Based on Mohr-Coulomb(M-C) criterion,the parameters of Druker-Prager(D-P) criterion for geomaterial were determined under non-associated flow rule,and thus a new D-P type criterion was presented.Two assumptions were employed during the derivation:1) principal strains by M-C model and D-P model are equal,and 2) the material is under plane strain condition.Based on the analysis of the surface on π plane,it is found that the proposed D-P type criterion is better than the D-P criterion with M-C circumscribed circle or M-C inscribed circle,and is applicable for stress Lode angle less than zero.By comparing the predicted results with the test data of sand under plane strain condition and other D-P criteria,the proposed criterion is verified and agrees well with the test data,which is further proved to be better than other D-P type criteria in certain range of Lode angle.The criterion was compiled into a finite difference package FLAC3D by user-subroutine,and was used to analyze the stability of a slope by strength reduction method.The predicted slope safety factor from the proposed criterion agrees well with that by Spencer method,and it is more accurate than that from classic D-P criteria.
