Stress distribution ahead of mechanized longwall top coal caving face with great cutting height

Abstract

Longwall Top Coal Caving (LTCC) technology with great cutting height is a new development trend in mining thick coal seam. The cutting height of LTCC face typically ranges from 2.8 m to 3.2 m in many coal mining countvies, but it recently reaches up to 4.2 m in many coal mines in China. Because the cutting height increases, the caving height accordingly decreases that changes the stress distribution around coal face and law of roof rock caving. Based on the geological condition of Longwall 4108 at Ping Shou coal mine, ShanXi province, China, this paper presents a modelling of LTCC mining process with a cutting height of 4.2 m by using the numerical program FLAC3D. From the modelling, the paper presents an analysis of stress distribution ahead of LTCC face with great cutting height. The results show that as the coal face advances, the stress magnitude ahead of coal face increases. The peak front abutment stress moves further away from coal face. The stress concentration ratio increases, and stress concentration zone expands correspondingly. These changes of stress facilitate the failure of top coal, increasing the efficiency of top coal recovery and improving longwall face stability.