Research On Permeability Characteristic Of Porous Media Of Pellets Packing

Considering the porous media is deformable, so the pore structure and the pore volume will change under the outer stress. It leads to a changeful permeability according to pore volume. Under this condition ,the linear Darcy Law is not valid when the seepage profile is studied. We must retrofit the linear Darcy Law.In this paper, the manual porous test piece is studied under the conventional three triaxial pressure. Through the experiment, the seepage velocity is obtained with the varied pressure head. Then the permeability can be derived from the Darcy Law. At the same time, the curve about velocity, permeability and hydraulic gradient could be received. After that, a serial of velocities and permeability can be met by changing axial and side stress. At last the curve about permeability and volume stress can be get through fitting. The fitting function is a negative power function. This shows that the seepage velocity and the hydraulic gradient is not satisfied the linear relation when then hydraulic gradient is very small. The linear relation will be more obvious with the heighten of the hydraulic gradient.The consolidation test without draining under normal three axial stress is also studied in this paper. The sample clotted deformation is recorded with different pore hydraulic pressure. It is found that the clotted deformation and the pore pressure is not fitting linear relation, and the pore pressure coefficient should be the function of pore pressure and volume stress in the law of effective stress.At last, the pore pressure in the double porous media coupled with pore deformation is studied. The physical model and physical model are both founded, also the control equations and boundary conditions, the solvable problem is formed. On this ground, the small pellets pore pressure P₁ and the bigger pellets pore pressure P₂ can be got in the double pore media by volume control numerical technique. Then through changing parameters, the pore pressure profile had been received under different pellet diameter pore volume and time. It has been found that the parameters about bigger pellets have more obvious influence on the profile of P₁ and P₂ than that of small pellets. It is just contrary when it comes to the pore pressure. The pore volume will effect the pore pressure and the bigger the pore volume, the bigger the pressure P₁ to P₂. When the time is long enough, the pressure P₁ and P₂ will be equal, also their pressure gradient will be constant.