In Korea, base-rock exists at shallow depth (30~50m). 

The measurement of rock mass properties is very important in order to design and construct underground structures, tunnels economically and reliably.

Since nonlinear deformational characteristics are determined by strain level and the condition of rock mass, it is strongly necessary to develop an experimental device to analyze the nonlinear characteristics of rock masses with various strain level and joint characteristics.

The RMDT (Rock mass dynamic test) is developed to measure strain-dependent elastic wave velocity, modulus and damping ratio, and using these properties the dynamic behavior of jointed rock masses are characterized through Resonant Column/Torsional Shear test.