Abstract: Permeable experiments on porous media of pellets packing under the condition of constant confining pressure,constant axial pressure and different pore pressure were carried out in a type SLB-1 triaxial compression apparatus.In consideration of the character that permeability of poroelastic media varies with its deformation,a nonlinear mathematical model of permeability coefficient is established.The research result shows that the seepage process consists of unstable and stable seepage stages.The permeability coefficient takes on the nonlinear characteristic,gradually close to linear with the decrease of the axial pressure and confining pressure.The thory deduce of one dimensional steady seepage problem illustrates that gradient of pore pressure in the testing sample is non-homogeneous.On the basis of the experimental data,parameters of theory model of permeability coefficient are determined by using least-squares.The permeability coefficient calculated by the nonlinear mathematical model is around 2.5 times as that by the Darcy law.

Key words: Particle, Porous media, Nonlinear seepage, Pore prssure