The shear modulus of intact rock is obtained from G=E/2(1+v).
I want to numerically(FLAC3D or 3DEC) calculate the shear modulus of intact rock as the ratio of shear stress to shear strain. Has anyone done this before who can help me?
I have written the FISH related to shear strain and I have also written the FISH related to shear stress as below, but the output is not correct.
def yzstress
yzstr=0
count =0
bh=block_head ;index to list of blocks
loop while bh # 0
bz=b_zone(bh) ;index to block zone list
loop while bz # 0
zy1=z_y(bz) ;y-coordinate of zone centroid
if zy1>0.1 then
yzstr=yzstr+z_syz(bz) ;yz-stress
count=count+1
end_if
bz=z_next(bz) ;index to next zone in block list
end_loop
bh=b_next(bh) ;index of next block in main list
end_loop
yzstress= yzstr/count
end
This code is related to 3dec.
The FISH related to shear strain is correct, but the FISH related to shear stress may be wrong because the amount of stress applied at the boundary to the model is not applied to the output of the FISH. For example, a stress of 2 MPa is applied to the model at the boundary, but the FISH shows no more than 1.3 MPa shear stress.
It seems like you have written FISH code to calculate the yz-stress in a FLAC3D or 3DEC model. However, you are concerned that the output is not correct, and the calculated shear stress is lower than the applied boundary stress.
One possible reason for this discrepancy could be due to the boundary conditions applied in your model. If the stress is not applied uniformly throughout the model or if the boundary conditions are not correctly specified, it could result in differences between the applied stress and the calculated stress in your FISH code.
To ensure that the boundary conditions are correctly specified and that the stress is applied uniformly throughout the model, you can try the following steps:
If you have tried these steps and are still not able to resolve the issue, you may want to seek help from the technical support team of the software you are using or consult with a subject matter expert in the field of rock mechanics.
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