Título: | DEVELOPMENT OF A DIFFUSION CELL FOR UNSATURATED SOILS | ||||||||||||||||||||||||||||
Autor: |
ANA CRISTINA MALHEIROS GONCALVES CARVALHO |
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Colaborador(es): |
TACIO MAURO PEREIRA DE CAMPOS - Orientador EURIPEDES DO AMARAL VARGAS JUNIOR - Coorientador |
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Catalogação: | 01/NOV/2001 | Língua(s): | PORTUGUESE - BRAZIL |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||||||||||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=2063&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=2063&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.2063 | ||||||||||||||||||||||||||||
Resumo: | |||||||||||||||||||||||||||||
In the design of waste disposal facilities and evaluation
of groundwater and soil contamination by organic and
inorganic species, it is essential a knowledge of the
mechanisms of transport of the contaminants. There are two
basic processes in the transport of solutes: advection and
hydrodynamic dispersion.Advection is the process by which
moving groundwater carries with it dissolved solutes. The
amount of solute being transported depends on its
concentration in the groundwater, on the volume of
groundwater flowing, and on the groundwater velocity. The
hydrodynamic dispersion mechanism involves mechanical
dispersion and diffusion. As solutes are carried through
porous media, the process of dispersion acts to dilute the
solute and reduce its concentration. Diffusion, is the
process by which both ionic and molecular species dissolved
in water move from areas of higher concentration to areas
of lower concentration, even in the absence of groundwater
flow.Advective-diffusive transport through unsaturated
media is somewhat more complicated than for saturated
soils. In this case, the transport parameters may vary both
in space and in time. Hence, the determination of such
parameters in laboratory should be performed as close as
possible to in situ conditions.The processes by which the
substances move through porous media can be expressed
through mathematical models. They are based on the
integration of the advection-dispersion equation using
specific boundary conditions for the system of interest.
However, their applicability has been often limited due to
the lack of reliable parameters obtained experimentally.
This thesis seeks to fulfil the gap between numerical
modelling and experimental studies. A new diffusimeter has
been developed to measure the diffusion coefficient in
unsaturated soils. It combines the single reservoir method,
proposed by Rowe et al. (1988), with the osmotic control
technique. Tests were performed under suction values
ranging from 0 to 500kPa. Sodium chloride and potassium
chloride were used as solutes diffusing through a compacted
inert sample prepared in the laboratory. The results
obtained indicated that the new proposed technique worked
quite well, being however recommended an improvement in the
system of suction control through the use of more precise
instrumentation.
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