Investigation of the hydraulic regime of a desiccated slope under both natural and simulated environmental conditions

Abstract

Deterioration within desiccated, clay infrastructure embankments can originate from two processes: (A) preferential flow through cracks allowing deeper and faster propagation of wetting fronts, and (B) microstructural degradation, reducing soil water retention capacity. These processes are interrelated, and together act to increase surface layer exposure to intense mechanical weathering and therefore, risk of asset failure. Desiccation induced deterioration is set to intensify under future climate change projections, heightening the need to understand how these processes develop within, and deteriorate, embankment fill over time. To address this, long-term hydrological and desiccation crack monitoring of a large-scale slope, constructed within an outdoor lysimeter, has been carried out under both natural, and simulated, climatic conditions. Initial findings illustrate a highly desiccated slope has the capacity to accept a large volume of storm rainfall prior to crack closure. This volume is set to increase due to the progressive aggregation and reduction in SWR behaviour observed within the slope. The importance of antecedent conditions, both in terms of crack geometry and initial degree of saturation, at the onset of rainfall, additionally proved important as it controls the depth and magnitude of VWC change in the slope. Continued monitoring of the slope will aid our understanding of the temporal evolution of these deterioration processes.