| Discrete element methods (DEMs) are a family of related numerical procedures for solving problems that exhibit gross discontinuous behavior. Many of these methods are capable of analyzing multiple interacting bodies undergoing large displacements and rotations. These methods are suitable for studying several types of geotechnical problems involving granular materials and rock masses, which are intractable with conventional methods, based on continuity assumptions.; Even though DEMs have been used for about twenty years and interest in the use of these techniques is increasing rapidly, the methodology has not progressed significantly and most DEMs for geomechanical materials still require unrealistic idealizations. In fact, most models for granular materials still represent individual particles as two-dimensional circular disc elements. Methods for the analysis of jointed rock are still unable to adequately model the deformability of the individual blocks, and cannot incorporate the effects of water pressures along the joints. In all these methods, interactions among elements are specified through the same point contact models, which are unrealistic in many applications. In addition, there has been no significant improvements in the schemes for detection of contacts, which is the most expensive part of DEM analysis.; In this research, a series of two-dimensional and three-dimensional DEMs have been developed to model the discontinuous behavior of granular materials and rock masses. A total of five DEMs were proposed, along with new block models, contact models, and effective contact detection procedures and data structures, which allow analyses with large numbers of blocks. Granular materials have been represented by large numbers of rigid particles of random shapes and sizes. Rock masses have been modeled as assemblages of multiple deformable rock blocks interacting through deformable joints. The considerable experience gained in the finite element method to model continuum has been utilized to model the deformability of individual blocks. Realistic distributed contact models have been proposed. Discrete methods have been developed, which model the discontinuous character of water flow through rock masses, and the effects of water pressures along rock joints. Individual rock blocks have been assumed to be impervious. Fluid flow has been assumed to occur through the joints. The proposed hydromechanical model includes the coupling between flow and deformation. |
