9712852 Benoit This project addresses the evaluation of a novel field technique to be used at the Treasure Island National Geotechnical Experimentation Site (NGES) in San Francisco, California; the objective being to evaluate the insitu void ratio and soil fabric at this site. This technique consists of vertical and horizontal measurements of soil electrical resistivity using two specially instrumented piezocones simultaneously pushed into the ground. The method, designed by a research group in Italy at the Hydraulic and Structural Research Center of the Italian Electricity Agency (ENEL-CRIS), allows continuous electrical resistivity measurements in the vertical direction for each probe and in the horizontal direction between the two probes. The results, using groundwater and soil samples, are calibrated against laboratory tests on samples reconstituted at various densities. This field technique permits a large volume of soil to be tested, avoiding the unwanted remolding effects surrounding the device. Because of the difficulty in obtaining undisturbed insitu samples for laboratory testing of sands, this insitu method shows great potential in providing parameters needed for the prediction of the dynamic response of soils subjected to earthquake loading. The potential of this insitu electrical resistivity cone penetration test to provide new soil parameters to evaluate the earthquake response of natural sand deposits will advance the state-of-the-art and permit rapid and cost- effective methods for characterization of cohesionless soils.
