Abstract: Based on experiments on marble, red sandstone and granite, their ultimate envelope can be averaged as straight lines. With these lines, their slope and bonding stress can be calculated. Two hardening parameters should be decided by data of some points on stress-strain curve before peak strength. According to experiments, the occurrence of failure isn’t far away from phase change, so the phase change parameter can’t be computed by Desai’s method. The authors think that taking a value of a little greater than 2 is appropriate. When back predicting stress-strain curve, the authors proposed a simple and applicable method, regarded the end of initial compression phase as initial condition to calculate initial hardening parameter and trajectory of plastic strains.

Key words: hierarchical single surface(HISS) model, ultimate envelope, bonding stress, hardening parameter, phase change parameter, initial condition