perfect state
5.Due to the fact that China lacks special legislation on state resources security and the existing laws and regulations of protecting natural resources cannot satisfy the demands of state resources security under the principle of the sustainable development, it is essential to establish and perfect the state resources security law protection system.
6.Viewed goaf gas as no-glutinosity compressible gas, and the goaf gas flow as adiabatic flow at the perfect gas state, based on the continuous equation, movement differential equation, energy equation, finally got the velocity of shock gas which was produced by the instantaneous fall large area roof in goaf, and the frictional resistance that shock gas bearing when it flowing in the entry.

