Water Infiltration into Rock observed by P Wave Velocity and Amplitude Ratio

Abstract

To characterize water infiltration into dry cracks, P wave velocity and amplitude ratio in various directions of Yamaguchi fine grained marble were measured under true triaxial creep stress state where three principal stresses in specimen were kept constant during experiment. All waves traveled in a direction parallel to the axis of minimum principal stress. Water was infiltrated from the bottom of specimen through porous metal and end piece soon after true triaxial creep stress was held constant.
When the stress-induced microcracks in a rock are filled with permeating water, P wave velocity increased with time and amplitude ratio for first and second peaks of P waves are also influenced depending on the degree of the saturation of water. In each measuring path, amplitude ratio is observed to increase prior to increasing P wave velocity.