Sediment shear waves: a comparison of in situ and laboratory measurements
Abstract
Surficial sediment shear wave velocity measurements were made at eight sites (water depths 7-22 m) in the vicinity of La Spezia, Italy. Values of shear wave velocity measured in situ ranged from 16 m/s in flocculent clays to 90 m/s in hard-packed sands. Values of laboratory measured shear wave velocity were 6-22 m/s lower from the same sites. Low variability of measured shear wave velocities allowed laboratory measurements to be corrected to in situ conditions using the following empirical relationship: Vs, (in situ) = 10.46+1.17 Vs, (lab) The most likely causes for the lower laboratory shear wave velocities were sediment disturbance during collection, transportation, storage and measurement both by mechanical manipulations and by changes in confining pressure. Sediment porosity, void ratio or wet density can be used to predict in situ shear wave velocity. Further studies are required to refine and extend these empirical relationships, and to accurately define the high gradients in shear wave velocity predicted for the upper few meters or sediment.
Report Number
SM-210Date
1989/03Author(s)
Richardson, Michael D.
; Muzi, Enrico
; Troiano, Luigi
; Miaschi, Bruno