Usage of UCSDSAND3 and UCSDCLAY

The syntax to use the soil models in FLAC3D is shown below. Definition of the soil parameters for UCSDCLAY and UCSDSAND3 can be found here.

1) UCSDSAND3 model

zone cmodel assign ucsdsand3
zone prop refShearModul ... refBulkModul ... frictionAng ...
peakShearStra ... refPress ... pressDependCoe ... PTAng ...
mType ... ca ... cb ... cc ... cd ... ce ... da ... db ... dc ...
noYieldSurf ... grTab ...
prop liquefac1 ... liquefac2 ... pAtm ... cohesi ...

Input example:
zone cmodel assign ucsdsand3 zone prop refShearModul 7.3700E4 refBulkModul 1.96800E5 frictionAng 3.03E1 peakShearStra 0.1 refPress 1.01E2 pressDependCoe 5.E-1 PTAng 2.53E1 mType 0 ca 0.012 cb 3.0 cc 0.4 cd 9.0 ce 0.0 da 0.3 db 3.0 dc -0.3 noYieldSurf 20 grTab "" liquefac1 1 liquefac2 0 pAtm 1.01E2 cohesi 1.73E0 range cmodel 'ucsdsand3'

2) UCSDCLAY model

zone model ucsdclay
zone prop shearModul ... poissonRatio ... shearStrength ... peakShearStra ...
noYieldSurf ... grTab ...

Input example:
zone cmodel assign ucsdclay zone property shearModul 6.0e4 poissonRatio 4.0625e-1 shearStrength 3.7e1 peakShearStra 0.1 noYieldSurf 20 range cmodel 'ucsdclay'

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Backbone Curve

In the UCSD soil models, the shear stress-strain backbone curve is represented by the hyperbolic relationship when a modulus reduction curve is not provided. To define a modulus reduction curve please specify a table for grTAB with the corresponding shear strain and G/Gmax curve.

grTab -- Table # for user-defined modulus reduction curve (G/Gmax). A separate FLAC3D command table is needed to define the modulus reduction curve. In this case, the number of the points specified will be used as the Number of yield surfaces.

Note: Please plot the shear stress-strain curve based on the specified modulus reduction curve and make sure the modulus reduction curve you're using is reasonable. The provided modulus reduction should be specified at the reference pressure and will be used to define the shear strength. For help generating a modulus reduction curves see below.

Click here for some sample modulus reduction curves, or visit http://soilquake.net/openseespl/ to download OpenSeesPL which can be used to define a modulus reduction curves based on the specified confinement and material properties. (See U-Sand2A under soil properties in OpenSeesPL and activate the User-defined Backbone Curve option.)