Coupling relation between damage-induced permeability evolution and accelerated creep deformation of volcanic breccias

Following the previous work about the relation between permeability evolution and rock creep deformation [1-2], triaxial creep tests of volcanic breccias under various seepage pressures were performed on rock specimens and their lateral deformation behavior in the accelerated creep phase volcanic breccias were also studied. Creep damage variable and related evolution equation in accelerated creep were proposed. Based on the relation of damage variable associated with lateral creep strain, the correlativity between axial permeability coefficient and lateral damage-induced strain under different confining pressures was analyzed, and then the relation equation of permeability coefficient as a function of damage-induced strain during the process of accelerated creep was obtained. An assumption was made that the axial permeability coefficient has close relationship not only with lateral creep strain, but also with creep damage-induced crack growth. The equation can be applied for for numerical analysis of coupling seepage and stress during the process of rock creep damage.