Título: | SETTLEMENT ANALYSIS OF AN EMBANKMENT ON VERY SOFT SOIL IN BARRA DA TIJUCA | |||||||
Autor: |
CHRISTIANO FARIA TEIXEIRA |
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Colaborador(es): |
SERGIO AUGUSTO BARRETO DA FONTOURA - Orientador SANDRO SALVADOR SANDRONI - Coorientador |
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Catalogação: | 19/MAR/2013 | 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=21333&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=21333&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.21333 | |||||||
Resumo: | ||||||||
This work presents a settlement analysis of an embankment built on a very
soft soil deposit in Barra da Tijuca (Baixada de Jacarepaguá), which is located in
Rio de Janeiro’s coast. The geotechnical profile shows a very soft soil with
thickness reaching 17 m, with Nspt equal 0. The embankment was built in stages and its
settlements were accelerated with prefabricated drains. The construction lasted
about 1,5 year and was monitored by means geotechnical instrumentation. Field
and laboratory test programs were carried out to define the geotechnical
characteristics of the soil. Ten samples were collected from two vertical boreholes
before any loading was applied to the soil. To avoid disturbance, each stage of
sample process, from sampling to specimen preparation, was conducted with
special procedures. Tests have been carried out both in undisturbed (vertical and
horizontal directions) and completely disturbed conditions. The specimen
preparation procedures are described in detail. Conclusions considered only the
results of tests conducted on specimens with excellent quality. The in-situ tests
were performed in vertical boreholes next to boreholes where the undisturbed
samples were collected and in the same location in which geotechnical instruments
group were installed. The analysis of the field and laboratory tests and
instrumentation data revealed the existence of two very soft soil layers exhibiting
distinct characteristics which are separated by a continuous sand lens. The upper
soil layer (from surface down to about 5 m depth), that was probably formed after
an unloading geological period of the underlying layer, is characterized by low
effective in situ stresses. The underlying soil is also under low in-situ effective
stresses, but with a preconsolidation pressure characterized by the difference s’p -
s’v0 25 kPa (constant with depth). A correlation between OCR (from
consolidation tests) and Su/sv0 ratio (from vane and CPTU tests) for similar soils
has been updated. The high compressibility of soils was confirmed by the embankment instrumentation data. Ca/Cc values, higher than usual for most known
soils, were found. Practical relationships have been updated to describe the
permeability of the deposit. Soil consolidation coefficients were estimated in
different ways and values, even though have showed large difference (up to ten
times), did not showed tendency when laboratory or field (tests and instrumentation
data) values were compared. Disturbance affected the permeability and
compressibility (primary and secondary) characteristic of the soils of both layers,
but its effects were more severe in the underlying layer. A numerical prediction, in
which a creep-soft-soil model was used and parameters obtained from the
laboratory tests were considered, lightly overestimated the embankment settlements
with time.
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