Referring to the question and answer about Rinter (https://communities.bentley.com/products/geotech-analysis/f/plaxis-soilvision-forum/212033/rinter-value)
We typically do not recommend parameter values as this should be based on data collected from your investigation, laboratory data, engineering experience and judgment.
What kind of investigation or laboratory tests are most commonly carried out to obtain Rinter values?
On a very (very) rough estimation, considering interaction with sand and concrete values of Rinter between 0.8-1.0 can be used, and with clay with concrete values between 0.7-1.0. However, it is very difficult to say exactly what value would best fit your analysis.
Are there any literatures or publications that help us to roughly determine Rinter values?
Dear Yohel,
Indeed, this value can vary from sand to sand and from clay to clay.
In general, the value of Rinter should never be a critical parameter in your model as it is a very arbitrary factor. That means that if by changing the value from 0.8 to 0.7, you get to see a very different picture it means that using the Rinter is not the right way to simulate the interface between your soil and structure.
Instead, you can use a Custom material that can be assigned to the interface (default is From adjacent soil), which can be a dedicated material with the sole purpose of modelling the behaviour of the interface. Then, you are allowed to directly determine the stiffness and strength of the interface.
As usual in modelling a sensitivity analysis may be necessary to determine which value best fits the expected behaviour.