Seismic Flat Dilatometer Tests in Connecticut Valley Varved Clay

Downhole shear wave velocity measurements have been incorporated within a “Marchetti” flat dilatometer by placing a velocity transducer in a connecting rod just above the blade. The hybrid of combining downhole seismic with flat dilatometer, termed the seismic dilatometer test (SDMT), has the superior advantages of determining both the routine estimates of soil properties and stratigraphic information, while also measuring the small-strain stiffness within a single sounding. The SDMT is rapid, simple, and cost effective, requiring essentially no more time than a conventional dilatometer sounding. Results of seismic dilatometer testing in clays at the National Geotechnical Experimental Test Site (NGES) in Amherst, Massachusetts are presented and compare favorably with results from companion series of seismic cone penetrometer tests.