Estudo da compressibilidade e da colapsibilidade de um perfil do subsolo por meio do DMT
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Data
2021-12-21
Autores
Rodrigues, André Luís de Carvalho
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As deformações verticais de um solo devido à carregamentos típicos, como em fundações superficiais, podem influenciar o desempenho de edificações. Elas podem causar grandes prejuízos quando não previstas adequadamente, em especial em solos colapsíveis. O estudo do colapso tem sido feito em laboratório, com ensaios de compressão confinada em amostras indeformadas com e sem inundação. O Dilatômetro Plano (DMT) tem sido utilizado para a investigação do subsolo com bons resultados para a estimativa de recalques de fundações. Poucos estudos têm sido feitos para avaliar sua aplicabilidade em solos não convencionais, como os colapsíveis. Neste trabalho avaliou-se o emprego do DMT para a previsão da curva tensão-recalque de fundações superficiais e seu uso para identificar solos colapsíveis. O estudo foi realizado para o solo do Campo Experimental da Unesp de Bauru, onde existe uma areia fina pouco argilosa, porosa e colapsível. Utilizou-se um dispositivo acoplado ao DMT para inundar o solo in situ e obter resultados na condição natural e inundada. Previsões das curvas tensão-recalque, bem como os valores de recalque para a carga de trabalho foram comparados com resultados de provas de carga em placa nestas duas condições. Dois critérios para identificação de solos colapsíveis foram aplicados e adaptações foram sugeridas para eles serem utilizados com resultados de ensaios DMT. O dispositivo acoplado ao DMT e o procedimento proposto para gerar dados na condição natural e inundada in situ é um recurso promissor para avaliar o efeito da sucção no comportamento in situ do solo. Também tem potencial para ser empregado para identificar a presença de solos colapsíveis, numa abordagem qualitativa e preliminar de investigação do subsolo.
The vertical deformations of a soil due to typical loads, as in shallow foundations, can influence the performance of buildings. They can cause great damage when not properly predict, particularly in collapsible soils. The study of collapse has been carried out in laboratory, with confined compression tests on undisturbed samples with and without flooding. The Flat Dilatometer (DMT) has been used for site investigation with good results for estimating foundation settlement. Few studies have been conducted to evaluate its applicability in unusual soils, such as the collapsible ones. This work evaluated the use of DMT to predict the stress-strain curve of shallow foundations and its use to identify collapsible soils. The study was carried out for the soil of the Experimental Research Site of Unesp - Bauru, where there is a porous and collapsible clayey fine sand. A device coupled to the DMT was used to flood the soil in situ and get results in the natural and flooded condition. Predictions of the stress-strain curves, as well as the settlement values for the working load were compared to plate load test results in these two conditions. Two criteria for identifying collapsible soils were applied and adaptations were suggested for their use with DMT test data. The DMT coupled device and the proposed procedure to get data at the natural and flooded in situ condition is a promising approach to evaluate the effect of suction on in situ soil behavior. It also has the potential to be used to identify the presence of collapsible soils in a qualitative and preliminary site investigation program.
The vertical deformations of a soil due to typical loads, as in shallow foundations, can influence the performance of buildings. They can cause great damage when not properly predict, particularly in collapsible soils. The study of collapse has been carried out in laboratory, with confined compression tests on undisturbed samples with and without flooding. The Flat Dilatometer (DMT) has been used for site investigation with good results for estimating foundation settlement. Few studies have been conducted to evaluate its applicability in unusual soils, such as the collapsible ones. This work evaluated the use of DMT to predict the stress-strain curve of shallow foundations and its use to identify collapsible soils. The study was carried out for the soil of the Experimental Research Site of Unesp - Bauru, where there is a porous and collapsible clayey fine sand. A device coupled to the DMT was used to flood the soil in situ and get results in the natural and flooded condition. Predictions of the stress-strain curves, as well as the settlement values for the working load were compared to plate load test results in these two conditions. Two criteria for identifying collapsible soils were applied and adaptations were suggested for their use with DMT test data. The DMT coupled device and the proposed procedure to get data at the natural and flooded in situ condition is a promising approach to evaluate the effect of suction on in situ soil behavior. It also has the potential to be used to identify the presence of collapsible soils in a qualitative and preliminary site investigation program.
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Palavras-chave
Investigação do subsolo, Ensaio de campo, Dilatômetro plano, Dispositivo de inundação, Critérios de colapsibilidade, Site investigation, In situ test, Flat dilatometer, Flooding device, Collapsibility criteria