Modelling soil dewatering and recharge for cost-effective and climate resilient infrastructure

In geotechnical infrastructure, it is essential to understand the processes involved in detail, both for controlling groundwater levels and pore pressures during construction, and for potentially managing soil water content to mitigate extreme cycles of seasonal wetting and drying caused by climate change.

There are particular issues that require a better understanding of soil water entry and exit processes, including:

• the depressurisation of relatively low permeability soils, particularly those comprising grains of mixed mineralogy and typical size. What is the effect of applying a vacuum at the soil / well boundary, in terms of additional depressurisation in the soil? How is this distributed within the soil? How would partial or zonal desaturation affect the behaviour?
• the recharge of soils and waste landfills, where clogging of the soil pores by impurities or the movement of fine particles can be an issue.
• Combining the above points, what is the feasibility of controlled water abstraction or injection to mitigate vegetation / climate induced seasonal changes in water content that lead to major shrink/ swell issues with clay embankments in particular. How would this be affected by zones of preferential flow and / or air entry?

In this project we will develop new mathematical models of soil wetting (water injection) and dewetting (water abstraction) that will enable:

• development of new understandings of what in particular influences air entry and water exit effects into and from fully saturated soils
• investigation of the microscale processes the influence soil wetting, and how these may be modified on the pore scale
• taking into account the role plants play in these processes
• assessment of the feasibility of engineered mitigation of the effects of climate induced water cycles on the wetting and dewetting of volume-sensitive soils