Liquefaction characteristics of very loose Hostun RF sand in triaxial compression and extension

Undrained behaviour of very loose Hostun RF sand in triaxial compression and extension test is described. The samples are consolidated isotropically or anisotropically along constant effective stress ratio paths. The instability line of Lade is examinated in the case of extension test and extended for anisotropic samples. It is shown that monotonic and anisotropic consolidation strongly influences the instability concept. The steady state line is not unique in void ratio-log p′ space.