HR: 0830h
AN: NS41B-02    [Abstracts]
TI: Determining the State Properties in the Near-Surface Sands From a Seismic-CPT Integrated Model
AU: * Ghose, R
EM: r.ghose@citg.tudelft.nl
AF: Delft University of Technology, Department of Geotechnology, Mijnbouwstraat 120, Delft, 2628 RX Netherlands
AB: The relative density and the effective horizontal stress are two critical state properties that determine the deformation and failure behaviours of sandy soils. They are, therefore, important to the engineers. However, in-situ estimation of these two properties in shallow, unconsolidated sand deposits is at present virtually impossible. This leads to risks and accidents. To solve this problem, we propose a new idea of integrating two very different in-situ field measurements based on an understanding of the underlying physical models. We have addressed the models of seismic shear wave velocity and the cone tip resistance obtained by geotechnical cone penetration testing (CPT). Although these two indepenent field measurements correspond to very different levels of strain, for a given type of sand they depend primarily on the relative density (and hence porosity) and the effective horizontal stress. We have constrained the porosity-stress models of elastic shear modulus in unconsolidated soils using the field observed seismic shear-wave velocity. For modelling CPT, which is a direct push geotechnical measurement, we have used a cylindrical cavity expansion approach. The reliability of these models have been verified on field data. Finally, we have integrated these two models to obtain unique estimates of the relative density and the effective horizontal stress, which is not possible from either of the two masurements alone. When tested on actual field data, our approach appears promising.
DE: 5102 Acoustic properties
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly