.. function:: nDMaterial('CycLiqCPSP', matTag, G0, kappa, h, M, dre1, dre2, rdr, alpha, dir, lambdac, ksi, e0, np, nd, ein, rho)
:noindex:
This command is used to construct a multi-dimensional material object that that follows the constitutive behavior of a cyclic elastoplasticity model for large post- liquefaction deformation.
CycLiqCPSP material is a constitutive model for sand with special considerations for cyclic behaviour and accumulation of large post-liquefaction shear deformation, and is implemented using a cutting plane algorithm. The model: (1) achieves the simulation of post-liquefaction shear deformation based on its physics, allowing the unified description of pre- and post-liquefaction behavior of sand; (2) directly links the cyclic mobility of sand with reversible and irreversible dilatancy, enabling the unified description of monotonic and cyclic loading; (3) introduces critical state soil mechanics concepts to achieve unified modelling of sand under different states.
The critical, maximum stress ratio and reversible dilatancy surfaces follow a rounded triangle in the pi plane similar to the Matsuoka-Nakai criterion.
When this material is employed in regular solid elements (e.g., FourNodeQuad, Brick), it simulates drained soil response. When solid-fluid coupled elements (u-p elements and SSP u-p elements) are used, the model is able to simulate undrained and partially drained behavior of soil.
matTag|int|integer tag identifying material G0|float|A constant related to elastic shear modulus kappa|float|bulk modulus h|float|Model parameter for plastic modulus M|float|Critical state stress ratio dre1|float|Coefficient for reversible dilatancy generation dre2|float|Coefficient for reversible dilatancy release rdr|float|Reference shear strain length alpha|float|Parameter controlling the decrease rate of irreversible dilatancy dir|float|Coefficient for irreversible dilatancy potential lambdac|float|Critical state constant ksi|float|Critical state constant e0|float|Void ratio at pc=0 np|float|Material constant for peak mobilized stress ratio nd|float|Material constant for reversible dilatancy generation stress ratio ein|float|Initial void ratio rho|float|Saturated mass density
The material formulations for the CycLiqCP object are:
'ThreeDimensional''PlaneStrain'
See also here
REFERENCES: Wang R., Zhang J.M., Wang G., 2014. A unified plasticity model for large post-liquefaction shear deformation of sand. Computers and Geotechnics. 59, 54-66.