coupled pore fluid diffusion stress analysis

anand001 · Apr 9, 2014

Hello all,

I am modeling single element in SOILS.

I am new to ABAQUS and spent time browsing through forum , but could not find the answers. I would appreciate if you could help me solve this.

model is single element, c3d8p, bottom surface fixed. triangular load applied on top surface. and pore preesure -0 defined on top surface.

1. my 1 element model runs but it gives warning "There is zero VOL. FLUX everywhere in the model based on the default criterion. please check the value of the average VOL. FLUX during the current iteration to verify that the VOL. FLUX is small enough to be treated as zero. if not, please use the solution controls to reset the criterion for zero VOL. FLUX."

I this a problem? Am I getting my answers correct in simulations even though if I am getting this warning. permeability value is of the order E-11 .

2. How to calculate total fluid loss from the element? I understand RVF and RVT gives it. But then what happens when load is removed? does the fluid comes back inside the element? Void ratio is fixed. and saturation is 1.

3. Why is saturation remaining constant when fluid flows out?

4. Does the volume of element change when load is applied? My model shows constant volume of whole element. If water flows out, it should change.. right? Or, how can i explain this phenomenon?

I would greatly appreciate, if someone can help sort me this doubts. thanks.

anand001 · Apr 9, 2014

5. Also, how to calculate what fraction of load is carried by liquid and solid phase?

6. should I use pore fluid flow in my analysis? what is significance of pore fluid flow? Or, in other words , when should I apply it?

thanks.

IceBreakerSours · Apr 10, 2014

a) Let me repeat, please do not tag in the forums. It is an unfair practice and can get you kicked out.
b) Although I've used Soils analysis before, I am no expert. So, please take these with a pinch of salt:

1. Make sure your units are consistent. And then, check them again.
2. What makes a fluid move?
4. If you are using a hybrid element, then the volume of the element will not change. Otherwise, it will.
5. I do not remember off the top of my head but I do recall that it is discussed in the Analysis User's Guide (or, perhaps, the Theory Guide). If you can not find it, ask again.

I do not know the answer to the rest of your questions. Perhaps, you should try Yahoo! Groups and LinkedIn. However, just so you are aware, do your homework (reading manuals, for instance, is expected) before you post anything - anywhere.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083