Hello,

Your question is very general. First you need to specify if you have data available from advanced laboratory testing (cyclic) or good quality in-situ measurements in order to appropriately calibrate the value. But, it is also very important to specify which constitutive model (ex. PM4SAND, UBCSAND-PLM, HSs) you want to use, since for different constitutive models this value may be considered in a different manner.

If you don't have good quality data available from lab tests, there are some "first order" calibration strategies for each model that you can use based on easy to find parameters, such as the relative density or the number of SPT blow counts N, for instance.