In situ determination of Ghh at Bothkennar using a novel seismic method

The paper describes a novel seismic method for determining the variation of velocity with depth of horizontally propagating, horizontally polarized shear waves (S-h,S-h). The technique exploits the curved paths of seismic waves in deposits with increasing velocity properties with depth. The new method has been applied at the soft clay test site at Bothkennar, and the results of this survey are compared with S-h,S-h and S-v,S-h wave velocity profiles obtained using conventional crosshole survey techniques at the site. The seismic data are further compared with the results of recently reported bender element tests on unconfined samples from the bedded and mottled Bothkennar clay. It is shown that, at the site investigated, the new method presents results comparable to those from the established field survey techniques. Neither the seismic nor the bender element data indicate significant stiffness anisotropy at the site.