Deformation dependencies of sand stiffness

To model disturbed sand stiffness, it is necessary to combine drained and undrained response, loss and recovery of sand stiffness, during irregular loading sequence. Such solution is necessary for designing offshore wind turbine foundations and predicting soil behavior during (and after) seismic events. To gain deeper understanding of fundamental phenomenon governing disturbed sand behavior, unconventional testing procedures were attempted using a frictionless triaxial apparatus. The resulting observations reveal a new physical phenomenon (deformation dependent stiffness hysteresis loops). The new observations are then used to derive an unconventional model (BSM), which uses a strain (deformation) envelope.