Hello all,
I have a task to find thickness of a water tank immersed under ground. So, to properly set boundary conditions in my finite element model I created two pars 1) the water tank 2) soil/sand around.
Is it acceptable to set just a elastic model for a soil with very small stiffness E=0.1-0.2 MPa and nu=0.49 ?
P.S. I know that is better to use more advanced models with plasticity and hardening, but I need to do lots of calculations, so simple models are preferred.
What are the common practices?
Yes, using a linear elastic soil model is acceptable for efficiency and a limited range of deformation. However, a stiffness between 0.1 and 0.2 MPA seems way too low for sand. Thee are various sources for rough estimates of the stiffness of sand. For instance here:
https://geotechdata.info/parameter/soil-young-s-modulus
HEnce, a better estimate for compacted sand is between 10 and 80 MPa.
This gives sufficiently reliable boundary conditions without needing advanced soil models, as long as your strain is below 0.1%.
(Soil is not what I typically use in my modeling, so consider my response with care)
Raffael Bogenfeld I see, I also found this link and it is useful. If stiffness (young's modulus) is about 10-80 MPa, the "sand" is too stiff under tension, (rubber has stiffness about 20 MPa) results are dramatically different. So, I need somehow cut off stiffness under compression. Probably, Drucker-Prager model is better for this purpose.
good subject!
k=0.03~0.1 N/mm3
we are doing research project and I will check the value
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