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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modelo neuronal para previsão de recalques em estacas hélice contínua, metálica e escavada / Neuronal model for prediction of settlements in cintinua auger piles, metal and excavated

Silveira, Mariana Vela 01 August 2014 (has links)
SILVEIRA, M. V. Modelo neuronal para previsão de recalques em estacas hélice contínua, metálica e escavada. 2014. 148 f. Dissertação (Mestrado em Engenharia Civil: Geotecnia) – Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2014. / Submitted by Marlene Sousa (mmarlene@ufc.br) on 2015-04-09T12:13:49Z No. of bitstreams: 1 2014_dis_mvsilveira.pdf: 2442039 bytes, checksum: ff2533d468edafc815c81f1d3cfcc253 (MD5) / Approved for entry into archive by Marlene Sousa(mmarlene@ufc.br) on 2015-04-16T11:57:17Z (GMT) No. of bitstreams: 1 2014_dis_mvsilveira.pdf: 2442039 bytes, checksum: ff2533d468edafc815c81f1d3cfcc253 (MD5) / Made available in DSpace on 2015-04-16T11:57:17Z (GMT). No. of bitstreams: 1 2014_dis_mvsilveira.pdf: 2442039 bytes, checksum: ff2533d468edafc815c81f1d3cfcc253 (MD5) Previous issue date: 2014-08-01 / Predicting the settlement in deep foundation is a very complex, uncertain and not yet fully understood, due to the many uncertainties associated with factors that affect the magnitude of this deformation. Artificial Neural Network (ANN) is a tool that works similarly to the human brain, its main unit, the artificial neuron, works in a similar way to the biological neuron. This alternative tool has been successfully applied in many geotechnical engineering problems and can therefore be used as an alternative tool to evaluate the behavior of settlement in isolated piles. In this paper, the ANN used were the multilayer perceptron type, employing a supervised training that uses the error back propagation algorithm. The model developed relates settlement in isolated piles with the type and the geometrical properties of the piles (diameter and length), the stratigraphy and characteristics of compactness or consistency of soils by means of the SPT tests results, and the load applied, obtained in static pile load tests performed in continuous helix, steel driven and excavated pile types. The data set used to model consisted of 1.947 samples of input and output. QNET 2000 was the program used to assist the training and validation of various architectures of neural networks. The architecture formed by 10 nodes in the input layer, 28 neurons distributed in 4 intermediate layers and one neuron in the output layer, corresponding to the measured discharge for cutting (A10: 14:8:4:2:1) was the one that showed the best performance, with the correlation coefficient between the estimated settlements and settlements measured during the validation phase of 0.94, such value can be considered satisfactory when considering the prediction of a complex phenomenon. After comparing the performance of the applied load x settlement estimated by model proposed curve with the applied load x settlement measured in static pile load test curve and the applied load x settlement estimated by an elasto-plastic model thru numerical simulation, it was found that the ANN were able to understand the behavior of deep foundations of continuous helix, steel driven and excavated piles type, allowing among other things, the definition of workloads and load limits at the pile. / Estimar o recalque em estacas é um problema muito complexo, incerto e ainda não totalmente compreendido, devido às muitas incertezas associadas aos fatores que afetam a magnitude desta deformação. As RNA são ferramentas que funcionam analogamente ao cérebro humano, e sua unidade principal, o neurônio artificial, trabalha de maneira semelhante ao neurônio biológico. Esta ferramenta alternativa vem sendo aplicada com sucesso em muitos problemas de engenharia geotécnica, podendo, portanto ser utilizadas como uma ferramentas alternativas para avaliar recalques em estacas isoladas. Nessa pesquisa as RNA utilizadas foram do tipo perceptron de múltiplas camadas, empregando um treinamento supervisionado utilizando o algoritmo de retropropagação do erro. O modelo desenvolvido relaciona o recalque em estacas isoladas com as propriedades geométricas das estacas (diâmetro e comprimento), a estratigrafia e as características de compacidade, ou consistência dos solos por meio dos resultados obtidos nos ensaios SPT, e a carga atuante, obtidas em provas de carga realizadas em estacas hélice contínua, cravada metálica e escavada. O conjunto de aprendizagem foi composto por 1947 exemplos de entrada e saída. Com auxilio do programa QNET2000 foram treinadas e validadas várias arquiteturas de redes neurais. Após comparar o desempenho da curva carga x recalque elaborada com os recalques estimados pelo modelo proposto com a curva carga x recalque resultante da prova de carga estática e com a curva carga x recalque gerada pelo emprego do programa comercial baseado em elementos finitos tridimensionais PLAXIS 3D Foundation, constatou-se que as RNA foram capazes de entender o comportamento das fundações profundas do tipo estacas hélice contínua, escavada e cravada metálica, possibilitando dentre outras coisas, a definição das cargas de trabalho e cargas limites nas estacas.

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