ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pAO9. Using shear waves to predict the liquefaction potential of seafloor sediments.

James Pyrah

Angela Davis

School of Ocean Sci., Univ. College of North Wales, Menai Bridge, Gwynedd LL59 5EY, UK

There is growing evidence to support the use of the seismic shear wave velocity as a predictor of seafloor sediment liquefaction potential. At the University College of North Wales laboratory experiments are being performed to determine the steady-state characteristics of a variety of noncohesive sediments. The conventional laboratory approach involves an investigation of void ratio/effective stress relationships, and provides an indication of the sediment's likely behavior---contractive or dilative---when subjected to cyclic shear stresses such as those imposed by earthquake or water wave loading. In the tests currently being carried out at UCNW, the shear wave velocity is also being monitored to establish velocity/void ratio/effective stress relations which offers the possibility of extrapolating the laboratory findings to the field situation. Thus given a knowledge of the in situ shear wave velocity, grain characteristics, and static stress regime, it becomes possible to provide an estimate of the sediment's stability under cyclic load conditions.