Researchers at the geotechnical laboratory at the university of new hampshire have developed a technique for measuring shear (s) andcompression (p) wave parameters of triaxial specimens. The triaxialend caps contain s and p wave transducers. Bender bimorphs are usedfor s waves and thickness expanders are used for p waves. These piezoelectric devices are separated from the triaxial specimen by a flexible window, which protects the transducers from failure due to moisture and allows proper coupling of the acoustic energy. Testing to date has focused on two areas. The first is determining the relationship between the acoustic characteristics of sand and liquefaction resistance. Results indicate that material-dependent one-to-one relationships can be established between s or p wave velocity and liquefaction resistance. Preliminary results from frequency domain measurements related to damping are encouraging as an indicator of sand fabric. The second area is the relationship between shear strength and sor p wave velocity in clays. Staged tests on marine clays indicate the effects of stress history and plasticity on this relationship. This paper appears in transportation research record no. 1309, Geotechnical engineering 1991.
Samenvatting