Calibration of rock cutting numerical model based on monitoring data

Prediction of the deformation increment and the final displacement of the rock cutting is a challenging task. Many ambiguities linked with unpredictable nature or rock mass make it difficult to apply the adequate contingency measures. Implementation of common approach, which includes modelling of discontinuity effects with estimated reduction of rock mass strength and modulus of elasticity, usually does not yield satisfactory results. Therefore, a calibration of FEM based numerical model was made by conducting parametric analysis which feeds upon data obtained from extensive on-site monitoring system. A step forward was made in description of numerical parameters of karst discontinuities through consideration of monitoring results, as well as excavation procedures, position, inclination and length of discontinuities and PDC (project design change)

Análise da soldabilidade do aço 22MnB5 no processo de solda ponto por resistência.

Submitted by repositorio repositorio ([email protected]) on 2016-08-29T12:45:04Z No. of bitstreams: 1 dissertacao_bacic_junior_2016.pdf: 7062771 bytes, checksum: cf312d7d383f94cc04a231d61693170c (MD5)Made available in DSpace on 2016-08-29T12:45:04Z (GMT). No. of bitstreams: 1 dissertacao_bacic_junior_2016.pdf: 7062771 bytes, checksum: cf312d7d383f94cc04a231d61693170c (MD5) Previous issue date: 2016-03O aço que motivou este trabalho é o 22MnB5 que é o mais utilizado pela industria automotiva nos processos de estampagem a quente. Este aço se diferencia de outros pela composição química e microestrutura, sendo que, antes do inicio da soldagem, a microestrutura do 22MnB5 é predominante martensitica devido ao tratamento térmico de têmpera que lhe garante elevado nível de resistência à tração. O objetivo deste trabalho foi analisar a união de juntas de aço 22MnB5 pelo processo de solda a ponto por resistência elétrica. Numa primeira etapa procurou-se determinar os níveis dos parâmetros secundários e a força de compressão dos eletrodos que seriam usados nos ensaios. Depois, o comportamento da soldagem foi estudado utilizando-se um planejamento experimental com 4 níveis de tempo de soldagem e 6 níveis de corrente de solda, tendo como respostas o diâmetro dos pontos de solda, a força de resistência à tração no cisalhamento e o tipo de fratura, além de ensaios de microdureza, MEV e metalografia. O parâmetro que mais influenciou na formação do ponto de solda foi a corrente elétrica, onde um aumento em seu nível causou numa proporção direta e até certo limite, um aumento no diâmetro do ponto e na força de resistência ao cisalhamento. A melhor condição de soldagem ocorreu quando a corrente de solda foi aplicada com nível de intensidade de 5,1 kA (85% do nível máximo do equipamento) durante 8 ciclos, com uma pressão de 5 bar e rampa de subida de corrente de 20 ciclos. Nesta condição, a força máxima atingiu seu pico máximo de 16,2 kN para um ponto com diâmetro de 5,5 mm, obtidos sem expulsão de material. Foi observado que níveis maiores de corrente com tempos menores de soldagem obtiveram melhores resultados nos ensaios de tração

oVERFLOw project

This deliverable is a report on the development of a strategy for adaptation measures to flood events for the embankments, riverbanks and bridges, which can afterwards be used for the case study areas considered in the Overflow project. The deliverable presents a comprehensive approach that enables the choice of the best adaptation measures to overcome the vulnerability of critical infrastructure to flooding events. The most suitable countermeasures can therefore be selected based on the outcomes of the vulnerability assessment and risk forecasting tool. Such a strategy will be essential for the relevant authorities and IMs. The strategy proposes optimal adaptation measures depending on areas specificities, incorporating socio-economic and environmental multi-objective optimization

Application of neural networks for the reliability design of a tunnel in karst rock mass

This paper offers a solution to overcome time-consuming numerical analysis for the evaluation of the impact of tunnel construction in a complex karst environment by implementing Monte Carlo Simulation (MCS) using a neural network (NN) tool. The rock mass is described using three parameters: Geological Strength Index, the uniaxial compression strength of the intact rock, and the Hoek–Brown parameter for the intact rock mi . By using their probabilistic distribution as an input, a developed neural network NetTUNN produces probabilistic distributions of tunnel crown displacement, rock bolt axial load, and shotcrete uniaxial compression stress. A full MCS is then applied on these NetTUNN outputs to determine the reliability index and probability of failure for the relevant limit states. To demonstrate the potential of NN in tunnel design, a case study of Tunnel Pecine in Croatia is used, where the NetTUNN-assisted MCS assessment served as a benchmark to evaluate approximate reliability assessment techniques. It was shown that the developed NN can be used as an accurate surrogate model for determination of probabilistic distributions of tunnel design parameters. Further, it was shown that approximate reliability assessment techniques generally overestimate the reliability index and underestimate the probability of failure when compared to the NetTUNN-assisted MCS.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin

Categorization of the condition of railway embankments using a multi-attribute utility theory

In the current economic climate, it is crucial to optimize the use of all resources regarding railway infrastructure maintenance. In this paper, a multi-attribute decision support framework is applied to categorize railway embankments in order to prioritize maintenance activities. The paper describes a methodology to first determine the current condition of embankments using a combination of ground penetrating radar (GPR) surveys, visual inspection, and historical data about maintenance activities. These attributes are then used for the development of a multi-attribute utility theory model, which can be used as a support for decision making process for maintenance planning. The methodology is demonstrated for the categorization of 181 km of railway embankments in Croatia.Geo-engineerin

Desarrollo emprendedor: América Latina y la experiencia internacional

Esta publicación analiza el perfil de los emprendedores y la forma en que ellos crean negocios de alto crecimiento en trece países de América Latina, el este de Asia y el sur de Europa. Asimismo, ofrece un conjunto de estudios de caso sobre políticas y programas de desarrollo emprendedor en América y en Europa. El análisis comparativo de los trece sistemas de desarrollo emprendedor, en combinación con los estudios de caso, permite identificar un conjunto de áreas y recomendaciones a partir de las cuales los gobiernos y las agencias de desarrollo de América Latina y el Caribe pueden actuar a fin de promover la creación de empresas e impulsar el desarrollo del sector privado.