Error: ***both elastic modulii zero in at lease one zone

FLAC
1

Hi everyone,
I am running the stability analysis for a staged construction of tailings dam, I used NorSand model for tailings and clay. At the end of construction, I switched the NorSand of Tailings and Clay to Mohr-Coulomb for the strength reduction method. However, it shows the error of “***both elastic modulii zero in at lease one zone”, could anyone provide some insights to this error？
thanks
Derek
;---------------------------FoS calculation---------------
ini xdisp 0 ydisp 0 yvel 0 xvel 0
set small

ini ex_1 0

def de_par
loop ii (1,izones)
loop jj (1,jzones)
if z_group(ii,jj)=‘Lower_silt_sand’
ex_1(ii,jj)=bulk_current(ii,jj)
end_if
if z_group(ii,jj)=‘Upper_silty_sand’
ex_1(ii,jj)=bulk_current(ii,jj)
end_if
end_loop
end_loop
end
de_par
;
model mo group Clay
model mo group Lower_silt_sand
model mo group Upper_silty_sand
model mo group EM_Tailings
model mo group CM_Tailings
;
def su_peak_assign
loop ii (1,izones)
loop jj (1,jzones)
if model (ii,jj)#1
$esy=-(syy(ii,jj)+pp(ii,jj))
if z_group(ii,jj)=‘Lower_silt_sand’
$poi_=0.333
bulk_mod(ii,jj)=ex_1(ii,jj)
shear_mod(ii,jj)=3.bulk_mod(ii,jj)(1.-2.$poi_)/(2.(1.+$poi_))
tension(ii,jj)=0.
friction(ii,jj)=30.
cohesion(ii,jj)=0.
end_if
if z_group(ii,jj)=‘Upper_silty_sand’
$poi_=0.333
bulk_mod(ii,jj)=ex_1(ii,jj)
shear_mod(ii,jj)=3.bulk_mod(ii,jj)(1.-2.$poi_)/(2.(1.+$poi_))
tension(ii,jj)=0.
friction(ii,jj)=30.
cohesion(ii,jj)=0.
end_if
if z_group(ii,jj)=‘Clay’
$poi_=0.49
shear_mod(ii,jj)=51.100000.
bulk_mod(ii,jj)=2.shear_mod(ii,jj)(1.+$poi_)/(3.(1.-2.$poi_))
tension(ii,jj)=0.
friction(ii,jj)=0.
cohesion(ii,jj)=max(10.,0.22$esy)
end_if
if z_group(ii,jj)=‘EM_Tailings’
$poi_=0.49
shear_mod(ii,jj)=51.100000.
bulk_mod(ii,jj)=2.shear_mod(ii,jj)(1.+$poi_)/(3.(1.-2.$poi_))
cohesion(ii,jj)=0.18$esy
tension(ii,jj)=0.
friction(ii,jj)=0.
end_if
if z_group(ii,jj)=‘CM_Tailings1’
$poi_=0.49
shear_mod(ii,jj)=51.100000.
bulk_mod(ii,jj)=2.shear_mod(ii,jj)(1.+$poi_)/(3.(1.-2.$poi_))
cohesion(ii,jj)=0.24$esy
tension(ii,jj)=0.
friction(ii,jj)=0.
end_if
end_if
end_loop
end_loop
end
su_peak_assign
solve fos

2

Norsand model is a CPP model, when the properties are extracted from or assigned to a zone, an intrinsic fish function named ‘z_prop()’ should be used, e.g.:

ex_1(ii,jj)=z_prop (ii,jj, ‘bulk_current’)
z_prop (ii,jj, ‘bulk_mod’)=ex_1(ii,jj)

Check: Use z_model(),z_prop() and z_group(). to access model and properties
or page 2 - 47 in the Fish Reference manual for more details.

3

Hi Wang,
Thanks for your reply. I still have the same problem of elastic modulii zero,
For the clay and Tailings using NorSand mdoel, is the below code correct, if not, could you please help me revise it?

if z_group(ii,jj)=‘Clay’
$poi_=0.333
z_prop(ii,jj,‘shear_mod’)=5100000.
z_prop(ii,jj,‘bulk_mod’)=2.z_prop(ii,jj,‘shear_mod’)(1.+$poi_)/(3.(1.-2.$poi_))
;cohesion(ii,jj)=0.18*$esy
tension(ii,jj)=0.
friction(ii,jj)=0.
cohesion(ii,jj)=max(10000.,0.22*$esy)
end_if

For the Lower_silt_sand using Mohr Coulomb, is the below code correct?

def de_par
loop ii (1,izones)
loop jj (1,jzones)
if z_group(ii,jj)=‘Upper_silty_sand’
ex_1(ii,jj)=bulk_current(ii,jj)
end_if
end_loop
end_loop
end
de_par
;
if z_group(ii,jj)=‘Upper_silty_sand’
$poi_=0.333
bulk_mod(ii,jj)=ex_1(ii,jj)
shear_mod(ii,jj)=3.bulk_mod(ii,jj) (1.-2.$poi_)/(2. (1.+$poi_))
tension(ii,jj)=0.
friction(ii,jj)=30.
cohesion(ii,jj)=0.
end_if

thanks
Derek

4

For NorSand model use: z_prop(ii,jj,‘shear_current’)=5100000.
For Mohr Coulomb model use: bulk_mod(ii,jj)=xxx and shear_mod(ii,jj)=xxx

5

Hi Wang,
do you mean like this?
for Norsand:
if z_group(ii,jj)=‘CM_Tailings19’
$poi_=0.49
z_prop(ii,jj,‘shear_current’)=5100000.
z_prop(ii,jj,‘bulk_current’)=2.5100000(1.+$poi_)/(3.(1.-2.$poi_))
cohesion(ii,jj)=0.24*$esy
tension(ii,jj)=0.
friction(ii,jj)=0.
I tried several times, but still get the same error.
thanks
Derek

6

Shear_current, and bulk_current in the NorSand model are read-only properties. You can extract those values from the zones, but are not allowed to modify them.

7

So what is the right code? could you please write it for me?
thanks!

8

Please send your datafiles to FLAC support.