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Hydraulic structures with water level differences between upstream and downstream are subjected to seepage in foundation soils. Two sources of weakness are to be guarded against: (1) percolation or seepage may cause under-mining, resulting in the collapse of the whole structure, and (2) the floor of the apron may be forced upwards, owing to the upward pressure of water seeping through pervious soil under the structure. Many earlier failures of hydraulic structures have been reported due to these two reasons. The curves and charts prepared by Khosla, Bose, and Taylor still form the basis for the determination of uplift pressure and exit gradient for weir apron founded on pervious soil of infinite depth. However, in actual practice, the pervious medium may be of finite depth owing to the occurrence of a clay seam or hard strata at shallow depths in the river basin. Also, a general case of weir profile may consist of cutoffs, at the two ends of the weir apron. In addition to the cutoffs, pervious aprons are also provided at the downstream end in the form of (i) inverted filter, and (ii) launching apron. These pervious aprons may have a thickness of 2 to 5. In order to accommodate this thickness, the bed adjacent to the downstream side of downstream cutoff has to be excavated. This gives rise to the formation of step at the downstream end. Closed form theoretical solutions for the case of finite depth seepage below weir aprons with end cutoffs, with a step at the downstream side are obtained in this research. The parameters studied are : (i) finite depth of pervious medium, (ii) two cut offs at the ends, and (iii) a step at the downstream end. iv The resulting implicit equations, containing elliptic integrals of first and third kind, have been used to obtain various seepage characteristics. The results have been compared with existing solutions for some known boundary conditions. Design curves for uplift pressure at key points, exit gradient factor and seepage discharge factor have been presented in terms of nondimensional floor profile ratios. Publications resulting from the dissertation are: 1. Jain, Arun K. and Reddi, L. N. “Finite depth seepage below flat aprons with equal end cutoffs.” (Submitted to Journal of Hydraulic Engineering, ASCE, and reviewed). 2. Jain, Arun K. and Reddi, L. N. “Seepage below flat apron with end cutoffs founded on pervious medium of finite depth.” (Submitted to Journal of Irrigation & Drainage Engineering, ASCE). 3. Jain, Arun K. and Reddi, L. N. “Closed form theoretical solution for finite depth seepage below flat apron with equal end cutoffs and a downstream step.” (Submitted to Journal of Hydrologic Engineering, ASCE). 4. Jain, Arun K. and Reddi, L. N. “Closed form theoretical solution for finite depth seepage below flat apron with end cutoffs and a downstream step.” (Submitted to Journal of Engineering Mechanics, ASCE).

A dimensionless equation is developed which describes the flow profile in rectangular channels with spatially varied flow. This equation is solved for various slopes and rates of discharge. The results show that when the slope and roughness are constant the dimensionless profiles are also constant over a very wide range of discharge. Once the dimensionless profile is established the water surface curve may be rapidly and accurately determined. Tests were conducted in the laboratory which reasonably verified the validity of the dimensionless profiles. / Master of Science

Call number: LD2668 .T4 1986 V57 / Master of Science / Biological and Agricultural Engineering

O presente trabalho apresenta soluções e análises desenvolvidas em estruturas extravasoras em aproveitamentos a fio dágua, envolvendo análises nos critérios de operação de diversos tipos de descarregadores, tais como: soleira normal, labirinto, tulipa e comportas específicas. Para tanto se faz necessário o estudo e comparação de resultados a serem desenvolvidos em cada projeto com relação aos fatores hidráulicos, hidrológicos, geológicos, topográficos e dos riscos envolvendo prejuízos decorrentes de falhas nas estruturas hidráulicas. A avaliação de extravasores labirinto em aproveitamentos hidrelétricos de projetos aprovados pela Agência Nacional de Energia Elétrica ANEEL tem o objetivo de analisar a segurança em relação à construção e à operação, com foco no desenvolvimento de descarregadores adequados para cada estudo de caso presentes neste trabalho. Esta avaliação indica as condições geométricas, econômicas e hidráulicas do extravasor labirinto adequado para cada situação de aproveitamento hidrelétrico a fio dágua. / This paper studies solutions and analysis developed in spillways structures in hydroelectric development trickle, involving analysis of the operation criteria of several types of dischargers, such as threshold normal maze, morning glory and specific gates. For this purpose it is necessary to study and compare the results to be developed in each project about the factors hydraulic, hydrologic, geologic, topographic and risks involving losses due to failures in hydraulic structures. The evaluation of spillways maze in hydroelectric of projects approved by the National Agency of Electric Energy - ANEEL aims to analyze the safety for the construction and operation, focusing on the development of suitable dischargers for each case study in this work. This assessment indicates the geometric, economic and hydraulic conditions of the most suitable spillways maze for each situation of hydroelectric development trickle.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / Includes bibliographical references. / by J. Kim Vandiver. / Ph.D.

Lietuvoje įrengta 1590 tvenkinių, pastatyta daug kitokių hidrotechnikos statinių ir beveik kiekviename iš jų yra gelžbetoninių elementų ar konstrukcijų. Naudojami statiniai patiria įvairių apkrovų ir agresyvios aplinkos poveikį, dėl to jie ilgainiui nusidėvi, formuojasi pažaidos, statiniai genda ir tampa nebetinkami naudoti. Darbo tikslas – įvertinti defektų ir pažaidų įtaką naudojamų hidrotechnikos statinių gelžbetoninių konstrukcijų techninei būklei. 2006 metais tyrinėtos Marijampolės rajono naudojamų hidrotechnikos statinių gelžbetoninės konstrukcijos. Nustatyta pagrindinė konstrukcijų stiprum���� apibūdinanti charakteristika – gniuždomojo betono stipris. Užfiksuoti konstrukcijų defektai bei pažaidos, aptariamos galimos jų atsiradimo priežastys, konstrukcijų būklė įvertinta balais. Nurodyti dažniausiai pasitaikantys konstrukcijų defektai bei pažaidos, kurie atsirado dėl netinkamų sudėčių bei savybių betono, naudojimo trūkum��. / There are approximately 1590 dams and many other hydraulic structures constructed in Lithuania. Most of them have reinforced concrete elements or constructions. Due to different loads and environmental impact, condition of operational structures gets worse in time. Therefore, some deterioration may occur which leads structures to failure and makes them no longer useful for exploitation. The purpose of this work is to evaluate the influence of defects and deteriorations to the technical state of reinforced concrete hydraulic structures. In 2006, reinforced concrete constructions of hydraulic structures were investigated in Marijampole district. Compression strength is determined as the main characteristic of these constructions. Defects and deteriorations of constructions are noticed; main reasons that influence deterioration are discussed; and condition of constructions is estimated by points. It is established that most common defects and deteriorations are caused because of the use of unfit manufactured concrete and its shortage.

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