SEISMIC FLAT DILATOMETER TESTS IN CONNECTICUT VALLEY VARVED CLAY

Downhole shear wave velocity measurements have been incorporated withi n a ''Marchetti'' flat dilatometer by placing a velocity transducer in a connecting rod just above the blade. The hybrid of combining downho le seismic with flat dilatometer, termed the seismic dilatometer test (SDMT), has the superior advantages of determining both the routine es timates of soil properties and stratigraphic information, while also m easuring the small-strain stiffness within a single sounding. The SDMT is rapid, simple, and cost effective, requiring essentially no more t ime than a conventional dilatometer sounding. Results of seismic dilat ometer testing in clays at the National Geotechnical Experimental Test Site (NGES) in Amherst, Massachusetts are presented and compare favor ably with results from companion series of seismic cone penetrometer t ests.