Fully dynamic coupling of the boundary and discrete element method for the simulation of large-scale geotechnical problems

This thesis introduces novel coupling schemes between the Discrete Element Method (DEM) and the Boundary Element Method (BEM) for dynamic multi-scale modelling, effectively addressing continuous and discontinuous media in one, two, and three dimensions within finite and infinite domains. It begins by establishing a theoretical foundation with a novel monolithic time integration method for 1D wave propagation, demonstrating the feasibility of BEM–DEM coupling. Advancing to two dimensions, the research presents a direct interface-based method, harmonising the DEM’s capability to model discontinuous behaviours like fracturing with the BEM’s proficiency in evaluating far-field effects. A key innovation of this work is the development of an efficient multi-scale staggered coupling approach. This method significantly enhances computational efficiency and accuracy, especially in simulating complex dynamics such as seismic wave propagation. The thesis reaches a high point with the extension of the coupling technique to 3D problems, integrating spherical discrete elements and bilinear quadrilateral boundary elements. This novel approach overcomes previous limitations in representing discontinuities within infinite domains and is validated through comprehensive numerical experiments. Overall, it is hoped this thesis represents a significant leap forward in the field of multi-scale analysis, providing robust, efficient, and accurate methods for coupling BEM and DEM. These techniques pave the way for addressing complex dynamic problems in various scientific and engineering domains, thus contributing substantially to the field of computational mechanics.