Abstract Terzaghi (1943) developed an empirical method for primary consolidation due to a load applied at constant rate (ramp load) until the end of construction at time tc. The method considers that the settlement at a time t during construction, can be evaluated admitting the load applied instantaneously at time t/2. In this research, two alternative modifications are proposed for this Terzaghi’s empirical recommendation. The first one is based on a variable fraction of time t and the second modification keeps Terzaghi’s suggestion (t/2) but makes reductions in the average degree of consolidation Uv. Computed results for different construction time factors Tv were compared to Olson (1977) analytical solution. The first approach yielded a maximum difference of approximately 2.40% while the second alternative gave results that are practically the same as those calculated by Olson’s solution. The validity of these new approaches was also proven by reproducing odometer test results with good agreement.

Abstract The breakwater failure at the Sergipe Harbor is a well-known event among the Brazilian geotechnical community, which provided great knowledge about the behavior of embankments on soft soils, although some questions still remain, since the back analysis diverged from the field outcome. In this context, this work aims to carry out a numerical analysis of the construction of the breakwater using the finite element method to understand the mechanisms of failure. A fully coupled flow-deformation analysis was performed in Plaxis 2D software, using the Soft Soil Creep and Mohr-Coulomb constitutive soil models. The Volume Method was also applied to estimate the stability of the slopes, from the calculated numerical displacements. The interpretation of the results allowed to verify that the analysis simulated behaviors that had been raised as responsible for the failure. High excess pore pressure levels were generated in the phase at which failure occurred, in addition to a strain softening behavior, which, alongside the progressive failure, could justify why the back analysis considering unrealistic gains in undrained strength, calculated by the increase of the vertical effective stresses, had provided missed factors of safety. Although shear deformations and horizontal displacements were verified for both sides of the breakwater, the “shared failure” assumption could not be verified, since the shear stress was mobilized in the rockfill. wellknown well known community soils remain outcome context flowdeformation flow deformation D software MohrCoulomb Mohr Coulomb models slopes occurred strength stresses safety shared rockfill

Abstract In engineering practice, loading varies with time. However, the classical one-dimensional theory of consolidation assumes the stress increase is instantaneously applied. Many approaches to the problem of time-dependent loading have been proposed over the years, from approximate methods to full developments of differential equations. The paper presents a simple method for finding a closed-form consolidation solution for time-dependent loading without the need for differential equations. Two sets of general equations were derived for both excess pore pressure and average degree of consolidation. Equations were solved for linear, parabolic, sinusoidal, and exponential load functions. Stepped and cyclic loads were also addressed and a numerical solution was developed to verify the obtained result. The method proved to be easy to apply and provides solutions with great simplicity. A case study of non-instantaneous loading on soft clay was also analyzed, and settlement prediction showed good results when compared to readings of the settlement plates. practice time However onedimensional one dimensional applied timedependent dependent years closedform closed form linear parabolic sinusoidal functions result simplicity noninstantaneous non instantaneous analyzed plates

RESUMO O objetivo deste artigo foi avaliar a eficiência de modelos de primeira ordem para previsão da geração de biogás em aterros sanitários, comparando resultados previstos com aqueles disponíveis em relatórios de monitoramento de captação ao longo de anos de operação. Os aterros sanitários estudados neste trabalho operam no âmbito de projetos de Mecanismo de Desenvolvimento Limpo (MDL), que podem receber incentivos financeiros - certificados de redução de emissões ou créditos de carbono. Foram selecionados quatro aterros sanitários brasileiros (Nova Iguaçu, Paulínia, Caieiras e Bandeirantes) que dispunham das quantidades anuais de resíduos sólidos efetivamente depositadas durante o primeiro período de crédito de sete anos, eliminando assim uma importante fonte de incertezas do modelo de previsão. Limitações dos modelos recomendados pelas diretrizes do Intergovernmental Panel on Climate Change (IPCC) são discutidas, incluindo erros intrínsecos na formulação matemática e de má interpretação no tempo para início da geração do biogás. É também proposta uma modificação na ferramenta de projeto CDM Tool atualmente utilizada em projetos MDL de emissão de biogás em depósitos de resíduos sólidos.

ABSTRACT The objective of this study was to evaluate the efficiency of first-order models for prediction of biogas emission in landfills, comparing forecasts with observations registered along the years of landfill operation. The landfills analyzed in this research operate within Clean Development Mechanism (CDM) that may receive financial incentives - certified emission reductions or carbon credits. Four Brazilian landfills (Nova Iguaçu, Paulinia, Caieiras and Bandeirantes) have been selected, for which the annual quantities of waste actually deposited during the first seven-year period of carbon credits were available, thus eliminating a major source of uncertainty in the forecasting models. Limitations of the models of the first order recommended by the guidelines of the Intergovernmental Panel on Climate Change (IPCC) are discussed, including intrinsic errors in the mathematical formulation and misinterpretation of the starting time for prediction of biogas emission. It is also proposed a modification in the CDM Tool model, currently used for biogas emission in solid waste deposits operating as CDM projects.

RESUMO O presente trabalho apresenta resultados preliminares de um inventário de emissões de gases de efeito estufa (GEE) elaborado para o campus da PUC-Rio, situado no bairro da Gávea, zona sul da cidade do Rio de Janeiro. Foram identificadas emissões de GEE nos escopos 1 (combustão estacionária e móvel, emissões fugitivas), escopo 2 (consumo de energia elétrica) e escopo 3 (transporte, viagens, geração e descarte de resíduos sólidos), seguindo metodologias recomendadas pelo Programa Brasileiro GHG Protocol. Dentre as fontes de emissão, a mais difícil de quantificar foi justamente a principal geradora, relacionada com os deslocamentos entre o campus e as residências dos 20 mil potenciais frequentadores diários da PUC-Rio durante 2011.

ABSTRACT This paper presents the preliminary results of a greenhouse gas (GHG) inventory prepared for the campus of PUC-Rio, located in the district of Gávea, south zone of the city of Rio de Janeiro. GHG emissions have been identified in scope 1 (stationary and mobile combustion, fugitive emissions), scope 2 (electricity consumption) and scope 3 (transport, travel, generation and disposal of solid waste), according to the methodologies recommended by the Brazilian GHG Protocol Program. Among the sources of emissions, the main generator was the most difficult to quantify, and it was related to the commuting between the campus and the residences of estimated 20,000 people who frequented PUC-Rio daily in 2011.

Neste trabalho são discutidos os principais aspectos relacionados à geração de resíduos da construção civil, sob ponto de vista de sustentabilidade das edificações. Esse conceito exige, das novas construções, a adoção de projetos criativos e eficientes, com soluções adequadas para as diversas fases de vida da obra, incluindo a previsão do reaproveitamento e descarte de materiais ao fim de sua vida útil. Um dos problemas atuais da gestão de resíduos da construção civil é que a segregação dos materiais por classe, visando à sua posterior reciclagem ou descarte, só acontece na cidade do Rio de Janeiro em grandes obras com canteiros instalados, embora mais da metade da quantidade produzida seja proveniente de pequenas obras com resíduos descartados em caçambas de rua ou simplesmente lançados em vias públicas ou terrenos baldios. É sugerido um plano de gestão circular, especialmente voltado para os pequenos geradores, com obrigatoriedade de segregação dos materiais, instalação de pontos de recolhimento pelos bairros da cidade e implantação de centros de tratamento de resíduos da construção civil, operados por associações de catadores, com objetivo de produção de materiais reciclados. O sucesso da proposta depende da efetiva participação de todos os agentes envolvidos no processo, como o poder público, proprietários, empresas e demais profissionais da indústria da construção civil.

In this paper the major issues related to the generation of construction waste are discussed from the point of view of sustainability of buildings. This concept requires the adoption for new constructions of creative and efficient projects, with appropriate solutions to the various cycles of life, including the provision for recycling and disposal of materials at the end of the useful life of the building. One of the problems concerning the management of civil construction waste is that segregation of materials by class, aiming at their subsequent recycling or disposal, only happens in the city of Rio de Janeiro within large projects with installed construction sites, although more than half of the produced amount of waste comes from small works which discard their waste into street dump-carts or simply thrown it away on public roads or wastelands. A circular management plan is herein suggested, especially geared for small waste generators, including mandatory segregation of all materials, installation of public collection points through the city neighborhoods and implementation of treatment centers of construction waste, operated by associations of waste collectors, aiming the production of recycled materials. The success of this proposal depends on the effective participation of all agents involved in the process, as the government, owners, companies and other professionals in the construction industry.