Abstract As the consideration of soil-structure interaction is increasingly being incorporated into design practice, there is a need for solutions that consider the most relevant aspects of the behaviour of both the concrete and the soil, some of which are time-dependent. The present work introduces a model that suits both the structure and the foundation – including the supporting soil – allowing the coupled analysis of hardening on cure, creep, shrinkage and cracking of concrete, and consolidation of soil. Both the structure and the foundation are modeled as one-dimensional finite elements. The time-dependent behaviour of the concrete and soil is modeled using Kelvin chains. For the structural elements, a mixed finite element formulation is used. Validation tests were conducted in the proposed modeling, comparing its results with available experimental and analytical data. The study of a reinforced concrete continuous beam supported by foundations on consolidating clay considering the time-dependent behaviour of the materials showed considerable changes in the effects of the soil-structure interaction.

RESUMO O projeto e a gestão inadequados da camada de cobertura de um aterro sanitário produzem impactos ambientais prejudiciais ao meio ambiente. Uma alternativa disponível é desenvolver cenários baseados na simulação de modelos físicos e computacionais para representar o balanço hídrico que se espera que ocorra em uma camada de cobertura do aterro por meio de um experimento de campo. O presente trabalho investiga o projeto de cobertura final de um aterro sanitário no município de Seropédica, localizado no estado do Rio de Janeiro - Brasil. Mais especificamente, a cobertura compacta do solo, que é amplamente utilizada para a cobertura final de aterro de resíduos sólidos urbanos, é avaliada em contraste com a cobertura vegetal por gramíneas, cobertura vegetal por braquiária e barreira capilar. Para realização dessa tarefa, forçantes hidrometeorológicas, nomeadamente precipitação e temperatura na escala diária, foram obtidas da estação meteorológica de Anchieta, situada nas proximidades da área de estudo. Os códigos computacionais Hydrus 1D e 2/3 D foram empregados para desenvolver um conjunto de cenários para acompanhar a evolução da pluma de contaminação no interior do aterro ao longo do período de 20 anos com algum grau de confiabilidade. Ressalta-se que a avaliação realizada indica a possibilidade de controlar a liberação de chorume e, consequentemente, de evitar a contaminação do meio ambiente, notadamente para prevenir a poluição do solo e dos recursos hídricos. A cobertura vegetal por gramíneas e braquiárias apresentou importantes mecanismos de controle com relação ao movimento da pluma contaminante. Além disso, deve-se notar que os melhores resultados para a cobertura final do aterro foram alcançados para a barreira capilar, enquanto que os resultados de baixo desempenho foram obtidos para o solo compacto comumente empregado.

ABSTRACT Improper design and management of the cover layer of a sanitary landfill has been proven to produce harmful environmental impacts on the environment. One alternative at hand is to develop scenarios based on simulation of physical and computational models to represent the expected field water balance of a landfill coverage layer. This paper investigates the design of a sanitary landfill final cover in the municipality of Seropédica, which is located at the state of Rio de Janeiro - Brazil. More specifically, the compact soil coverage, which is widely used for landfill final cover of municipal solid waste, is evaluated in contrast to vegetation cover by grass, vegetation cover by brachiaria and capillary barrier. To accomplish such task, hydrometeorological forcing conditions, namely daily rainfall and temperature, were retrieved from the Anchieta weather station, which is situated nearby the study area. The Hydrus 1D and 2/3 D computational codes were employed to develop a set of scenarios to follow the contamination plume evolution within the landfill along the time frame of 20 years with some degree of reliability. It should be noted that the performed evaluation indicates the possibility to control the leachate release and consequently to avoid contaminating the environment, notably to prevent soil and water resources pollution. Vegetation cover by grass and brachiaria showed important control mechanisms with respect to the movement of the contaminant plume. In addition, it should be noticed that the best results for the landfill final cover were achieved for the capillary barrier, while poor performance results were obtained for the commonly employed compact soil.

This paper describes a novel Boundary Element Technique developed for application to one-dimensional and a class of two-dimensional diffusive-advective potential problems. It is based on transformation of variable procedure to establish an integral equation inverse sentence, dealing only with boundary variables, using a fundamental solution associated with a diffusive problem. To apply the technique described here, the original differential equation is rewritten and flow potential functions are employed to contract terms which appear in the original equation, giving as a result an equivalent equation expressed in terms of the derivative of the product of two functions. This new form of the governing equation, together with the proposed transformation of variables is quite convenient for the application of the boundary element methodology: a very simple discretization procedure arises; the resulting algorithms require low CPU time and the numerical results are quite accurate.

By coupling the Boundary Element Method (BEM) and the Finite Element Method (FEM) an algorithm that combines the advantages of both numerical processes is developed. The main aim of the work concerns the time domain analysis of general three-dimensional wave propagation problems in elastic media. In addition, mathematical and numerical aspects of the related BE-, FE- and BE/FE-formulations are discussed. The coupling algorithm allows investigations of elastodynamic problems with a BE- and a FE-subdomain. In order to observe the performance of the coupling algorithm two problems are solved and their results compared to other numerical solutions.