Site Analysis for Seismic Soil Liquefaction Potential

Field penetration data and cyclic laboratory test data are presented for evaluating the seismically induced soil liquefaction potential at a waterfront site. Dynamic split-spoon penetration recordings and three types of quasistatic friction cone probings were made. The friction cones were the standard mechanical cone, the electric cone, and the piezometric cone. The latter penetrometer has a porous element near the tip which permits measurement of pore water pressures generated during penetration. By interrupting penetration, the rate of pore pressure dissipation can be recorded, so an estimate of soil permeability can also be derived. Undisturbed samples were taken using an Osterberg piston sampler, and the specimens were subjected to cyclic triaxial testing in the laboratory. The field sounding techniques were in agreement; however, they indicated a recently deposited sensitive silty sand to have a liquefaction resistance approximately one-half that based upon cyclic triaxial testing. The question arises as to whether the liquefaction resistance as determined by laboratory testing is more appropriate herein, or whether behavior suggested by the penetration test results more realistically predicts the response of this type of soil to an actual earthquake