Research on the sudden changes and the controlling factors of deep coal mining conditions

<正> It was illustrated that the mining conditions inducing disasters changed with depth both in regularity of gradual and sudden change.The sudden change depth for different disaster conditions are different and controlled by different factors.The high temperature and its change with depth are mainly controlled by strata structures and rock heat conductiv- ity property,the high rock stress and dynamical engineering disasters and their change with depth are mainly controlled by tectonic conditions,roof strata rock property and deep rock mechanical property,coal mine water disasters and their change with depth are mainly con- trolled by rock mechanical property of coal seam floor and regional groundwater circulation conditions,gas disaster conditions and their change with depth are mainly controlled by buried conditions of coal seam and opening conditions of geological structures.It is men- tioned that the key point for the control of deep coal mining disaster is to clearly understand the sudden change depth of different factors causing disasters.