Eder Daniel Teixeira

Analysis of the longitudinal distribution of pressures near the ends of the vertical and horizontal faces in stepped spillway of slope 1V: 0.75H

Stepped spillways have been widely used for flood runoff due to of their constructive advantages and in regards to energy dissipation during the drop, allowing downstream dissipation structures to be designed in smaller dimensions. Due to the need for further studies on the effect of runoff in the chute of the stepped spillway and the analysis of dimensionless numbers used to characterize the longitudinal distribution of the pressures acting on the faces of the steps of a spillway, this study aims to characterize the acting forces on the steps of said spillways. Analyses were performed on a physical model of spillway with a slope of 1V: 0.75H and steps with a height of 6 centimeters. The pressure fields on the steps were analyzed and compared with results found in literature. As a general finding concerning the pressure in the horizontal faces, it was ascertained that the traction and the compression loads have relatively similar magnitudes, the negative pressures being more intense. Regarding the maximum pressures at the horizontal faces of the steps, it should be emphasized that the maximum values of compression have occurred at the end of the chute and that the lower discharges yielded higher values of pressure coefficients.

Longitudinal distribution of extreme pressures in a hydraulic jump downstream of a stepped spillway

The overflow system of a dam safely controls the water level of a reservoir. The design of these structures should predict the damage caused by the action of the turbulent flow to which they are subject to. The combination formed by a stepped spillway followed by a stilling basin promotes a considerable portion of the energy dissipation in the actual chute of the stepped spillway but it is not sufficient to completely avoid the risk of damaging the basin. In this paper, we analyze the longitudinal distribution of extreme pressures in a stilling basin downstream of a stepped spillway. The study was based on the instant pressure data from the tests carried out in a physical model in the Laboratório de Obras Hidráulicas in IPH/UFRGS. Thus, it was found that the pressure behavior is similar to that observed in studies involving smooth chute spillways, except in the area surrounding the base of the stepped spillway, where high pressure fluctuations may occur. This happens as a result of the impact caused by the flow in the dissipation structure, which is not observed downstream of smooth chute spillways due to the existence of a vertical concordance curve between the spillway and the stilling basin.

Macro-turbulent characteristcs of pressures in hydraulic jump formed downstream of a stepped spillway

A bacia de dissipacao tem como finalidade dissipar, atraves de ressalto hidraulico, a energia do escoamento junto a base do vertedouro. Por ser um fenomeno turbulento que provoca amplas flutuacoes de pressao junto ao fundo da bacia, o ressalto hidraulico pode comprometer a estrutura do dissipador por mecanismos como fadiga, subpressao e cavitacao. A utilizacao de vertedouros em degraus permite a dissipacao de uma parte da energia ainda durante o escoamento da agua pela calha, o que possibilita a reducao das dimensoes e do custo da estrutura da bacia de dissipacao. O presente artigo apresenta a analise das distribuicoes longitudinais da pressao media, das flutuacoes de pressao e dos coeficientes de assimetria e curtose, oriundas de ensaios realizados em modelos fisicos hidraulicos. Foi feita uma comparacao das caracteristicas das pressoes obtidas em uma bacia de dissipacao a jusante de um vertedouro em degraus (para numeros de Froude entre 5 e 8) com dados observados em uma bacia de dissipacao a jusante de um vertedouro de calha lisa, com raio de concordância entre a calha e a bacia (para numeros de Froude compreendidos entre 4,5 e 10). A partir dessa analise pode-se concluir que, diferentemente do ocorrido na bacia de dissipacao com calha lisa, as pressoes medias e flutuacoes de pressao observadas na bacia de dissipacao a jusante de calha em degraus tem seu maximo no ponto mais proximo ao pe do vertedouro. O desenvolvimento longitudinal dos coeficientes de assimetria e curtose possibilitaram determinar as posicoes de inicio do descolamento do escoamento, de fim do rolo e de fim da influencia do ressalto hidraulico no escoamento.

Surface drainage system for dry docks in shipyards - Case study of Estaleiro Rio Grande (Technical Note)

This study aims to present a methodology for the design of a surface drainage system for dry docks in shipyards, taking into account the rainfall intensity at the site, the damping capacity of the hydraulic structures (drainage channels) and the pumping capacity of the pumping system. A case study of a dry dock owned by Estaleiro Rio Grande, located at the state of Rio Grande do Sul, is presented. The results obtained indicate alternatives for channel and submersible pump sizing. These pumps would be used to control the dry dock flooding after an intense rainfall event.

Reduced hydraulic model of Forquilha IV tailings dam

This paper presents the development of a reduced hydraulic model (RHM) for the outflow operating system at the Forquilha IV (scale 1:10) tailings dam, owned by Vale S.A. The studies were performed by Centro de Pesquisas Hidraulicas e Recursos Hidricos (CPH) of Universidade Federal de Minas Gerais (UFMG) and the company Vogbr Recursos Hidricos & Geotecnia Ltda. We present here a brief description of the model construction and the test battery set for the structure’s hydraulic analysis. RHM involves the hillside culvert, the dissipation box and the exit to the restitution tunnel. The RHM project represents an essential step in the first analysis of the hydraulic behavior of the prototype, considering the designed flood station (ten thousand-year flood flow), as well as the analysis of its operation with more frequent flows.

Efeito de Escala nos Valores de Pressão Média junto ao Fundo em Bacias de Dissipação por Ressalto Hidráulico Submergido

Hydraulic jumps are widely used as a form of energy dissipation downstream from hydraulic structures. Knowledge regarding average pressure values, pressure fluctuation and extreme values at the bottom of stilling basins is very important for designers seeking a more efficient and economic sizing. This paper aims to present the scale and laboratory effects on the average pressure values from experimental data of three partial reduced physical models (geometric scale of 1:100, 1:50 and 1:32) and from measurements performed at UHE Porto Colombia (owned by Furnas Centrais Eletricas S.A.). Suggestions of minimal scales are presented to be used in reduced models for average pressure evaluation along hydraulic jump stilling basins