Caracterização geológica da área urbana de Caxias do Sul para fins geotécnicos

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Amostrador para coleta de solos moles

Universidade Federal do Rio Grande do SulEngenhariaDepositad

Identificação e análise de áreas suscetíveis a fluxos de detritos na bacia hidrográfica do Rio Taquari-Antas, RS

O objetivo deste trabalho foi identiicar e analisar as áreas suscetíveis a luxos de detritos na bacia do Rio Taquari-Antas, RS. O mapeamento das áreas suscetíveis foi realizado por meio de uma modelagem espacial com abordagem probabilística, envolvendo a análise morfométrica em locais com ocorrência de luxos de detritos. Os locais foram inventariados por meio de imagens orbitais e expedições em campo, tendo sido mapeadas 193 cicatrizes. A maior parte das cicatrizes se refere ao evento ocorrido em janeiro de 2010, na sub-bacia do rio Forqueta. A partir de alguns testes, foram deinidos três atributos morfométricos para a modelagem: (i) declividades iltradas pela média em janela 5x5; (ii) desnível altimétrico das rampas; (iii) desnível altimétrico dos morros. Estes atributos apresentaram uma tendência central bem deinida, com baixa dispersão dos dados e uma baixa correlação entre si. As cicatrizes mapeadas de deslizamentos apresentam uma área total de 27,3 ha, a maioria delas com comprimento superior a 150 m e largura na ordem de 10 m. O desnível altimétrico médio dos morros com ocorrência de movimentos de massa foi de 317 m, com declividade média de 39%. Os resultados indicam que as áreas suscetíveis a luxos de detritos, 8.147 km² (30% da bacia), estão localizadas principalmente ao longo das linhas de escarpa erosiva, no contato entre a Serra Geral e as unidades geomorfológicas adjacentes. As linhas de escarpa erosiva estão localizadas nas vertentes dos vales dos rios das Antas, da Prata, São Marcos, Carreiro, Guaporé, Forqueta, Fão e Taquari. Em termos absolutos, os municípios com maior área suscetível são Bom Jesus, Jaquirana e Fontoura Xavier. Cerca de 40 municípios apresentam mais de 50% de suas áreas como suscetíveis a luxos de detritos

Experimental properties of bonded soils

The properties of weakly bonded soil have been studied experimentally, mainly by an extension of recent work on artificial bonded sand. Higher stresses were used to fully examine yield of this soil when at denser states. Triaxial equipment applying confining pressures of 3.5 MPa and a belt for measuring radial strain on triaxial soil samples were developed. The influence of saturation procedures on test results was investigated. A new loading arrangement has been used and comparative studies carried out to evaluate its influence. The new arrangement improves the stress distribution in the sample and the quality of the conventional strain measurements taken platen to platen. It also reduces premature failure of tbe sample due to non-uniform stresses. Two natural materiais with some degree of cementation were also tested: the Corinth marl (a soft carbonaceous rock from Greece) and the Chemususu Dam soil (a red lateritic soil from Kenya). Both materiais have similar characteristics to the artificial soil when tested in triaxial compression. The bonded soils have shown a characteristic variation of stiffness with confining pressure. As the pressure is increased the secant initial stiffness increases initially but, at some treshold value of confining stress, show stabilization or even a drop on its absolute value, depending on the initial void ratio and the strength of the bonding. The bonded soils have a curved yield locus which is coincident with the failure envelope at low stresses. The failure envelope in the low stress region is dependent of the stress path, being lower for conventional drained compression tests

Experimental properties of bonded soils.

Imperial Users onl

Contribuição ao estudo do comportamento tensão-deformação-resistência da argila de Sarapuí/RJ

Resumo não disponíve

Experimental properties of bonded soils

The properties of weakly bonded soil have been studied experimentally, mainly by an extension of recent work on artificial bonded sand. Higher stresses were used to fully examine yield of this soil when at denser states. Triaxial equipment applying confining pressures of 3.5 MPa and a belt for measuring radial strain on triaxial soil samples were developed. The influence of saturation procedures on test results was investigated. A new loading arrangement has been used and comparative studies carried out to evaluate its influence. The new arrangement improves the stress distribution in the sample and the quality of the conventional strain measurements taken platen to platen. It also reduces premature failure of tbe sample due to non-uniform stresses. Two natural materiais with some degree of cementation were also tested: the Corinth marl (a soft carbonaceous rock from Greece) and the Chemususu Dam soil (a red lateritic soil from Kenya). Both materiais have similar characteristics to the artificial soil when tested in triaxial compression. The bonded soils have shown a characteristic variation of stiffness with confining pressure. As the pressure is increased the secant initial stiffness increases initially but, at some treshold value of confining stress, show stabilization or even a drop on its absolute value, depending on the initial void ratio and the strength of the bonding. The bonded soils have a curved yield locus which is coincident with the failure envelope at low stresses. The failure envelope in the low stress region is dependent of the stress path, being lower for conventional drained compression tests

Identificação de solos residuais em áreas de risco de Porto Alegre

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Identificação de solos residuais em áreas de risco de Porto Alegre

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