Dynamic analysis with PLAXIS 3D


I have a question about the soil's internal friction angle in the DYNAMIC ANALYSIS.

Whenever we perform dynamic analysis in Plaxis, we have two options for input phi:

  1. To use the given internal friction angle of the soil (obtained from static teststhat is, small strain rate of loading), or
  2. the recommended dynamic internal friction angle proposed by ''Das, B. M., & Luo, Z. (2016). Principles of soil dynamics'', which is two degrees lower than the given internal friction angle of the soil.

Which one is correct for this purpose?

Soil Mechanics / Geotechnical Analysis Design Education Software Computational Geomechanics Geotechnical Earthquake Engineering & Soil Dynamics Shallow Foundations

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Accepted Votes: -1

Sally Simpson


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.