Abstract:The geological origin of columnar jointed rock mass is very complicated,its geological structure arranges regularly or irregularly,which is not same as common rock mass,so different methods should be adopted in fracture statistics and random simulation of joints. According to the geological structure of the columnar joints and in-situ data,columnar joints are simulated randomly by Voronoi method,which can effectively solve the problem in the random simulation of columnar joints. With the introduction of random model into 3DEC,3D random columnar joint model can be set up;and then the numerical test is carried out. Following conclusions can be drawn. (1) The size of representative elementary volume(REV) is about 3 to 4 times of the typical joint size. (2) Elastic modulus and Poisson¢s ratio show great differences in the horizontal and vertical directions,which indicates that the columnar joints have strong anisotropy. Elastic modulus and Poisson ratio in horizontal direction show little differences,so the material property can be considered same in REV scale;and columnar joints can be computed and analyzed as transversely isotropic material.