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Master's Dissertation
DOI
10.11606/D.18.2011.tde-01122011-100235
Document
Author
Full name
Osvaldo Paiva Magalhães Vitali
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2011
Supervisor
Committee
Giacheti, Heraldo Luiz (President)
Bernardes, George de Paula
Mio, Giuliano de
Title in Portuguese
Desenvolvimento de um sistema para realização de ensaios sísmicos down-hole em conjunto com o CPT
Keywords in Portuguese
Down-hole
Ensaio sísmico
Ensaios de campo
Investigação do subsolo
Ondas S
SCPT
Abstract in Portuguese
Quando ocorrem solicitações dinâmicas nos solos, torna-se indispensável a determinação do módulo de cisalhamento máximo (Go) para elaboração de projetos de Engenharia Geotécnica. Este parâmetro pode ser determinado a partir da velocidade de propagação das ondas S (Vs). Em campo, os ensaios mais empregadas para determinação de Vs são o cross-hole e o down-hole. O down-hole tem sido bastante empregado com a incorporação de geofones em ponteiras de piezocone. Esse ensaio tem se mostrado uma maneira rápida, econômica e muito confiável para determinação de Go, apresentando resultados consistentes com os obtidos no ensaio cross-hole. O objetivo deste trabalho é o desenvolvimento de um sistema para realização do ensaio sísmico down-hole e sua implantação. Inúmeros ensaios foram realizados no campus da Universidade Estadual Paulista, em Bauru/SP a fim de testar os procedimentos para execução do ensaio, os equipamentos utilizados e as técnicas de interpretação, onde se observou que a manutenção do eixo de vibração dos geofones paralelo a direção de aplicação do golpe foi o fator que mais influenciou na qualidade dos sinais. Para analisar a resposta dos geofones instalados na ponteira desenvolvida, realizaram-se ensaios em laboratório, onde se verificou que os geofones apresentavam resposta idêntica ao dos acelerômetro de referência. Por fim, foram realizados ensaios em três campos experimentais no interior do Estado de São Paulo, onde estão disponíveis resultados de ensaios cross-hole e ensaios down-hole realizados com equipamentos comerciais. Os resultados obtidos com o sistema desenvolvido nestes campos permitiram validar o sistema desenvolvido.
Title in English
Seismic testing down-hole in conjunction with CPT
Keywords in English
Down-hole
Field tests
SCPT
Seismic test
Shear waves
Subsurface investigation
Abstract in English
In the design stages of geotechnical engineering of a given project, it is imperative to ascertain the maximum shear modulus (Go) of those soils experiencing dynamic loads. One common method to determine Go is to measure shear wave velocity. Most field experiments are the cross-hole and down-hole tests to determine the velocity of shear waves. The downhole test has been widely used in conjunction with geophones placed behind the tip of piezocones. The down-hole test has proven to be a fast, economic, and very reliable method to determine Go, it has produced data consistent with results obtained in cross-hole tests. The objective of this work is to present a comprehensive system for the down-hole test, which includes its implementation, execution, and the interpretation of data collected. Several tests were performed at the campus of Universidade Estadual Paulista, UNESP, in Bauru, S.P. The objective of those experiments was to test the execution procedures and method of interpretation. It was observed the quality of the results obtained was chiefly dependent on maintaining the axis of vibration of the geophones parallel to the direction of application of the original blow. The analysis of the response by the geophones installed at the tip of the cone included experiments performed at the laboratory, where it was observed that the geophones responded identically to those accelerometers used as reference. Further, downhole experiments using system proposed here were performed in three experimental research sites of the state of São Paulo. The objective was to compare results to the data available in literature, which were obtained using commercial SCPT equipment and cross-hole tests. The down-hole testswere performed within the guidelines of the system proposed here and the results of the experiment served to corroborate the suitability of the developed system.
 
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Publishing Date
2011-12-01
 
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