Stress-displacement-microstructure characteristics and constitutive modelling of sand-structure interfaces
The microstructure of sand-structure interface would evolve due to resulting in the state dependence of its stress-displacement behavior.A series of monotonic and cyclic interface direct shear tests on the sand-steel interface under constant normal stiffness(CNS)and constant normal load(CNL)conditions were carried out,where the evolution of the microstructure within the interface was analyzed using high-resolution image identification technique.It was found that different extents of interface dilatancy occurred under monotonic tests with CNS and CNL.Higher extent of dilatancy and microstructure evolution took place under CNL,where the particle probabilistic entropy increased with the shear displacement.When subjected to cyclic shearing,the interface with initial state under the critical state line exhibited contraction and dilatancy alternately.As the load cycles increased,the microstructure within the interface evolved,with an alternately increase or decrease in the particle probabilistic entropy,which resulted in an overall contraction of the interface.Thus,microstructure evolution influences the interface dilatancy.To capture these phenomena,a microstructure-dependent dilatancy state line was proposed,based on which a nonassociated kinematic hardening elastoplastic model for sand-structure interface was developed.The model had 12 parameters,which can be all determined from laboratory test.Simulations of the test data revealed that the model can reasonably capture the dilatancy and softening behaviors,etc.,of the interface,especially the strong contraction behavior under cyclic loads.
soil mechanicsinterfacemicrostructuredilatancystate parameterconstitutive model
NETL
NSTL
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