焦作矿区薄基岩厚松散层工作面微震响应特征

Microseismic response characteristics of working face with thin bedrock and thick loose layer

为探究不同基岩厚度对薄基岩厚松散层工作面微震响应特征的影响,以焦作某矿14030工作面为例,依据基采比划分8.8~9.5,12.7~17.8两个阶段,对不同阶段的微震事件数量和能量的时空分布规律进行研究。结合工作面地质条件资料,阐明了工作面基岩厚度与微震活动特性的对应关系:微震事件呈现低位岩层聚集、高位岩层离散分布的特征;基岩厚度较小时,微震事件在基岩段均有分布,微震事件影响范围并未突破基岩顶界面;微震事件数量与每日推进距离近似成正比;随着基采比的增大,周期来压步距增加,基采比为12.7~17.8阶段较8.8~9.5阶段的周期来压步距增加了2.29m,底板破坏深度减少了35.2%,且日均微震事件数量在日均推进距离增加的条件下亦显著减少。研究成果可为分析厚松散层薄基岩矿井微震活动、覆岩破坏和矿压显现特征的相互关系提供参考。

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 are distributed 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.