Density and undrained shear strength of bed sediment from ND-CPT

Abstract

The density and the undrained shear strength (s u) of bed sediments at either side of the Isahaya Bay dike in the Ariake Sea, Japan, were investigated using nuclear density cone penetration tests (ND-CPTs). The nuclear density cone penetrometer (ND-CP) was operated from a boat, conducting 71 ND-CPTs. Furthermore, 26 undisturbed samples were obtained for soil density and s u measurements to calibrate the ND-CPT data. The results show that the density and s u obtained from in situ with the ND-CPTs agree well with those from the laboratory tests on undisturbed samples, and the obtained density profiles show good repeatability. The vertical variation in density and s u of the bed sediment can be obtained from the ND-CPT results. The relations between the density and s u show that s u increases with an increase in density, but that this relation is site specific. The values of s u show an exponentially growing trend and the values of log s u show a linearly increasing trend with density. The vertical distribution of the bed sediments can be described using the density values obtained with the ND-CPT.