MECHANICAL PROPERTIES OF UNDISTURBED TONE-RIVER GRAVEL OBTAINED BY IN-SITU FREEZING METHOD

Abstract

Undisturbed samples of gravel deposit were obtained from alluvial deposits by an in-situ freezing method, and their mechanical properties were determined based on laboratory tests. The samples are considered to retain high quality, based on the fact that shear wave velocities measured both in the field and the laboratory showed good agreement. The laboratory tests were also conducted on specimens reconstituted to the density of the undisturbed samples. It was found that : (1) the undrained cyclic shear strength of the undisturbed gravels are considerably higher than those of the reconstituted ones : (2) the shear moduli of the undisturbed specimens are about 20% higher than those of the reconstituted ones, but relationships between normalized shear modulus G/G₀ and shear strain are almost the same between the two : and (3) the internal friction angles of all the specimens tested are almost the same at about 40°.