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Shallow, S-wave reflections over lagoon deposits
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 8th EEGS-ES Meeting, Sep 2002, cp-36-00125
- ISBN: 972-789-071-7
Abstract
The use of seismic shear (S) wave reflections to geotechnical characterization of the shallow subsoil has got a new meaning in the recent years with the availability of specialized hardware like the high-frequency shear-wave vibrator (Ghose et al., 1996), and new approaches for integration of seismic and geotechnical parameters (Ghose and Drijkoningen, 2000; Ghose and Goudswaard, 2001). The importance of S waves in geotechnical engineering is well-known. However, systematic correlation of S-wave reflections, indicating change in small-strain, elastic properties, to changes in large-strain, failure or strength properties of the soil is a recent observation. The correlation of S-wave reflections to changes in CPT (Cone Penetration Test) cone resistance has been found at common soil sites composed primarily of sand, clay and peat layers (Ghose et al., 1996; Ghose and Goudswaard, 2000; Brouwer et al., 1996, 1997; Goudswaard and Ghose, 2001). Recently, in relation to planned engineering constructions on landfills overlying non-tropical lagoon deposits, we have carried out shallow seismic reflection experiments, and investigated the correlation between S-wave reflections and CPT data. S-wave reflectivity information for the mud-silt and mud-sand interfaces, typical for lagoon deposits, was unknown. The objective of our research, directly related to practical engineering needs, was two-fold: (1) to check the potential of shear wave reflections for laterally continuous delineation of the subsoil boundaries in a lagoon deposit, and (2) to verify the correlation of S-wave reflections with CPT cone resistance.