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Geomechanics and Engineering
  Volume 21, Number 3, May10 2020, pages 227-236

Preliminary numerical study on long-wavelength wave propagation in a jointed rock mass
Song-Hun Chong, Ji-Won Kim, Gye-Chun Cho and Ki-Il Song

    Non-destructive exploration using elastic waves has been widely used to characterize rock mass properties. Wave propagation in jointed rock masses is significantly governed by the characteristics and orientation of discontinuities. The relationship between spatial heterogeneity (i.e., joint spacing) and wavelength for elastic waves propagating through jointed rock masses have been investigated previously. Discontinuous rock masses can be considered as an equivalent continuum material when the wavelength of the propagating elastic wave exceeds the spatial heterogeneity. However, it is unclear how stress-dependent long-wavelength elastic waves propagate through a repetitive rock-joint system with multiple joints. A preliminary numerical simulation was performed in in this study to investigate long-wavelength elastic wave propagation in regularly jointed rock masses using the three-dimensional distinct element code program. First, experimental studies using the quasi-static resonant column (QSRC) testing device are performed on regularly jointed disc column specimens for three different materials (acetal, aluminum, and gneiss). The P- and S-wave velocities of the specimens are obtained under various normal stress levels. The normal and shear joint stiffness are calculated from the experimental results using an equivalent continuum model and used as input parameters for numerical analysis. The spatial and temporal sizes are carefully selected to guarantee a stable numerical simulation. Based on the calibrated jointed rock model, the numerical and experimental results are compared.
Key Words
    rock mass; elastic wave velocity; quasi-static resonant column test; joint stiffness; DEM simulation
Song-Hun Chong: Department of Civil Engineering, Sunchon National University 255 Jungang-ro, Sunchon, Jeollanam-do 57922, Republic of Korea

Ji-Won Kim and Gye-Chun Cho: Department of Civil and Environmental Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea

Ki-Il Song: Department of Civil Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, Republic of Korea

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