Linear and non-linear modeling of viscous geo-materials with DDA

Most geo-materials such as rock, concrete, ice show some form of time-dependent behavior. Among all geo-materials, glacier ice shows the most time-dependent response as glaciers deform or creep under their own weight due to gravity. A glacier maintains its mass balance by two processes: accumulation and ablation. Ablation of glaciers occurs by melt, evaporation, and production of icebergs (calving). In very cold environments, calving is the dominant form of loss.; Since the introduction of the discontinuous deformation analysis (DDA) by Shi and Goodman (1984), the DDA method has been extensively developed and used in various engineering disciplines. However, the DDA method still suffers from some limitations and its applications are essentially limited to problems involving linear elastic materials. Therefore, the main objectives of this thesis were two-fold: (i) make the DDA method more widely applicable to engineering problems involving viscous geo-materials, and (ii) provide a better understanding of glacier calving and deformation through numerical simulations with the DDA method.; Two new DDA programs were developed. One of the programs, called DDA02, uses the constant strain triangular element as a basic block. It can be used for the numerical analysis of linear elastic and linear visco-elastic geo-materials. The other DDA program (Non-linear program) uses a five-node quadrilateral element formulation and can be used for the analysis of non-linear viscous incompressible geo-materials.; Numerical simulations of glacier calving using the DDA02 program were performed assuming glacier ice to behave as a linear elastic or linear visco-elastic material. Simple theoretical solutions based on limiting equilibrium were derived to predict glacier calving and were compared with the DDA results. From the results of those analyses, several problems pertinent to the prediction of glacier calving can now be approximately answered and better understood. It was also found that glacier deformation and tensile fracturing are much affected by the viscous characteristics of the ice and the water buoyancy. The relationship between sea water level and the volume of glacier ice breaking off from the original glacier due to calving was numerically investigated and compared with theoretical solutions. The results show that the volume of glacier ice calving off the original glacier increases in a linear fashion as the sea water level increases. (Abstract shortened by UMI.)...