Experimental and analytical research on shear-flow coupling mechanism in rock joints

It requires remarkably good attention while designing radioactive waste repository in comparison to other conventional underground structures constructed in rock mass. Economical efficiency, environmental issue and structure's safety are some the prominent features in this regard. Therefore it is necessary to appropriately grasp the mechanical, permeability and these coupling characteristics of rock joints. The purposes of this study are; 1) to develop a new shear-flow coupling test apparatus, 2) to evaluate mechanical and hydraulic properties of rock joints under the shear-flow coupling condition, 3) to evaluate the asperity and the aperture of rock joint, 4) to simulate the shear-flow coupling behavior of rock joint by using experimental data. As a result of conducting the shear-flow coupling test to verify the new apparatus, it is understood that the new equipment can quantitatively evaluate the effect of the rotation of the upper box and it can also carry out permeability testing under the linear flow condition. In addition, it clarified that the effect caused by the rotation of the upper box was remarkable for shear-flow coupling properties of rock joint, when the normal stress increases. At first, it succeeded to define the width of initial aperture of rock joint by using GIS (Geographic Information System) method. Furthermore, it carried out the simulation of the shear-flow coupling test by using the geometrical data of rock joint. By the comparison of the simulation and experimental results of shear stress and hydraulic conductivity during shearing, it indicated that the predicted results approximately agree with the experimental result, especially after 10 mm of shear displacement. The result also indicated that the proposed method is very effective to simulate shear-flow coupling behavior. (author)