An Investigation on the Stability and Resilience of Engineered Slopes Under Simulated Climate Conditions

This thesis investigates the stability of soil slopes subjected to climate scenarios involving rainfall, flooding, and drawdown through experimental and numerical methods. Centrifuge modelling of scaled soil slopes was employed to simulate the effects of seasonal variations and extreme hydrological events, including cycles of wetting, drying, and rapid water level changes. These experiments revealed how rainfall infiltration, surface ponding, and drawdown influence slope deformation and failure mechanisms.
Physical models of the slopes were constructed using sandy kaolin clay mixtures. Pore pressures were monitored in detail during the experiments, and pore pressure contours were subsequently mapped. Particle Image Velocimetry (PIV) was used to monitor sidewall displacements, shear strain, and volumetric strain. The results showed the evolution of shear strains, localised displacements, and erosion patterns. These evaluations indicate that wetting-drying cycles and subsequent flooding significantly affect slope stability along with localised erosion near the slope and toe.
Numerical modelling using GeoStudio (Slope/W and Seep/W) was conducted to replicate experimental conditions during flooding and drawdown. Key soil parameters, including permeability, effective cohesion (c'), angle of friction (φ') were derived from laboratory tests such as permeameter and triaxial. The soil-water characteristic curve (SWCC) was determined from dewpoint and pressure plate tests and fitted using the van Genuchten model. These simulations predicted hydraulic responses and slope behaviour reasonably well, generally aligning with experimental results. Discrepancies appear to be related to choice of strength parameters and issues associated with a lack of pore-fluid coupling in simplified numerical approaches.
Wetting-drying cycles and rapid water level changes are found to destabilise slopes, highlighting the importance of cyclic climate conditions. This research provides a framework for analysing slope behaviour under dynamic hydraulic conditions, helping design and manage slopes in seasonal rainfall and flooding zones.