Numerical simulation of the top coal caving process using the discrete element method

How to understand the top coal caving process and increase the top coal recovery ratio is one of the urgent problems to resolve for long wall top coal caving technology. This paper discusses a new theory and technology of top coal caving with vibration. The vibration device is mounted on the shield beam of the top coal caving support. The vibrator destroys the arch structure formed during the top coal caving process, which results in the smooth top coal caving process, and in this way the top coal recovery ratio is increased. The distinct element method(DEM) numericals of software particle. flow code in 2 dimensions (PFC2D) is used for the numerical simulation. It is proven that the vibration can easily destroy the arch structure which is formed during the top coal caving process. The parameters about when the arch structure would be formed during the top coal caving process have been obtained. The movement of the top coal caving process under the vibration condition makes a more stable layer uniform caving performance. The aim of the top coal caving with vibration technology, to increase the top coal recovery ratio and to lower the waste content rate, has been achieved. (C) 2009 Elsevier Ltd. All rights reserved.