Hybrid finite-discrete element modelling of asperity degradation and gouge grinding during direct shearing of rough rock joints

Abstract

A hybrid finite-discrete element method was implemented to study the fracture process of rough rock joints under direct shearing. The hybrid method reproduced the joint shear resistance evolution process from asperity sliding to degradation and from gouge formation to grinding. It is found that, in the direct shear test of rough rock joints under constant normal displacement loading conditions, higher shearing rate promotes the asperity degradation but constraints the volume dilation, which then results in higher peak shear resistance, more gouge formation and grinding, and smoother new joint surfaces. Moreover, it is found that the joint roughness affects the joint shear resistance evolution through influencing the joint fracture micro mechanism. The asperity degradation and gouge grinding are the main failure micro-mechanism in shearing rougher rock joints with deeper asperities while the asperity sliding is the main failure micro-mechanism in shearing smoother rock joints with shallower asperities. It is concluded that the hybrid finite-discrete element method is a valuable numerical tool better than traditional finite element method and discrete element method for modelling the joint sliding, asperity degradation, gouge formation, and gouge grinding occurred in the direct shear tests of rough rock joints.

Development of a GPGPU‐parallelized hybrid finite‐discrete element method for modeling rock fracture

“…In addition, a number of operations such as pan, rotation, zoom, various viewports in perspective and/or orthographic modes, and slideshow are developed to manipulate the numerical models and calculated results (see Liu et al for further details). The code has been successfully employed in the simulation of the fracture process in various geotechnical engineering problems . Because of the nature of sequential programming, its main application was limited to small‐scale 2D problems using a relatively rough mesh.…”

“…The code has been successfully employed in the simulation of the fracture process in various geotechnical engineering problems. [37][38][39][40] Because of the nature of sequential programming, its main application was limited to small-scale 2D problems using a relatively rough mesh. To overcome this limitation, the parallel programming scheme using the GPGPU accelerator controlled by CUDA C/C++ is implemented into the Y-HFDEM 2D IDE through this study.…”

“…Several attempts have been made to actively extend the Y code, such as Y‐GEO, IRAZU, Solidity, HOSS with MUNROU, and Y‐Flow . In addition, the authors also developed the Y‐HFDEM IDE (integrated development environment) . The principles of all of the hybrid FDEM codes are based on continuum mechanics, the cohesive zone model (CZM), and contact mechanics, which make the codes very computationally expensive.…”

“…[32][33][34][35][36] In addition, the authors also developed the Y-HFDEM IDE (integrated development environment). [37][38][39][40] The principles of all of the hybrid FDEM codes are based on continuum mechanics, the cohesive zone model (CZM), and contact mechanics, which make the codes very computationally expensive. Therefore, developing a capable parallel computation scheme is important for handling large-scale problems with a massive number of nodes, elements, and contact interactions.…”

“…[20][21][22] Thus, further studies are required to develop the GPGPU-based hybrid FDEM. In this regard, we have developed free research code*, Y-HFDEM IDE, [37][38][39][40] and recently parallelized it using GPGPU with CUDA C/C++. Moreover, it is desirable to fully describe any newly implemented GPGPU-based code because the implementation of GPGPU-based codes differs from that of CPU-based sequential codes.…”