Volume 31, Issue 1 (January 2008)
A Suction-Control Apparatus for the Measurement of P and S-wave Velocity in Soils
This paper presents a new apparatus for the measurement of P and S-wave velocities in unsaturated soil specimens under controlled net stress and matric suction conditions. The system consists of a triaxial cell modified to enable an independent control of the pore air and water pressures as well as the confining pressure, and to accommodate P and S-wave sources and receivers. The system also includes three servo-controlled pressure pumps, and a computer control system that drives the pressures and acquires volume changes. Three sets of experiments were conducted to verify the system performance. Specific matric suction values were applied while monitoring the stabilization process of capillary pressures using the P and S-wave velocity measurements. Both P and S-wave velocities increase due to the rise in interparticle forces resulting from the increase in matric suction.