Research and practice on pressure control of sub-level longwall face surrounded by mined areas

According to the field observation and theoretical research,the overlying strata structure and mining pressure control techniques for sub-level longwall face surrounded by mined areas were presented.The key theoretical problem was how to consider the relationship between strata spatial structure and mining pressure field.The key techniques are as follows: juding fracturing forms of coal pillar based on pressure monitoring in drilling hole;constructing another safe roadway near the maingate and tailgate;expanding entries;injecting new materials into surrounding coal for consolidating coal and sealing methane.The mining practice of sub-level longwall face in Yima Coal Mine of Henan Province was introduced.These techniques could be used in coal mines with similar condition.