Itasca Flac2D 8.0

Description

Itasca Flac2D 8.0

64-Bit Version
With the 64-bit version of FLAC, models can now be substantially larger with more zones, nodes, and structural elements.
 
New and Updated Constitutive Models
Five new and updated constitutive models are available in FLAC 8.0.
 
The Plastic Hardening (PH) model is a shear and volumetric hardening constitutive model for the simulation of soil behavior. The new PH model is formulated within the framework of hardening plasticity (Schanz et al. 1999), allowing the removal of the main drawbacks of the original nonlinear model formulation (e.g., detection of loading/unloading pattern, nonphysical bulk modulus). This constitutive model is also easy to calibrate using either lab tests or in-situ tests and uses familiar properties, names, and conventions in civil engineering.
 
The Cysoil model is updated. This model is a strain-hardening constitutive model for soil characterized by a frictional and cohesive Mohr-Coulomb shear envelope and an elliptic volumetric cap, associated with a shape parameter. The model features include: a cap hardening law, to capture the volumetric power law behavior observed in isotropic compaction tests; a friction-hardening law, to reproduce the hyperbolic stress-strain law behavior observed in drained triaxial tests; and a compaction/dilation law to model irrecoverable volumetric strain taking place as a result of soil shearing.
 
Compared to the Cysoil model implemented in FLAC 7.0, these features are all built into the updated version. The updated Cysoil model retains the capability to substitute, by means of tables, alternative user-defined hardening/softening laws for the built-in laws. When a table is declared for a specific model property of friction, dilation, cohesion, tensile strength, or cap-pressure, the associated user-defined law takes precedence over the corresponding built-in law.
 
The swell model is based on the Mohr-Coulomb constitutive model with non-associated shear and associated tension flow rules. The difference is that the wetting-induced deformations are taken into account by means of coupling wetting strains with the model state prior to wetting.
 
The anisotropic ubiquitous elastic model accounts for the presence of an orientation of weakness (weak plane) in a FLAC elastic-anisotropic model. The plane of weakness has the same orientation as the plane of elastic isotropy. The criterion for failure on the plane, whose orientation is given, consists of a Mohr-Coulomb envelope with tension cutoff.
 
The ubiquitous viscoplastic creep model combines two existing models in FLAC, the power-law viscoplastic model and ubiquitous-joint model. The model simulates the viscous-elastic-plastic mechanical behavior of ubiquitous joint rock with cpower-type creep occurring in a rock matrix.
 
Speed Increase
FLAC 7.0 introduced multithreaded calculations of the equations of motion and constitutive relations. FLAC 8.0 adds multithreaded calculations for fluid flow for faster and more efficient solutions. Speed increases will vary from computer to computer based on factors including number of processors, processor architecture, and available RAM. The multithreading does not operate if a FISH constitutive model is assigned in the model.
 
Boundary Relaxation
The boundary relaxation feature is used to slowly and systematically reduce forces along a boundary. This can be used to simulate the 3D effect of a tunnel advance.  It is also useful when modeling weak materials and/or in high stress fields by preventing artificial dynamic failure of zones around the excavation due to large tensile stress waves that are purely numerical.

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