Abstract:The randomicity of fractures¢ shape(fracture orientation,dip,trace length,width,and spacing) and distribution are considered,and Monte Carlo technique is adopted to develop a code RFNM. By RFNM,not only the virtual fractured rock mass,in which the structure information of fractures is described and the real engineering rock mass is represented,can be generated,but also the fractured rock mass model can be discretized and then combined with numerical methods to solve practical engineering problems. Therefore,the virtual fractured rock mass with random fracture networks is in fact one digital fractured rock mass model. In addition,FEM is adopted to develop the GeoCAAS(geo-engineering computer aided analysis system) code. The mechanical and hydraulic properties of fractured rock mass are studied by numerical tests. The results provide the evolutionary laws of deformation modulus and permeability with the increase of fracture trace length. Furthermore,the relationship between deformation modulus and permeability is discussed.