Experimental Study on Hydro-mechanical Behaviour of Anisotropic Columnar Jointed Rock-Like Specimens

Columnar jointed rock masses (CJRM), characterized by regular arrays of polygonal prisms or columns, are exposed in the dam foundation of the Baihetan hydropower station and pose a challenge to the stability of the project. To understand the hydro-mechanical behaviour of Baihetan CJRM, triaxial compression experiments are carried out on artificial CJRM specimens with regular arrays of hexagonal columns, which are similar to the actual CJRM. Based on the experimental results, mechanical and hydraulic behaviour of CJRM is studied. It is found that the compressive strength of CJRM varies in a typical U-shape with the joint inclination angle. Three failure modes associated with the angle of joint inclination are observed. The evolution of permeability with stress exhibits distinct phased characteristics: initial compression stage, linear elastic stage, yield stage, and strain-softening stage. The results of this study provide helpful information for the design and construction of the Baihetan project involving CJRM.