Hi there
I am trying to model a deep excavation in unsaturated conditions. As I only have suction measurements during dry and wet periods, I have been trying to input then as pore-presure in the user-defined water condition of certain clusters (clay materials next to wall). However, it is not possible to input positive values (suction).
I am not sure if it is the best way of model this, I will appreciate any advise on this.
Regards,
Dear Eduardo,
There are 2 possible ways to model this:
1) Instead of directly specifying the suction, you should specify a degree of saturation. To do so, set the Water Condition to "Unsaturated" and specify the degree of saturation.
2) Choose the correct SWCC for the soil in which you have the suction measurements.
With kind regards,
Dennis Waterman
Thanks Dennis.
Yes, I ended up playing with the degree of saturation in some clusters to get the desired suction. I know the proper way would be a numerical coupled analysis of moisture transfer in an unsaturated soil having an SWCC curve model. Unfortunately, the only data I have are historical measured suction values in dry and wet seasons. So for a short-term analysis, I input the historical data for dry season, and for long-term analysis, I reduce my suction following the historical data in the wet season.
My question now is, how can I model any volumetric change due to this difference in suction? Does plaxis take any volumetric change into account when saturation is manually changed? Or, do I apply volumetric strains manually in some clusters?
I would really appreciate any help on this.
Best regards,
If you manually change the suction it will change the effective stresses, which will cause volumetric change. Hence, that is automatically taken into account. With kind regards,
Thanks Dennis, your answers are really appreciated
Last question, is this regardless of using Undrained A or B model?
You're welcome :) Indeed, it works for both Undrained A and B ....