Abstract: The bender element is an important common equipment in the soil test laboratory, which is often used to test soil shear wave velocity. Although the bender element has the capability of measuring the longitudinal wave velocity (P wave), its application is still rarely reported. With a better understanding of the unsaturated soil, the importance of P wave property is increasing. In this paper, the behavior of the bender element system in measuring the coral sand samples is evaluated. The relationship between P wave velocity and physical parameters of coral sand is also studied. The results show that there is a good positive correlation between the magnitude of wave velocity and the confining pressure, and the growth trend of wave velocity value slows down with the increase of pressure. The water content has a great influence on the wave velocity, and it is a quadratic function. At the same time, the wave propagation in the saturated soil is very different from that in the unsaturated soil, and the typical characteristics of the wave propagation in two-phase saturated media can be observed.

Key words: Bender Element, Coral Sand, P-Wave