Exploring Non-gravity Geotechnics Triaxial Compression Tests in Zero-Gravity Environment

The recent demand for performance-based seismic design of geotechnical structures requires knowledge about residual deformation of soils subjected to cyclic loading. This chapter concerns deformation characteristics of liquefied sand that may deform to a strain of 100% or more during and after strong ground shaking. To evaluate the liquefaction-induced ground deformation thus produced, it is essential to understand and validate the deformation characteristics of sand under very low effective stress. In this respect, a new type of triaxial shear test has been developed in which the effective stress is made extremely low by making the gravity effects very small. In other words, triaxial shear tests were conducted in a freefall capsule to achieve a state of null effective stress. It was shown that sand deforms in a viscous manner under constant load when effective stress has disappeared. The obtained coefficient of viscosity was then made use of to run deformation analyses on a geotechnical structures resting on liquefied sand.