EMPIRICAL CORRELATION BETWEEN THE SHEAR-WAVE VELOCITY AND THE DYNAMIC PROBING HAVY TEST: CASE STUDY, VARAZDIN, CROATIA

Varazdin is located in the north-western part of Croatia in shallow quaternary alluvial sediments of the Drava River basin. Local site effects due to the alluvial soft sediments can play a crucial role in the amplification of seismic-wave ground motions. The shear-wave velocity (V-S) is one of the most important parameters for determining dynamic soil properties and ground-response analyses. The seismic surface wave method (MASW) is the simplest and a very efficient way of measuring the shear-wave velocity in the field. The Dynamic Probing Heavy (DPH) test is suited to determining the soil strength and the soil deformation properties. However, there are a lack of correlations between the shear-wave velocity and the DPH tests (V-S - N-DPH) in the literature. In this paper we present empirical correlations between the shear-wave velocity V-S and the soil penetration resistance N-DPH with: a) raw (original) N-DPH data: V-S = 97.839. N-DPH (0.395), (R-2 = 0.723); b) a groundwater correction N-DPH data: V-S = 92.998.N-DPH (0.363) (R-2 = 0.815). From the measured DPH data, the shear-wave velocity (V-S), the shear modulus (Go) and the Young's modulus (Eo and Er) were estimated. Two different approaches (low V-S. high strain) were compared, and the results were found to be in good agreement when the relative difference between the velocities is small and smooth. Dynamic probing tests are good for studying a discrete point of interest in a large field area based on preliminary seismic tests. The suggested correlation V-S-N-DPH can be used for a rough estimation of V-S from N-DPH (they are site-specific, and so not applicable worldwide). In this way valuable information about dynamic soil properties can be extracted for ground-response analyses and the study of local site effects.