Parametric Gmax sounding of granular soils by vibration methods

To solicit a fundamental understanding of past difficulties of vibration sounding methods for granular soils, a collaborative experimental and analytical study was developed to examine the performance of dynamic surface plate load tests by scaled modelling. Focused on the benchmark small-strain regime and Gmax condition, multiple small-amplitude vibration tests on a rigid square plate resting on a uniform dry sand were conducted on a large geotechnical centrifuge. A set of basic experimental results on the vertical and rocking dynamic characteristics of the soil–plate system were generated by means of a new eccentric test format, as well as by conventional symmetrical vertical vibration. Through a comparison of the measured data with canonical continuum solutions of a half-space with constant as well as common depth-dependent shear modulus profiles, some fundamental issues in regard to the relevance of such commonly accepted idealisations of the intended practical application were revealed. As an experimental way to confirm and circumvent a key aspect of the problem, the novel test strategy of using a lightweight foundation in an embedded configuration was proposed and evaluated.