Triaxial Compression Test with Hoek-Brown-PAC Model
Note
To view this project in FLAC3D, use the menu command . Choose “ConstitutiveModels/ TriaxialCompressionHoekBrownPAC” and select “TriaxialCompressionHoekBrownPAC.f3dprj” to load. The project’s main data file is shown at the end of this example.
Triaxial compression tests are performed on models composed of Hoek-Brown-PAC material in FLAC3D to verify the stress and strain paths that develop.
A single-zone model to simulate the triaxial loading tests is constructed in FLAC3D. The triaxial load conditions are illustrated in Figure 1. Compression loading tests are performed under two loading conditions: \(\sigma_{3}/\sigma_{ci}\) = 0 and 1.0 (\(\sigma_{3}\) = 0 and 1.0 MPa).
The triaxial tests are performed on a sample of Hoek-Brown material with the following properties:
\(m_b\) | 5 |
\(s\) | 0.5 |
\(\sigma_{ci}\) | 1.0 MPa |
\(\sigma^{cv}_3\) | 1.5 MPa |
\(E\) | 100 MPa |
\(\nu\) | 0.35 |
The analytical solutions for stress and strain during compression loading are presented by the plots shown in Figure 2 and Figure 3.
The FLAC3D results are compared to the analytical solutions in Figure 4 through Figure 7. The solutions compare within 1%.
Data File
; Triaxial tests on a Hoek-Brown material
model new
model largestrain off
fish automatic-create off
model title "Triaxial Test on a Hoek-Brown material"
call 'input_record'
@input
zone create brick size 1 1 1
zone cmodel assign hoek-brown-pac
zone property density=1.0 young=@young poisson=@poiss
zone property constant-sci=@sig_ci constant-mb=@mb constant-s=@s constant-a=@a
zone property stress-confining-prescribed=@sig3_cv
@locptrs
zone face apply velocity-y @y_vel range position-y 1
zone face apply velocity-y [-y_vel] range position-y 0
fish history @record_variables ;; 1
history interval 1000
fish history @eps_xx
fish history @eps_yy
fish history @eps_yy
fish history @sig_xx
fish history @sig_yy
fish history @sig_zz
model save 'ini'
; unconfined
fish set @sig_conf = 0.0
zone face apply stress-xx = @sig_conf
zone face apply stress-zz = @sig_conf
zone initialize stress xx = @sig_conf yy = @sig_conf zz = @sig_conf
model step @cyc
model save 'conf0'
; confined
model restore 'ini'
fish set @sig_conf = -1.0 ; negative is compression
zone face apply stress-xx = @sig_conf
zone face apply stress-zz = @sig_conf
zone initialize stress xx = @sig_conf yy = @sig_conf zz = @sig_conf
model step @cyc
model save 'conf1'
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