PRACTICAL ASPECTS OF INSITU MEASUREMENTS OF MATERIAL DAMPING WITH THESEISMIC CONE PENETRATION TEST

The downhole seismic cone penetration test (SCPT) procedure has been e xtended to allow the measurement of material damping at small strains at minimum expense while one is measuring shear wave velocity. The nat ure of damping, the required equipment characteristics, and the recomm ended procedure and calculation methodology are presented in a practic al way. SCPT results from four different sites give results that are i n general agreement with laboratory measurements of damping for sands and clays and with values recommended by other authors. It appears, ho wever, that previously reported measurements of damping by borehole me thods are higher, by a factor of two or more, when compared with SCPT and laboratory results.