Abstract: Based on the geometrical morphology of the columnar jointed rock mass at the dam foundation of Baihetan Hydropower Station, a water-soluble polyvinyl alcohol (PVA) material was introduced, and the columnar jointed rock mass network structure with different inclination angles was established. The columnar jointed rock mass samples were prepared by cement mortar as rock-like materials using 3D printing technology to study the anisotropic mechanical characteristics of the columnar jointed rock mass. The anisotropic mechanical characteristics of columnar jointed rock mass were analyzed by uniaxial compression test in a laboratory. The results show that the anisotropy of columnar jointed rock mass depends on the dip angle of the joint. Peak strength and modulus of columnar jointed rock mass show an approximate “U” shaped curve with the increase of joint dip angle. In the uniaxial compression test, the cleavage cracks perpendicular to the axial direction of the cylinder, the shear cracks along the longitudinal joint plane, and the tensile cracks parallel to the axial direction of the cylinder are mainly produced. According to the evaluation of mechanical anisotropy, it is found that the anisotropy degree of peak strength and residual strength are 0.68 and 0.52, and the anisotropy degree of elastic modulus and deformation modulus are 0.61 and 0.63. The research results provide a reference for the study of the anisotropic mechanical properties of columnar jointed rock mass.

Key words: rock mechanics, columnar jointed rock mass, anisotropy, 3D printing, laboratory test