Keynote lecture: Frequency characteristics of stress wave and penetration during SPT

Recently wave equation analysis has been successfully applied to the SPT to determine the energy transfer ratio for adjusting the N-value, but should not limited to this purpose. The SPT N-value has been applied to the design of foundations for more than 50 years, however, the correlation between the N-value and the design parameters have been estimated crudely based on experience, so that new methods or constitutive equations should be established for determining the design parameters rationally. The frequency characteristics of the stress wave and the behaviour of the penetration of the rod system are introduced, because the relation between them could be keys to further studies.