Abstract:
|
The main aim of this thesis was to interpret the natural anisotropy of a soil using
new experimental transducers called bender and extender elements in a Triaxial Cell
Apparatus. Firstly a specimen had to be prepared with a desired relative density using a
technique called Pluviation. Secondly a tricky procedure had to be overtaken in order to
install and protrude the transducers in the sample properly. The third step was to set up
the Triaxial Cell Apparatus and apply an isotropic pressure to the soil sample. That
done, a good interpretation of the signal waves passing through the sample in either
vertical or horizontal directions had to be well understood. The final step is to apply
some wave formulae in order to asses some results.
All the data obtained was then compared with recent research done by Dr Tarek
Sadek (Bristol, 2007) as a PhD student at the University of Bristol. The degree of
anisotropy, the elastic shear and constrained modulus in the field of very small strains
were the data studied and compared in detail.
One of the most important difficulties encountered was to set up properly the
whole device bearing in mind that for the horizontal transducers there was no space
already done so a new development needed to be invented. Some big troubles were
created but thanks to some advice from my supervisors and from the technician they
were overtaken.
Another issue found was how to interpret wave output data because first of all
its signal some times was particularly not clear and secondly because there was not an
objective method to assess it without doubt. Therefore, some wave theory has been
explained by the author as well as some improvements to try to achieve the best
interpretation with the minimum subjectivity. |