Abstract

Assets such as roads, railways, pipelines and flood embankments are inherently vulnerable to the action of weather and in the long term, climatic change. Their exposure makes them highly susceptible to deterioration during the course of their design life and beyond. The drivers of deterioration are believed to be human (e.g. traffic, maintenance) and environmental (e.g. weather, pollution, burrowing) but the actual deterioration processes are not well understood. Among the weather-driven processes, it is believed that desiccation of the near-surface and the development of cracking can significantly influence the mechanical, hydrological and thermal behaviour of geotechnical structures primarily by impacting the transmission of water between the atmosphere and soil. Enhanced infiltration during rainfall events can potentially lead to rapidly elevated pore water pressures and reduced shear strength and is widely cited as the strength reduction mechanism behind the wide spread failure of infrastructure slopes. This paper describes the development of a pseudo-discrete continuum Finite Difference model and its application to investigate the influence of soil properties (including elastic modulus, hydraulic conductivity and soil-water retention) on the desiccation process and eventual crack initiation and propagation behaviour. The generation of a desiccated crust typified by highly negative pore pressures and increasingly disintegrated texture is demonstrated. The influence of projected higher drying rates and seasonal drying-wetting cycles (that could result from climate change) on crack pattern development is investigated to gain an understanding of progressive deterioration. This points towards the potential for increased future deterioration rates of geotechnical infrastructure.

Highlights

  • Geotechnical assets are fundamental to the delivery of critical services, such as roads, railways, pipelines and flood protection structures and are characterised by a number of common features

  • The significance of this work is that the susceptibility of engineering soils to cracking related deterioration may be better understood in the context of current and future climatic conditions

  • The main difference is in the distribution of cracking across the mesh – the removal of any stress relief effect at the lateral boundaries results in crack distribution being solely governed by tensile strength heterogeneity

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Summary

Introduction

Geotechnical assets are fundamental to the delivery of critical services, such as roads, railways, pipelines and flood protection structures and are characterised by a number of common features. The soil component of the asset is materially highly heterogeneous, meaning that its current state (relative to the required design performance) is unknown, as is its rate of deterioration This means that our most critical infrastructure is in an unknown state of repair, and there is currently little understanding of the rate of deterioration of these assets and how this may be affected by extreme weather events or climate change. The significance of this work is that the susceptibility of engineering soils to cracking related deterioration may be better understood in the context of current and future climatic conditions This understanding can be used to determine the implications of both extreme and repeated seasonal drying on the deterioration of geotechnical infrastructure. This has the potential to be used to quantify the increase in investment required to maintain the long-term performance of assets

Material
Numerical model
Constitutive parameters
Basal interface properties
Crack interface properties
Hydrological properties
Drying boundary condition
Model behaviour
Mechanical boundary sensitivity
Hydrological parameter sensitivity
Constitutive property sensitivity
Sensitivity to tensile strength development
Findings
Conclusions
Full Text
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