Permeability characteristics experiment and its mechanism analysis of two types of rocks

To study the different permeability characteristics of rock, transient permeability tests of limestone and diorite were carried out. The permeability evolution and the relation between pore pressure and time of rock specimens during the complete stress-strain course were investigated. The strain-permeability equations of rock specimens during the deformation and failure course were set up. Finally, the penetration mechanism of two types of rocks was analyzed. The result shows that the phenomenon of the sudden jump of permeability occurs at the peak strength and keeps very low unchanged permeability before the peak strength for diorite. But limestone's permeability gradually increases with increasing deformation before and after the peak strength. The fitted equations for the strain-permeability curve more deeply describe the permeability characteristics in compressive failure. The relation between pore pressure and time is quartic polynomial with one unknown. The rock permeability has relations with the stress state and the internal structure and the mechanical properties of rock.