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Master's Dissertation
DOI
10.11606/D.18.2018.tde-25062018-135932
Document
Author
Full name
Guilherme Izidorio Davies
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2000
Supervisor
Committee
Vilar, Orencio Monje (President)
Giacheti, Heraldo Luiz
Marinho, Fernando Antonio Medeiros
Title in Portuguese
Análise e modelagem do comportamento colapsível de um solo arenoso
Keywords in Portuguese
Ciclos de umedecimento e secagem
Colapso
Ensaio edométrico com sucção controlada
Ensaio triaxial
Modelos elasto-plásticos
Abstract in Portuguese
Muitas são as pesquisas que avaliam as variáveis intervenientes no colapso dos solos: contudo, pouco tem sido publicado a respeito da influência da trajetória de ciclos de umedecimento e secagem, no comportamento colapsível do solo, e do colapso em condições de carregamento triaxial. O presente trabalho tem como objetivo estudar o colapso de um solo arenoso, típico da região centro-oeste do Estado de São Paulo, frente a tais variáveis através de ensaios edométricos convencionais, edométricos com controle de sucção e triaxiais. Dos ensaios edométricos convencionais caracterizou-se o colapso sob vários níveis de tensão, determinando assim a sobrecarga de inundação que causa máximo colapso. Nos ensaios de compressão triaxial, cada amostra foi inundada sob um determinado estado de tensão, caracterizado pela relação σ13. Nestes ensaios foi observado que as deformações volumétricas são dependentes da tensão confinante e da relação σ13, e que as deformações axiais por colapso são menores que as medidas nos ensaios edométricos convencionais. Nos ensaios edométricos com sucção controlada verificou-se que o valor inicial da sucção apresenta influência no valor do colapso total. Quanto aos ciclos de umedecimento e secagem, o solo sofreu colapso insignificante quando a sucção foi reduzida a um mesmo valor pela segunda vez. Os resultados experimentais dos ensaios edométricos com sucção controlada foram então modelados de acordo com o modelo de ALONSO et. al, (1990), e as adaptações a esse modelo propostas por FUTAI (1997) e MACHADO (1998), verificando-se a capacidade de cada formulação em representar matematicamente o comportamento colapsível do solo estudado.
Title in English
Analysis and modeling of the collapse behavior of a sandy soil
Keywords in English
Collapse
Edometric test with controlled suction
Elasto-plastics models
Humidity and dry cycles
Triaxial test
Abstract in English
There are many researches that evaluate and discuss the factors which interfere in the collapse of soils. However, not many have been published regarding the influence of the cycles of wetting in the collapsible behavior of the soil, and neither have collapse strains under triaxial load. The present work deals with the collapse behavior of a sandy soil, typical from the center-west of the State of São Paulo, considering the aforesaid aspects and using conventional oedometer, suction controlled oedometer and triaxial compression tests. In conventional oedometer tests, the influence of overburden stress on the induced wetting on collapse strains was characterized. Collapse strains were also measured in triaxial compression tests, varying the ratio of principal stress (σ13) when the samples are inundated. It was observed that collapse volumetric strains are dependent on confining stress and on σ13, and that, axial and radial strains are related to the ratio of σ13. The axial collapse strains observed in triaxial compression tests were shown to be lower than the ones measured in conventional oedometer tests. In controlled suction tests, the amount of collapse strains under gradual suction reduction was studied including the influence of suction reversals. It was noted that the initial suction influences the amount of collapse strains, and that, in the cycles of wetting and drying, the strains after the second cycle tended to be negligible. Experimental results from suction controlled oedometer tests were modeled through the model by ALONSO et. al. (1990) and by the adaptations to this model proposed by FUTAI (1997) and MACHADO (1998).
 
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Publishing Date
2018-06-25
 
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