Abstract: As a special rock mass, rock mass with columnar joints has a different geological structure with the conventional rock masses. The columnar joints are generally having irregular and variable joint plane and the cross section of the columnar joints are also irregular and have incomplete incision. Joints and fissures are well developed inside the columnar structures and these defects contribute to the relatively lower modulus and low shear strength. The concentrated split zones can also be observed in same rock mass. As the foundation of a concrete arch dam, the rock mass is required to have sufficient bearing capacity and stability. However, due to the unique tectonic structure of the columnar jointed rock mass with welldeveloped structural planes, it is necessary to evaluate the performance of the basalt bedrock with the columnar joints under the loading conditions as well as the impact of the consolidating grout at the faulted and broken zones on the integrity, strength and stiffness parameters. The consolidating grout reduced the deformation resistance, increased the shear strength and remediated the seepage at the structured plane of the rock mass.

Key words: Columnar Joints, Basalt Bedrock, Consolidating Grout, Coefficient of Permeability, Acoustic Wave Velocity, Cement Injected