To explore the influence of different bedrock thicknesses on the microseismic response characteristics of thin bedrock and thick loose layer working faces. The 14030 working face of a mine in Jiaozuo is taken as an example with different thickness of the bedrock area. According to the ratio of bedrock thickness to mining height,two stages of 8.8-9.5 and 12.7-17.8 are divided,and the spatio-temporal distribution of microseismic event frequency and energy in different stages are studied. Combined with the geological conditions of working face,the corresponding relationship between the bedrock thickness and the characteristics of microseismic activity is obtained:The microseismic events show an accumulation characteristic in low overlying strata,but a discrete distribution characteristic in high overlying strata. When the thickness of the bedrock is small,microseismic events aredistributed throughout the bedrock section,but does not exceed the top bedrock interface. The number of microseismic events is approximately proportional to the daily advance length. As the ratio of bedrock thickness and mining height increases,the pressure step distance between the ratio of bedrock thickness to mining height of 12.7-17.8 stage and 8.8-9.5 stage increases by 2.29 m,and the failure depth of floor decreases by 35.2%. Moreover,the number of daily microseismic events also significantly decreases with the increase of daily advance length. The research provides a reference for analyzing the relationship between microseismic activity,overburden failure and rock pressure in thin bedrock mine with thick loose layer.
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