Hello; new to this very interesting software and somewhat to FEM modelling as well, so apologies if some of these questions seem obvious. I am also not familiar with script writing, so if it is difficult to determine where something is, please let me know and I can clarify.

I am building an earthfill dam model and have a few questions:

1) I can get a small model to work with the H-S soil material in the attached script, but when I scale it up to the dam model, I get the error "Plastic-Hardening model: material combination is not favorable for internal parameter calculation". I'm assuming this is a convergence issue, but is there a way to better troubleshoot where the error is/how to refine it? I am lacking H-S soil parameters (see point 4 below), but believe that my initial inputs should be within an acceptable range to be able to complete the analysis. Any thoughts on the where my H-S parameters might be way off? (most are defined as variables above the material definitions, while some are left as default).

2) In the second attached script (50m hydro pressure), I have added a for/loop function that applies hydrostatic pressure up the dam slope as a function of water height. However, I can't seem to get it to this stress function to cover the entire range it is supposed to. Any suggestions on where I might be going wrong here? (starts at line 279)

3) While both models will not run with the current H-S material parameters, swapping these out for M-C parameters (attached) will allow them to run. (replace lines 153 to 276 with attached M-C parameter script).

4) I am trying to validate the model with measured deformations and previous initial filling stage modelling. However, original modelling was completed using Duncan-Chang Hyperbolic Soil (HB) model. I understand the H-S model is derived from the HB model; however, I lack a lot of the soil information required to properly establish the H-S model (while I have HB modelling parameters). Is there any way to complete an HB analysis based on script input? If so, any suggestions on this?

Thanks in advance for any help anyone can provide.

• I just skimmed through your model and realized that you do not specify the principal stress parameters when you use H-S material. please take a look at the page 9 of the tutorial 08. Principal stresses are the main parameters that need to be initialized when H-S constitutive model is assigned. Since principal stress varies by location, a simple javascript function is written to go through each element and manually calculate the principal stresses from the model and assign it to the constitutive model as shown in "initial_principal_stresses.ajs" (page 23 of the tutorial). Please note that initial stresses are zero at the beginning of the run so you need to solve your model with elastic constitutive model and then run the script when initial stress stablished. sometimes geometry is simple and you will be able to calculate the stresses directly and assign it to both constitutive model and model itself. I usually pick the first approach.
• regarding the HB and HS parameters, please go to the link below and read the FLAC3D manual carefully. Some assumptions can be made to come up with some default parameters. https://docs.itascacg.com/flac3d700/common/models/hardening/doc/modelhardening.html

Thanks for the response; I had missed tutorial 8, it is very helpful.

When creating the P-Hardening material in the tutorial, it seems that the principal stresses are not added to the material definition (the material input line terminates after "dilation"). If I understand correctly, the variables sig1/2/3_val are applied directly to the gauss points with "setelem("prop","sig1",eid,j+1,sig1_val);" once the model is run again and the nodes are zeroed, going to edit material shows sig1/sig2/sig3 are all 0. However, if I add the variables sig1/2/3_val to the original P-H material definition, I can review sig1/sig2/sig3 values in the material editor afterwards. Would this be another way to do it, or is this incorrect as it is only showing the last sig1/sig2/sig3 value and adding it to all material types?

In the case of wanting to run through multiple iterations of the model with changing reservoir levels, some of my material types change (saturated material corresponding to the reservoir level). When I re-assign these regions, do I need to re-run the initial principal stress parameter, or will the original values remain assigned to the gauss points regardless of the materials assigned to these regions? I want to model the deformation response under fluctuating reservoir levels (up and down), so I believe that will not want to re-zero the nodes after the first stage.

Thanks again. Attached is a combined script showing what I currently am working with (solve elastic constitutive model, assign P-H soil models, run principal stresses, re-solve and zero nodes, add hydrostatic water function and re-assign regions, re-solve).

if the change in stress is noticeable, I believe you need to modify the principal stress via script. Please note that, I have not done it myself so double check it with other sources to make sure.