Ubiquitous-Anisotropic Model and Columnar-Basalt (COMBA) Model

FLAC3D
1

Hi guys, I recently modelled the excavation of a powerhouse considering an anisotropic weak layer. Youngs modulus and shear strength parameters in plane- and normal direction were totally different. I have used Ubiquitous-Anisotropic Model and Columnar-Basalt (COMBA) Model to simulate the anisotropic weak layer.

Before the simulation of excavating the power house, I did some element tests for both constitutive model. The results are attached below. They are almost identical.

UBA&COMBA
UBA&COMBA1500×1125 121 KB

Then I turned into excavation of the power house. You see the fish-parameters below:

[global E_plane = 15.9e9*1e-6
[global v_plane = 0.27
[global c_plane = 3.6e6*1e-6
[global f_plane = 40.7
[global E_normal =7.97e9*1e-6
[global v_normal =0.25
[global c_normal = 2.4e6*1e-6
[global f_normal = 36.6

However, the displacements of both cases were different, as attached. The maximum displacement should supposed to be as similar to the case of COMBA. In case of UBA, the displacement in weak layer was smaller than others (not expected). If anyone can give some suggestions for this problem?

UBA&COMBA2
UBA&COMBA21720×738 105 KB

The assigned properties for both are listed below. The dip angle and dip direction of weak layer are same as given in the fish codes.

[global dip = 65
[global dd = 30
zone property young [E_plane] poisson [v_plane] cohesion [c_plane] friction [f_plane] tension [0.15] &
                space-1 0.27 stiffness-norm-1 [60e3] stiffness-shear-1 [60e3 ]  &
                dip-1 [dip] dip-direction-1 [dd]  &
                j-cohesion-1 [c_normal] j-friction-1 [f_normal] j-tension-1 [0.1]  &
                flag-matrix-plastic on range cmodel "columnar-basalt"

zone property young [E_plane] poisson [v_plane] cohesion [c_plane] friction [f_plane] range cmodel "columnar-basalt" not

[global dip = 65
[global dd = 30
zone property young-plane [E_plane] poisson-plane [v_plane] cohesion [c_plane] friction [f_plane] tension [0.17e6*1e-6] range cmodel "Ubiquitous-Anisotropic"
zone property young-normal [E_normal] poisson-normal [v_normal] shear-normal [G_normal] range cmodel "Ubiquitous-Anisotropic"
zone property dip [dip] dip-direction [dd] joint-cohesion [c_normal] range cmodel "Ubiquitous-Anisotropic"
zone property joint-friction [f_normal] joint-dilation 0 joint-tension [0.10e6*1e-6] range cmodel "Ubiquitous-Anisotropic"

zone property young [E_plane] poisson [v_plane] cohesion [c_plane] friction [f_plane] range cmodel "Ubiquitous-Anisotropic" not