| Rock masses, in general, are not continuous. Therefore, continuum models, such as the Finite Element Method (FEM) and the Boundary Element Method (BEM), usually do not work well when predicting the response of rock masses to loading and unloading. On the other hand, Discrete Element Methods (DEM) are tailored for problems with many discontinuities and large displacements. The Discontinuous Deformation Analysis (DDA) method is a recently developed technique that falls into the family of DEM. Large displacements and deformations are considered under both static and dynamic loadings.; In this thesis, three extensions to the original DDA method have been developed and have been implemented in the original DDA program. First, block contact has been improved by using the Augmented Lagrangian Method instead of the penalty method. Second, a sub-blocking capability has been implemented, whereby blocks are discretized into sub-blocks. A better resolution of stress and strain within each block can then be obtained. Finally, two block fracturing algorithms have been introduced: one for intact blocks and another for sub-blocks. Based on a three-parameter Mohr-Coulomb criterion, intact blocks can be broken into smaller blocks and sub-block fractures are allowed to propagate in a continuous manner across sub-block contacts.; Many engineering problems involving the multiple fracturing of blocky systems, which could not be solved with the original DDA method, can now be studied using the newly enhanced DDA method. The capability of the newly developed DDA program was explored for a variety of two-dimensional engineering problems involving blocky systems: (1) deformation and fracturing of unreinforced masonry shear walls to in-plane loads, (2) modeling of rock-fall including prediction of block trajectory and block fracturing upon impact, (3) modeling of glacier calving at large scales allowing for multiple crevasse propagation and block detachment, (4) prediction of rotational slip in slopes caused by crack propagation, and (5) modeling of the response of blocky rock masses to underground excavation allowing for large block movement and multiple block fracturing.; In general, the new capabilities of the DDA method make it a powerful numerical tool to model the deformation and fracturing of various blocky and non-blocky (continuous) media. |
