Physical and numerical study of soil-atmosphere and soil-atmosphere-structure interactions during drying events

Extreme, extended wet and dry seasons have become more frequent in different parts of the world as the result of global warming. The intensity of these events increases the adverse effects that cyclic hydraulic and thermal fluxes have on the performance of geotechnical structures, especially on the...

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Autores:: Granados Rueda, Jaime Eduardo

Tipo de recurso:: Doctoral thesis

Fecha de publicación:: 2024

Institución:: Universidad de los Andes

Repositorio:: Séneca: repositorio Uniandes

Idioma:: eng

Description
Summary:	Extreme, extended wet and dry seasons have become more frequent in different parts of the world as the result of global warming. The intensity of these events increases the adverse effects that cyclic hydraulic and thermal fluxes have on the performance of geotechnical structures, especially on the mechanical response of shallow structures. To account for the effects of climate fluctuations, the design, construction, and stability analysis of existing and new geotechnical projects need to implement methods to evaluate soil-atmosphere and soil-atmosphere-structure interactions. This may be achieved using physical and numerical methods that represent the water and heat transfer mechanisms and the thermo-hydro-mechanical (THM) response of unsaturated soils subjected to variable atmospheric conditions and structural loading. This study combined physical testing and numerical methods to evaluate the effects of soil-atmosphere interactions on the hydraulic and thermal fluxes and THM response of unsaturated soils. The first part of this study was experimental and focused on the evaporation process from soil-atmosphere interfaces represented by thin soil layers. A wide range of atmospheric conditions including temperature, relative humidity, irradiance, and wind velocity were imposed on soil surfaces of various textures to identify the key atmospheric parameters and soil properties that control evaporation. Based on the experimental results, an empirical model was proposed to estimate evaporation rates from soil-atmosphere interfaces. The model was expressed as a function of the relative humidity and wind velocity of the air measured near the soil surface, the mean suction of the soil-atmosphere interface, and the soil thickness. These were found to be the most significant atmospheric and soil parameters during evaporation. In the second part of this study, a coupled THM numerical model for soil-atmosphere interaction was developed. The model was written based on the laws of mass and thermal conservation and principles of thermodynamics and unsaturated soil mechanics. The Partial Differential Equations (PDE) that govern the flow of water in liquid and vapor phases and heat transfer were solved using a mixed Explicit-Implicit Finite Difference Scheme. The mechanical response of the soil was coupled to the hydro-thermal fluxes by means of changes in soil suction. The numerical model was validated for drying atmospheric conditions using the results of the experimental program. In the third part of this study, the soil-atmosphere interaction model was adapted to evaluate soil-structure interactions of a lightly-loaded structure subjected to variable atmospheric conditions. The numerical model included the analysis of soil-structure strain compatibility due to structural loading and soil shrinkage or swelling. The distribution of compressive stresses, relative displacements, and potential wall damage were also evaluated. The results of the experimental program and numerical modeling may be used to evaluate the behavior of different types of geotechnical structures under variable climatic conditions.

Physical and numerical study of soil-atmosphere and soil-atmosphere-structure interactions during drying events

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