On the condition that the kinetic energy of coal shell in premonitory phase of its outburst is ignored; the equilibrium equation of spherical symmetric force of pore medium is established

which is under the coupling action of ground stages

gas pressure and effluent seepage. The character of spherical symmetry makes the strain Lode parameter at elastic and plastic stages is the same

and meet the condition of the physical relation of single curve. Popularized the uniaxial constitutive model

it can be educed that the relational expression between stress intensity and strain intensity of coal shell. It is discovered that

the educed expression of radial displacement u in elastic and plastic zones of coal shell

can be broken down into the displacement corresponding to deviatoric strain and the displacement corresponding to average strain. The energy analysis

which is carried through by using geometry equation

force equilibrium equation

physical equation and the relation of stress intensity and average stress synthetically

shows that the external force work change can be broken down into the external force work

and corresponding to deviatoric stress

mean stress and seepage stress; they are respectively corresponding to changes of strain energy of deviatoric stress

volumetric strain energy and pore volume energy; i.e.

. and The findings of two work-energy increment equilibrium relationship can be educed. It builds up the foundation for engaging catastrophe theory analysis of disintegration and outburst of a single coal shell in the outburst process.