Evaluation of mechanical properties of natural rock joints for discontinuous numerical analysis

It is necessary to decide the appropriate modeling of mechanical behavior of a discontinuity and its material proper-ties (i.e. normal stiffness, shear stiffness, cohesion, friction and dilation angles) so as to evaluate the stability and deformational behavior of structures in the discontinuous rock masses and to design rock structures by using discontinuous numerical analysis such as DEM(Distinct Element Method). This paper presents the newly developed direct shear test techniques and a rational procedure for the determination of material properties of natural rock joints. This test equipment can be applied for not only the constant normal stress condition but also the constant normal stiffness condition, which is suitable for evaluating the deformation behavior of deep underground constructions. Moreover, test specimen was made use of boring cores sampled from the field. It can be expected to rationally evaluate the mechanical properties of rock joints when the proposed techniques of both the shear test and the quantitative evaluation procedure are applied.