Preliminary results of P-wave and S-wave measurements by seismic dilatometer test (SPDMT) in Mirandola (Italy)

A trial seismic dilatometer-VP (SPDMT) has been recently developed to measure the compressional wave velocity VP, in addition to the shear wave velocity VS and to the DMT geotechnical parameters. The new SPDMT is the combination of the traditional mechanical flat dilatometer (DMT) with an appropriate seismic module placed above the DMT blade. The SPDMT module consist in a probe outfitted with two receivers for measuring the P-wave velocity, along with two receivers for measuring the S-wave velocity. The paper describes the SPDMT equipment, the test procedure and the interpretation of VP and VS measurements, together with some considerations on the potential geotechnical applications which can benefit from the contemporary measurement of the two propagation velocities. Finally, the paper illustrates preliminary results of P-wave and S-wave measurements by SPDMT compared to several cross-hole, down-hole and suspension logging data at the Mirandola test site (Italy), a soft alluvial site which was investigated within the InterPACIFIC (Intercomparison of methods for site parameter and velocity profile characterization) project.