Abstract

O presente trabalho versa sobre a possibilidade de redução de custos com a utilização de modais de transportes alternativos ao rodoviário, como o ferroviário e o hidroviário, para a obtenção de areia e brita, agregados para a construção civil de baixo preço, que têm volume de consumo bastante elevado, para sua disponibilização na cidade de São Paulo. As atividades de mineração assim como as demais atividades econômicas na era da globalização têm suas operações bastante semelhantes a níveis de custo, com pouca ou nenhuma possibilidade de redução, sem afetar diretamente a qualidade. O que se busca é identificar alternativas de ganho na competitividade por meio da redução de custos logísticos, única opção para atingir um melhor preço de venda. Para tanto, valeu-se de estudo das características e aplicabilidade das várias formas de transporte, como fator estratégico para a composição de custos adequados à competitividade desejada pelas empresas envolvidas na sua comercialização. Ao mesmo tempo, no emprego dessas alternativas de transporte, encontra-se a possibilidade de redução do congestionamento do tráfego e de melhoria na condição ambiental pela utilização de modais mais limpos. Trata-se de estudo de caso de natureza descritivo-exploratória do tipo quali-quantitativo com coleta de dados por meio de entrevista aberta, de pesquisa documental e bibliográfica. A discussão dos dados, oriundos das fontes primárias e da simulação permitiu chegar ao resultado que viabiliza a utilização do modal ferroviário a curto prazo e a utilização do hidroviário mais a longo prazo pela inexistência de infra-estrutura. O seu emprego resulta, além da redução de custos com frete, na melhoria do tráfego de veículos e na qualidade ambiental. This work aims at focusing the possibility of cost reduction by the utilization of alternative means of transportation in relation to highways, railways and waterways in order to obtain sand and gravel, which are highly consumed, for civil construction at low added value to be available in São Paulo city. The mining activities as well as the other economic activities in the globalization era have very similar operations at cost level, having little or no possibility of reduction without directly affecting quality. What is searched is the identification of gain alternatives in competitiveness by reducing costs in logistics, it being the only option to reach a better sale price, by means of studying characteristics and applicability of various ways of transportation, as a strategic factor to compose adequate costs in relation to the competitiveness desired by the companies involved in their commerce. Likewise in the application of such alternatives of transportation there is a possibility of reducing traffic jams and improving the environmental condition by using cleaner means. It is a case study of descriptive-exploratory nature of the qualitative-quantitative type with collection of data in open interviews, documental and bibliographical research. The discussion of data coming from primary sources and from simulation made possible the result that makes viable the utilization of railway means in the short run and the utilization of waterway in the long run due to lack of infrastructure. Besides cost reduction in freight, its application brings improvement to traffic of vehicles and environmental quality.

Abstract

Suction caisson has gained interest in recent years as an alternative foundation for offshore wind turbines due to its cost-effectiveness and easy installation compared to conventional foundations such as monopile. After initial penetration due to its self-weight, suction is applied until the caisson reaches the desired depth. Applying suction provides additional driving force due to the pressure difference between inside and outside the caisson and induces seepage that degrades friction and tip resistance, which further facilitates the installation. The seepage plays a vital role in installing suction caisson in sand; however, it might change the soil state which affects the ultimate bearing capacity of the caisson. Several research works have been conducted to study the suction caisson installation in sand. However, the complexities of the problem including large deformation, solid-fluid and soil-structure interaction, inhibited these studies from fully understanding the installation mechanism. This paper proposes a large deformation modeling framework by using the material point method (MPM). MPM is a hybrid Lagrangian-Eulerian particle-based method that uses material points over a fixed computational mesh where governing equations are solved. During the convection of the particles, the background mesh is kept fixed, making it suitable for large deformation problems. The model considers soil-structure interaction by adopting a Coulomb contact algorithm between the caisson and surrounding soil. In this paper, the stability of the contact algorithm is ensured by correcting material point velocities in the vicinity of the caisson interface using a limiting velocity based on the element size and time step. The framework is validated by comparing a simulation of caisson installation under constant velocity with results published in the literature. Our proposed framework’s results agree with previous published results, demonstrating that the simplified stabilization procedure does not affect the simulation results. This is a promising result that will enable the incorporation of fully coupled analysis to better understand the effects of induced seepage on the installation mechanism of suction caissons.

Abstract

In geotechnical site characterization, Cone Penetration Testing (CPT) is a fundamental method for evaluating subsurface conditions of granular materials such as sands, silts, and non-plastic tailings. This study advances CPT simulations by incorporating the fabric anisotropy variable A into the SANISAND-F model and utilizing the Material Point Method (MPM), with a specific focus on the role of evolving fabric within an anisotropic critical state framework. The objective is to deepen the understanding of how the evolving fabric of soils influences macroscopic site characterization outcomes. Through carefully controlled initial conditions, including void ratio and confining pressure, the study aims to demonstrate the impact of fabric anisotropy on CPT resistance measurements. Assessment of the evolution of material state based on the key constitutive ingredient of the model allows for explaining the reason behind the respective values of cone tip resistance observed from the CPT simulations, considering fabric anisotropy and the anisotropic critical state framework. This approach enhances the modeling of this site characterization method, providing a more comprehensive framework for interpreting soil mechanical behavior and enhancing predictive modeling capabilities

Abstract

In the offshore/marine environment, foundation elements need to be particularly long or wide in diameter in order to reach a competent bearing stratum through weak, low-strength sediments. The seabed conditions in oil&gas and renewable energy projects can be difficult, and the skin friction produced during driving operations could be insufficient to support the service loads placed on the structures. In this study, low-pressure injections of an acrylate gel and a colloidal silica product were made into reference sand, and interface direct shear tests were conducted under constant stiffness conditions. Conventional ground improvement projects already employ these items. Oedometer tests on untreated sand were used to evaluate the stiffness properties of the sand, which provided the foundation for determining the stiffness in the DSTCNS system. At an initial low relative density (Dro) of 0.40, Holcim sand samples were generated. This value is thought to be representative of the top zone of normal sediment profiles under offshore settings. Shearing the sand over a steel plate has been done by direct shear experiments conducted under constant normal stiffness conditions. The effects of injection have been compared using pre- and post-grout interface shear tests. The new binders' activity is causing an increase in skin friction, according to the results.