4.15.2.2. CycLiqCPSP

nDMaterial('CycLiqCPSP', matTag, G0, kappa, h, M, dre1, dre2, rdr, alpha, dir, lambdac, ksi, e0, np, nd, ein, rho)

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.