WIPP-Type Models: Parallel-Plate Viscometer

Note

To view this project in FLAC3D, use the menu command Help ? Examples…. Choose “Creep/ ParallelPlateViscometerWIPP” and select “ParallelPlateViscometerWIPP.f3dprj” to load. The project’s main data files are shown at the end of this example.

The parallel-plate viscometer test using the classical creep models is repeated to test the WIPP-type creep models (WIPP model, WIPP-Drucker model, and WIPP-Salt model). The analytical solution for the parallel-plate test assumes the viscosity is constant. In the WIPP-type creep models, the viscosity is dependent on the deviatoric stress, so a direct comparison cannot be made. As an alternative, the FLAC3D solution is compared to that obtained from the two-dimensional program, FLAC. The FLAC3D model uses the same grid as that shown and the same boundary conditions as those described in parallel-plate viscometer test using the classical creep models. The model can be directly compared to the FLAC model.

The WIPP model component is also tested in the WIPP-Drucker model (zone cmodel wipp-drucker) and the WIPP-Salt model (zone cmodel wipp-slat) for the viscometer test. The values of shear and tensile strength are set high to prevent plastic failure in the WIPP-Drucker model, and the values of initial and final density are set equal to prevent viscous compaction in the the WIPP-Salt model. The additional commands for these models are contained in data files. Upon execution of the data file with each model activated, results identical to those produced with the WIPP model are obtained.

The contours of x-velocity from FLAC3D and FLAC are compared in Figure 1 and Figure 2. The \(\sigma_{xx}\)-contours from the two programs are compared in Figure 3 and Figure 4.

Figure 1: Contours of x-velocity from the FLAC3D WIPP model.

Figure 2: Contours of x-velocity from the FLAC WIPP model.

Figure 3: Contours of \(\sigma_{xx}\) from the FLAC3D WIPP model.

Figure 4: Contours of \(\sigma_{xx}\) from the FLAC WIPP model.

Data File

;------------------------------------------------------------
; Parallel plate viscometer -- WIPP model
;                           -- WIPP-Drucker model
;                           -- WIPP-Salt model
;-------------------------------------------------------------------
model new
model largestrain off
fish automatic-create off
model title "PARALLEL-PLATE VISCOMETER (WIPP Model)"
model configure creep
;
zone create brick size 10 5 2
zone face skin
zone cmodel wipp
; zone cmodel wipp-drucker
; zone cmodel wipp-salt
;
zone property shear 12.4e9 bulk 20.7e9
zone property constant-gas 1.987 activation-energy 12e3 exponent 4.9 constant-d 5.79e-36
zone property constant-a 4.56 constant-b 127 creep-rate-critical 5.39e-8 temperature 300
;
;zone property tension 1e10 friction-drucker 0.0 dilation-drucker 0.0 cohesion-drucker 1e10            ;  WIPP-Drucker properties
;zone property compaction-0 0.0 compaction-1 0.0 compaction-2 0.0 bulk-final 20.7e9 shear-final 12.4e9 ;  WIPP-Salt properties
;zone property density-salt 2600 density-final 2600                                                    ;  WIPP-Salt properties
;
zone face apply velocity-x   0.0 range group 'West'  or 'North'
zone face apply velocity-y   0.0 range group 'North' or 'South'
zone face apply velocity-z   0.0
zone face apply velocity-y -1e-9  range position-y 5
; forces at r.h.s boundary
zone gridpoint fix force-applied-x 2.25e5 range position-x 10 position-y 0 position-z 0
zone gridpoint fix force-applied-x 4.32e5 range position-x 10 position-y 1 position-z 0
zone gridpoint fix force-applied-x 3.78e5 range position-x 10 position-y 2 position-z 0
zone gridpoint fix force-applied-x 2.88e5 range position-x 10 position-y 3 position-z 0
zone gridpoint fix force-applied-x 1.62e5 range position-x 10 position-y 4 position-z 0
zone gridpoint fix force-applied-x 4.50e5 range position-x 10 position-y 0 position-z 1
zone gridpoint fix force-applied-x 8.64e5 range position-x 10 position-y 1 position-z 1
zone gridpoint fix force-applied-x 7.56e5 range position-x 10 position-y 2 position-z 1
zone gridpoint fix force-applied-x 5.76e5 range position-x 10 position-y 3 position-z 1
zone gridpoint fix force-applied-x 3.24e5 range position-x 10 position-y 4 position-z 1
zone gridpoint fix force-applied-x 2.25e5 range position-x 10 position-y 0 position-z 2
zone gridpoint fix force-applied-x 4.32e5 range position-x 10 position-y 1 position-z 2
zone gridpoint fix force-applied-x 3.78e5 range position-x 10 position-y 2 position-z 2
zone gridpoint fix force-applied-x 2.88e5 range position-x 10 position-y 3 position-z 2
zone gridpoint fix force-applied-x 1.62e5 range position-x 10 position-y 4 position-z 2
zone gridpoint fix force-applied-y -1.2e5 range position-x 10 position-y 1 position-z 0
zone gridpoint fix force-applied-y -2.4e5 range position-x 10 position-y 2 position-z 0
zone gridpoint fix force-applied-y -3.6e5 range position-x 10 position-y 3 position-z 0
zone gridpoint fix force-applied-y -4.8e5 range position-x 10 position-y 4 position-z 0
zone gridpoint fix force-applied-y -2.4e5 range position-x 10 position-y 1 position-z 1
zone gridpoint fix force-applied-y -4.8e5 range position-x 10 position-y 2 position-z 1
zone gridpoint fix force-applied-y -7.2e5 range position-x 10 position-y 3 position-z 1
zone gridpoint fix force-applied-y -9.6e5 range position-x 10 position-y 4 position-z 1
zone gridpoint fix force-applied-y -1.2e5 range position-x 10 position-y 1 position-z 2
zone gridpoint fix force-applied-y -2.4e5 range position-x 10 position-y 2 position-z 2
zone gridpoint fix force-applied-y -3.6e5 range position-x 10 position-y 3 position-z 2
zone gridpoint fix force-applied-y -4.8e5 range position-x 10 position-y 4 position-z 2
;
model creep active on
model creep timestep fix 1e4
;
model step 900
model save 'wipp'
;
return