Various information on SDMT testing procedure, is contained in the general description page of the SDMT equipment.
Additional information can be found in SDMT Specifications(en/ita).
In order to execute a seismic test (by SDMT), the membrane has to be closed, for completeness of the electrical circuit. Therefore, if the soil pressure is insufficient to close the membrane, the operator should apply a depression during the SDMT execution.
Butcher A.P., Campanella R.G., Kaynia A.M., Massarsch K.R. (2005). “Seismic cone downhole procedure to measure shear wave velocity – a guideline“.
ASTM 2008 “Standard Test Methods for Downhole Seismic Testing“.
Protezione Civile (2008) “Indirizzi e criteri per la microzonazione sismica” Università di L’Aquila, Dipartimento DISAT, Prova SDMT pp. 397-405.
SEISMIC SOURCE ONLAND AND OFFSHORE
Correct hitting direction: should be (at least approximately) perpendicular to the line from the rods to the center of the source.
SEISMIC SOURCE ONLAND
SEISMIC SOURCE OFFSHORE
SDMT seismic measurements are possible also in offshore sites. A modified version of the shear wave source is lowered to the seafloor and is actioned from the operator at surface. Measurements of Vs have been performed with a maximum water level of 50 m and at a maximum depth of 40 m below the seafloor.