Numerical modelling of complex slope deformations
This thesis presents the analysis of complex slope deformations through the application of numerical modelling techniques. Complex slope deformations, in this thesis, include cases where the use of more conventional analytical tools such as limit equilibrium techniques or the use of empirical criteria are not readily applicable. Such a scenario often results from adverse geological and environmental conditions or from human activity. Examples of complex slope deformations are the influence of underground mining on a slope, or situations where rigid jointed rocks overly relatively weak layers. The use of numerical modelling techniques, both continuum and discontinuum, in the analysis of slope stability problems has increased rapidly in the last decade and proved valuable in the analysis of complex geomechanical problems. Two numerical modeling programs FLAC (Fast Lagrangian Analysis of Continua) and UDEC (Universal Distinct Element Code) were used in this thesis. Three main groups of problems were investigated: (1) The analysis of deformation associated with rigid jointed rocks overlying relatively weak layers including a case study involving deformation taking place in the foundation of the Spis Castle in Slovakia. It was demonstrated that the type of deformation in such cases depends on the strength, deformability and thickness of the weak layer as well as the jointing pattern of the overlying rocks. It was shown, that the deformations at Spis castle are governed primarily by the presence of a weak, plastic "creep zone" under the base of the travertine blocks on which the castle is founded. (2) The analysis of toppling deformation in a weak rock slope comprising several lithostratigraphic units at the Luscar Mine, Alberta. It was found that the instability mechanism in the initial phase was flexural toppling, confined to a distinct quasi-linear failure surface which provided the shear plane for subsequent sliding movement. A prediction of slope stability for a planned mine extension in the same pit was made, thereby determining "safe excavation limits". (3) The analysis of interaction between underground mining and slope instability. The analyses of various slope deformation mechanisms that can be induced by underground mining are presented. The analysis of the Frank Slide in southwestern Alberta illustrated the critical role of underground mining at the base of the Turtle Mountain on triggering the final slope failure. The analyses present within this thesis demonstrate the application of numerical modelling techniques in the characterization of complex slope deformations. New interpretations of existing failure mechanisms were presented in the case of the Frank Slide, and improved understanding of the failure mechanism and slope deformation were gained in the Luscar Mine and Spis Castle case studies. Furthermore, hypothetical modelling studies relevant to underground mining and block-type deformations allow an increased understanding of complex slope deformations.
DegreeDoctor of Philosophy (Ph.D.)
Copyright DateMarch 1997
Fast Lagrangian Analysis of Continua
slope deformation - mathematical modelling
Universal Distinct Element Code