GCG has investigated the behaviour and potential applications of Capillary Barrier Systems (CBSs) for suction control in geotechnical engineering. CBSs are engineered systems consisting of a finer-grained upper layer (F.L.) placed over a coarser-grained lower layer (C.L.), which is installed above the natural ground. Their primary function is to reduce or prevent rainwater infiltration into the underlying soil, thereby preserving soil suction during rainfall events.
The effectiveness of a CBS relies on the capillary barrier effect at the interface between the F.L. and C.L., which arises from the contrast in their unsaturated hydraulic properties. This capillary break causes rainwater to accumulate in the upper layer, where it is subsequently removed through evapotranspiration and lateral drainage.
To enhance the modelling of CBS performance, we first developed and implemented advanced constitutive models that accurately represent the hydraulic behaviour of unsaturated soils. We then conducted a series of laboratory column infiltration tests and numerical simulations to optimise CBS design and configuration. Finally, we performed advanced numerical analyses to evaluate the use of CBSs for suction control and the mitigation of rainfall-induced slope instability. These analyses employed sophisticated 2D thermo-hydraulic, multiphysics, and multiphase finite element simulations, incorporating complex soil-atmosphere interactions and unsaturated soil conditions.
Our study concluded that, compared to traditional concrete-based solutions and conventional soil covers, CBSs offer advantages in cost, durability, and the potential use of recycled, low-cost materials. As such, CBSs represent sustainable and resilient geotechnical solutions adaptable to a range of climatic conditions—an increasingly important consideration in the context of climate change.
Publications
Scarfone, R., & Wheeler, S. J. (2023). Capillary Barrier Systems for prevention of rainfall-induced slope instability. In Proceedings of the BGA Georesilience 2023 Conference, Cardiff, United Kingdom, 28th – 29th March 2023.
Scarfone, R., Wheeler, S. J., & Smith, C. C. (2022). Capillary barrier systems for prevention of rainfall-induced slope instability. Ground Engineering, March 2022.
Scarfone, R., Wheeler, S. J., & Smith, C. C. (2022). Numerical modelling of the application of capillary barrier systems for prevention of rainfall-induced slope instability. Acta Geotechnica, 1-24.
Scarfone, R., & Wheeler, S. J. (2022). Analytical and numerical modelling of air trapping during wetting of unsaturated soils. Acta Geotechnica, 1-15.
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