Abstract: A lot of residual coal pillars of irregular blocks coal resources were left after longwall mining. These coal resources are mainly exploited by the short-wall mechanized block mining technology, using continuous miner. Whether the section coal pillar is stable or not is the key to safety of irregular blocks coal mining. According to the geological production conditions of the 2-2 seam in Datong Coal Mine Group，catastrophe theory has been applied to analyze the catastrophe instability mechanism of section coal pillars. The essential condition for catastrophe instability of section coal pillars has been derived: when plastic zone width of coal pillar is more than 86%. The numerical simulation results will conform to the observations. The dynamic evolution process of failure in section coal pillars and stope has been simulated . Taking the section coal pillar in Datong Coal Mine as an example, the theoretical calculation results for catastrophe instability is that plastic zone width of coal pillar should be no more than 12.9 m, which is consistent with drilling peep experimental results.

Key words: block mining method, section coal pillars, catastrophe theory, coal pillar stability, numerical simulation