Prediction of cone penetration resistance and its application to liquefaction assessment

The need to assess the liquefaction potential of sandy soil deposits is crucial to the safe and economical design of many civil engineering projects. While the cone penetration test (CPT) has been adopted worldwide as an economical and efficient in-situ test for many site investigations and types of geotechnical design, few data are available at the present time to enable development of a direct correlation between cone resistance and liquefaction resistance. The main objective of this study, therefore, was to derive such a correlation. This correlation is based on the assumption that the factors that increase the liquefaction resistance of a given soil also increase the cone resistance.; A cone resistance prediction method based on the cavity expansion theory was developed. In order to account for nonlinear soil deformation behavior and the limited sample sizes used in calibration chamber tests, some modifications were made to the cavity expansion method proposed by Keaveny (1985). The modifications included: (1) solution was made for a finite soil mass, (2) the soil outside the plastic sheared zone around the cone tip was assumed to be nonlinearly elastic, and (3) the shape of the expanding cavity created by the penetrometer was assumed to be a combination of sphere and cylinder. Thus the ultimate pressure required for expanding a cavity was assumed to be an average value of the pressures to expand a spherical cavity and cylindrical cavity in the soil mass. A numerical scheme was adopted to compute the ultimate cavity expansion pressure iteratively, and a finite element program was written to serve this purpose. Chamber cone penetration test results were used to validate cone resistance prediction method for four different sands, namely, Monterey #0 sand, Ticino sand, Hokksund sand, and Sacramento River sand.; A direct correlation between the predicted cone resistances and liquefaction resistance was derived from the results of cyclic load tests on the same sands. Available field data were used to examine the consistency of the proposed correlation.; The in-situ horizontal stress is as important as the vertical stress for the development of cone penetration resistance. Thus, a parallel effort was carried out during this research program to improve our ability to measure the in-situ horizontal stress. The design of a lateral stress sensing cone penetrometer developed by Huntsman (1985) at the University of California, Berkeley was modified to improve its durability for field tests. A limited number of chamber tests with this new penetrometer have given good results.