Abstract: To facilitate the analysis, room-pillar system is simplified into a built-in beam-pillar mechanical system and its mechanical model is established.According to the constitutive relation of mechanical system, the cusp catastrophe theoretical mode is built.It is shown through analysis that the instability of pillar is only dependent on its internal conditions and independent of the external function.The energy release mechanism of the pillar sudden instability is also studied, which indicates that the energy release due to instability is also only related to the room-pillar system itself.The conclusion is finally drawn that to rationally optimize the mechanical-geometrical property parameters of the room-pillar system itself so as to destruct the necessary conditions for the pillar sudden instability is the effective means to control the pillar stability so as to ensure a safety production.

Key words: Built-in beam-pillar, Cusp catastrophe theory, Collection of branches, Energy release mechanism