Particle flow analysis on mechanized top-coal caving in steep thick seam

By using PFC^2D technique, the falling and moving process of top-coal and rock, and the flowing characteristics of loose medium in the process of top-coal caving in steep thick seam were analyzed for the horizontal and inclining compound working face arrangement of a coal mine by different recovering distances. The recovery of top-coal and the force characteristics of the powered supports for the top-coal caving working face by different caving sequences were discussed. The results showed that, firstly, the recovery of top-coal was high and the force characteristic of the powered supports for top-coal caving was good by adopting the top-to-down caving sequence. Secondly, the falling and moving configuration of loose medium was deflected toward the mined direction. Thirdly, the characteristic of lost coal in the process of top-coal caving was present with a particular rhythm. At last, the optimal caving distance was 1.2 m in all the conditions.