Problems associated with shrink-swell soils are well known geotechnical problems that
have been studied and researched by many geotechnical researchers for many decades.
Potentially shrink-swell soils can be found almost anywhere in the world especially in
the semi-arid regions of the tropical and temperate climate. Foundation slabs on grade on
shrink-swell soils are one of the most efficient and inexpensive solutions for this kind of
problematic soil. It is commonly used in residential foundations or any light weight
structure on shrink-swell soils.
Many design methods have been established for this specific problem such as
Building Research Advisory Board (BRAB), Wire Reinforcement Institute (WRI), Post-
Tensioning Institute (PTI), and Australian Standards (AS 2870) design methods. This
research investigates most of these methods, and then, proposes a moisture diffusion soil
volume change model, a soil-weather interaction model, and a soil-structure interaction
model.
The proposed moisture diffusion soil volume change model starts with proposing a
new laboratory test to determine the coefficient of unsaturated diffusivity for intact soils.
Then, it introduces the development of a cracked soil diffusion factor, provides a chart
for it, and explains a large scale laboratory test that verifies the proposed moisture
diffusion soil volume change model.
The proposed soil-weather interaction model uses the FAO 56-PM method to
simulate a weightless cover performance for six cities in the US that suffer significantly from shallow foundation problems on shrink-swell soils due to seasonal weather
variations. These simulations provide more accurate weather site-specific parameters
such as the range of surface suction variations. The proposed weather-site specific
parameters will be input parameters to the soil structure models.
The proposed soil-structure interaction model uses Mitchell (1979) equations for
moisture diffusion under covered soil to develop a new closed form solution for the soil
mound shape under the foundation slab. Then, it presents a parametric study by carrying
out several 2D finite elements plane strain simulations for plates resting on a semiinfinite
elastic continuum and resting on different soil mounds. The parametric study
outcomes are then presented in design charts that end with a new design procedure for
foundation slabs on shrink-swell soils.
Finally, based on the developed weather-soil-structure interaction models, this
research details two procedures of a proposed new design method for foundation slabs
on grade on shrink-swell soils: a suction based design procedure and a water content
based design procedure.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2466 |
| Date | 15 May 2009 |
| Creators | Abdelmalak, Remon Melek |
| Contributors | Briaud, Jean-Louis |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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