Study On Mechanism And Control Technology Of Rib Spalling In Fully Mechanized Caving Face With Great Mining Height Of Three-soft Coal Seam

This paper takes the2141(3) working face in Panji No.1coal mine of Huainan mining group as the research background. Comprehensive used with theoretical analysis and computer numerical simulation to study the mechanism and control measures of rib spalling in fully mechanized giving face with great mining height of three-soft coal seam.Firstly, by using the D-P-Y criteria in rock plastic mechanics and the limit equilibrium theory, this paper have studied the width of plasticity area and the stress distribution characteristics which is in front of the coal wall, and their computational expressions was deduced successfully; what is more, the width of plasticity area have relations with a very kinds of factors, such as:mining height, mining depth, stress concentration factor, abutment pressure, internal friction angle and cohesion of coal mass, internal friction angle and cohesion of the interface between coal seam,and horizontal supporting force etc.Secondly, the mechanical model and the cusp catastrophic model was established. To treat the coal wall which is spalling as a cantilever beam fixed at base and bearing concentrated load at top, and a compression strut model fixed at base and free at top. Moreover, This paper is not only have analyzed the mechanism and the force situation of rib spalling, but also the maximum deflection and the maximum turning angle, and the necessary and sufficient conditions for rib spalling, and then the mechanism and process of rib spalling was described.What is more, according to the phenomenon of rib spalling of three-soft coal seam, six factors with significantly effect was selected, they are mining height, mining depth, supporting strength of hydraulic support, advance speed, horizontal supporting force with prevention board, coefficient of hardness of coal mass. The influence degree of rib spalling with them was analysed by numerical simulation software named FLAC3D, then the law of rib splling was probed, too.Finally, according to actual rib spalling of2141(3) working face in Panji No.1coal mine and based on the researches and analysis of previous chapters, several outstanding factors is summarized; at the same time, this article puts forward some of control measures for rib spalling.