Mod-Ta-Ger¶
A fabric-extended Ta-Ger model. Mod-Ta-Ger retains the Ta-Ger formulation
in a self-contained class and adds three fabric parameters (zmax, cz and
alpha) to improve the cyclic and dilatancy response. The Ta-Ger parameters
and conventions carry over; the additional parameters default to zmax = 4,
cz = 600, alpha = 13.
At a glance
- Class:
ACT.models.mod_ta_ger - numgeo name:
Mod-Ta-Ger - Parameters with search bounds: 14
- Imported as:
from ACT.models import mod_ta_ger
Units and angles
Enter phics in degrees and Kw in kPa; Kw is used only for
undrained simulations. Keep pressure inputs in kPa when calibrating Q and
R. The interpretation and units of G0 depend on Gmodel; zmax, cz
and alpha are dimensionless. See the
numgeo Ta-Ger formulation
before transferring parameters between shear-modulus modes.
Default parameter values¶
Mod-Ta-Ger uses the Ta-Ger parameter set
and adds:
| Parameter | Default |
|---|---|
zmax |
4 |
cz |
600 |
alpha |
13 |
Default search bounds¶
These are the built-in lower/upper bounds used when a parameter is optimized. Override any of them with set_bounds.
| Parameter | Lower | Upper | Description |
|---|---|---|---|
G0 |
1. | 10000. | shear-modulus constant |
m |
0.3 | 1.0 | |
nu |
0.0 | 0.45 | Poisson's ratio |
Q |
8.0 | 11.0 | |
R |
0.25 | 1.50 | Bolton relative-dilatancy parameter |
emin |
0.2 | 1.2 | minimum void ratio |
emax |
0.3 | 1.6 | maximum void ratio |
phics |
25.0 | 42.0 | critical-state friction angle (degrees) |
delta |
0.0 | 5.0 | |
kappa |
0.6 | 1.0 | |
Gmodel |
1.0 | 2.0 | shear-modulus model switch (1 or 2) |
zmax |
0.0 | 20.0 | maximum fabric (dilatancy) |
cz |
1.0 | 5000.0 | fabric-evolution parameter |
alpha |
0.0 | 30.0 | pyknotropy / fabric exponent |
Setting parameters¶
Assign initial / fixed parameter values with set(...):
from ACT.models import mod_ta_ger
model = mod_ta_ger()
model.set(G0=..., m=..., nu=..., Q=..., R=..., emin=...)
Full set signature
set(G0=None,m=None,nu=None,Q=None,R=None,emin=None,emax=None,phics=None,delta=None,kappa=None,Gmodel=None,zmax=None,cz=None,alpha=None,Kw=None)
Available set parameters: G0, m, nu, Q, R, emin, emax, phics, delta, kappa, Gmodel, zmax, cz, alpha, Kw.
Choosing free parameters¶
Narrow the search interval of selected parameters, then list the ones to optimize in globals.setup:
model.set_bounds(G0=[1., 10000.], m=[0.3, 1.0], nu=[0.0, 0.45], Q=[8.0, 11.0])
globals.setup(Model=model, Free_parameter=["G0", "m", "nu", "Q", "R", "emin"], ...)
Parameters that accept a set_bounds override: G0, m, nu, Q, R, emin, emax, phics, delta, kappa, Gmodel, zmax, cz, alpha.
Reading & updating single parameters¶
See the models overview for the common interface shared by all models, and Optimization for how the free parameters are searched.