Research on development law and weakening effect of two zones in multi-coal seam mining

Xie Jian; Wang Daokun; Wang Tongming; Liu Mingzhang

doi:10.19896/j.cnki.mtkj.2025.05.004

Abstract：In the process of coal mining in our country,especially in the coal mining in western mining area,the phenomenon of repeated mining in multiple coal seams is a common occurrence.The development mechanism and law of water conducted zone in multi-seam mining are very complex,and the research on it is of great significance for the prevention and control of water damage in working face roof.Taking Changcheng No.5 Coal Mine in Etuokeqian Banner,Inner Mongolia as the research object,based on the analysis of its multi coal seam structure,a combination of empirical formula calculation and numerical simulation methods were used to calculate and analyze the height of mining induced fractures during individual and repeated mining of each layer.The research shows that the development law of mining-induced fractures in repeated mining is related to the spacing of coal seams,when the spacing is less than the height of the caving zone,repeated mining will lead to the increase of the overall guide height;when the overlying coal seam is located under the wa-ter conducted zone of the underlying coal seam,the repeated mining of the coal seam is the highest elevation of the two-layer guiding height;when the overlying coal seam is located above the water conducted zone of the underlying coal seam,the repeated mining of coal seam does not make the water conducted zone communicate with each other,but it still affects the formation and development of the frac-ture;in the case of repeated mining of multiple coal seams,the overburden roof has the phenomenon of"weakening",which leads to the decrease of the cumulative cracking and mining ratio after repeated mining of multiple coal seams.The research results have certain guiding significance for the prevention and control of water damage to the working face roof under repeated mining conditions.