Abstract
The factors of discontinuity plane which affect the shear behavior of rock joint are the strength of intact rock, roughness, aperture etc. In these factors, there is many researches in related with the roughness. However, although the aperture condition of rock joint is important factor, the many researches with this factor have not been performed. In this paper, the effects of which the shear behavior of rock joint is depended on the magnitude of aperture condition are discussed. Especially, the numerical index representing the degree of the aperture condition with rock joints is proposed, and furthermore, we applied this index on the shear strength equation proposed by authors.