Abstract:A graphical method for determining the principal stress distribution of a triaxial stress state from a fault slip state was proposed by Aleksandrowski in 1985,based on Arthaud′s concept of plane movement,Alek- sandrowski′s method,however,is only valid for the cases in which the values of the stress ratios(C)are consid- ered 1o be ,10,2,1.1 and 1.Whether the method is applicable for general cases of all values of C has not yet been confirmed.In this paper.Aleksandrowskis′ method is tested using a numerical derivation from spatial geometric analysis,and it is revealed that this method is correct for all values of stress ratios other than C=, 10,2,1.1,and 1,i.c-<C<.

Key words: fault slip; principal stress direction graphical determination; numerical derivation