GPGPU-based 3-D hybrid FEM/DEM for numerical modelling of various rock testing methods

In the field of geotechnical engineering, the number of applications of combined/hybrid finite-discrete-element method(HFDEM) to both the lab-scale and field-scale problems has increased recently. In author’s research group at universityof Tasmania, 2-D/3-D HFDEM code has also been successfully developed [e.g. Liu et al. 2015, Int. J. Geotech. Eng.9:115-131] and applied to some geotechnical engineering problems such as rock blasting, fracture processes in a seriesof lab-scale rock testing methods and asperity degradation and gouge grinding during direct shearing of rough rock joints.However, since the HFDEM code was implemented by sequential programming, its main application mentioned abovewas limited to 2-D problems owing to the computationally expensive nature of HFDEM. To overcome this situation, theparallel programming scheme using “general-purpose-graphic-processing-unit (GPGPU)” and “CUDA (Compute UnifiedDevice Architecture) C” was recently incorporated into the HFDEM code and significant speed-up has been achieved.This paper briefly describes the theory and newly incorporated features of the GPGPU-based HFDEM code along withsome important issues which have not been addressed clearly in the previous publications using HFDEM. Then, this paperdemonstrates some examples of 3-D numerical modelling of rock fracture process using various lab-scale rock testingmethods such as quasi-static Brazilian test, quasi-static uniaxial compression test, dynamic Brazilian test using SplitHopkinson Pressure Bar (SHPB) apparatus. Through these demonstrations, the applicability of the newly developed 3-DHFDEM code is shown