A method for determining fractured rock mass properties is presented here o
n the basis of homogenization approach. The rock mass is considered to be a
heterogeneous medium composed of intact rock and of fractures. Its constit
utive model is studied numerically using finite element method and assimila
ting the fractures to joint elements (Coste, Comportement Thermo-Hydro-Meca
nique des massifs rocheux fractures These de Doctorat, Ecole Nationale des
Ponts et Chaussees, Paris, 1997). The method has been applied to a granite
formation in France. Geological data on different families of fractures hav
e been used for the statistical representation of the fractures. A mesh-gen
erating tool for the medium with high density of fractures has been develop
ed. The mechanical behaviour of the rock mass (elasticity, ultimate strengt
h and hardening law) has been determined assuming linear elasticity and Moh
r-Coulomb strength criterion both for the intact rock and the fractures. Ev
olution of the mechanical strength in different directions has been determi
ned as a function of the mean stress, thanks to various numerical simulatio
ns. The mechanical strength appears to be anisotropic due to the preferenti
al orientation of the fractures. The numerical results allowed us to determ
ine an oriented strength criterion for the homogenized rock mass. A 2D cons
titutive law for the homogenized medium has been deduced from numerical dat
a. A 3D extension of this model is also presented. Copyright (C) 2001 John
Wiley & Sons, Ltd.