| The inherent complexities in the mechanical behavior of rock masses come from the discontinuous nature of rock masses, which exist in many forms such as fissures, cleavages, beddings, joints, and even faults. The scale effects of jointed rock masses, rock fracture propagation, and the effects of groundwater are postulated to be paradigmatic components of these complexities, and a proper incorporation of these components into an analysis is crucial to construction and design involving jointed rock masses. This study presents the development of a unified numerical framework based on the numerical manifold method (NMM) for modeling these three complexities in jointed rock masses.; In this study, the modeling of scale effects was tackled by a proposed two-scale approach through the use of the primary joint set and the secondary joint set. The primary joint set, which has wider joint spacing, was modeled as physical discontinuities to preserve the rock mass kinematics, while the secondary joint set, which has narrower joint spacing, was modeled as an equivalent continuum. The modeling of fracture propagation was based on the theory of linear elastic fracture mechanics. The stress intensity factors were computed by both displacement-based and energy-based methods. The maximum stress criterion was employed for fracture propagation. The modeling of fracture propagation was accomplished within the NMM by merely changing the physical mesh to describe the evolving cracks. Furthermore, the modeling of the effects of groundwater on joints was introduced by considering water as pressure acting on the joint surface.; The methodology proposed in this study has been examined through the calculation of a number of numerical examples and comparison with available analytical and experimental results. Application examples were also provided to demonstrate the applicability of the developed numerical framework. The results obtained show that: (1) the proposed two-scale concept has the potential for describing very complex behavior of jointed rock masses and may be employed in assessing large-scale rock mass strength and the problems of slope stability with many joints; (2) the study explores the simplicity of modeling fracture propagation by merely changing the physical mesh to describe evolving cracks, which alleviates the difficulty of the requirement of the spatial discretization that accommodates the changing topology of a problem domain; and (3) the ability to capture an entire process of a slope failure evolution is demonstrated from an initial phase of a tensile crack on a slope surface, to the intermediate phase of forming a failure surface, and to the final phase of the post-failure of a failed soil block sliding down the slope. |
