showed that the wooden bolting in the seam of the front face was an effective means to control the coal wall spalling.With the measures applied,the average coal and rock falling height was reduced from 3.5 m to 0.8 m and an obvious economic and technical benefit was obtained.