Dynamic Instability of Cohesionless Soils:
Forms of Occurrence and Main Regularities

E. A. Voznesenskii

Moscow State University, Vorob’evy gory, Moscow, 119899 Russia

Received January 13, 1997

Abstract—Possible variants of soil behavior, represented in terms of liquefaction, cyclic mobility, and dynamic
stability, are considered on the basis of triaxial dynamic tests of dry and saturated sands. The determining role
of the degree of stress sign inversion, numerically characterized by a reduced coefficient of cycle asymmetry,
is demonstrated. It is shown that saturated sand becomes unliquefiable only when a consolidation degree is
higher than 70–80%, and that cyclic mobility is the most universal type of sand dynamic instability (in cases
of both positive and negative dilatancy). This instability may be observed under any loading condition or
arbitrary degree of soil consolidation, and it can result in soil failure at a relative pore pressure that is higher
than critical (0.7).