The characteristics of karst and deep coal mine karst water hazards in eastern North China

Focused on the problems of karst water hazard with mining depth,the paper discusses the concept of deep coal mining.The present mining depth reaches about 600 m and increases 12 m per year in key coal mines of eastern North China on the basis of on statistical information.Karst process and karst results of Ordovician lime-stone in eastern North China coal mine were analyzed from historical sedimentary environment and geological evaluation.The karst extent changed with the regularity of weak to strong to weak in vertical section and strong to weak along the same rock layer with depth in the coal mine region on the basis of observation and survey informa-tion.Some suggestions for deep coal mine water control are given.