Dynamically and statically measured small strain stiffness of dense Toyoura sand

Small strain stiffness of dense Toyoura sand was investigated by performing triaxial compression tests using large scale apparatus. The specimens were rectangular prismatic with dimensions of 50 cm high and 23.5 cm times 23.5 cm in cross-section. To measure the vertical stress a 1, a load cell is located just above the top cap inside the triaxial cell in order to eliminate the effects of piston friction. The vertical strain E I was measured not only externally but also locally with three pairs of vertical local deformation transducers (LDTs). Three tests were conducted using air-dried Toyoura sand (D-max = 0.35 mm, D-50 = 0.23 mm, U, = 1.80, e(max) = 0.966, e(min) = 0.600 and G(s) = 2.635) as the test material. The specimens were prepared by employing air pluviation method and keeping dry densities within the range of 1.62 - 1.63 g/cm(3). Dynamic and static Young's moduli were evaluated by wave velocity measurement and by conducting small unloading / reloading cycles, respectively.