Calculating strength parameters for Mohr-Coulomb models from back analysis is easy. This is not the case for IUCM (or Hoek-Brown strength envelope) because of the non-linear nature of the equation that define HB envelope.
The attached PowerPoint explains the process, and the program helps with the calculations. To “install” the program, just copy the file from the zip file to a folder and click the exe file. Done, you are ready to go.
