As barragens de enrocamento com face de concreto (BEFC) têm sido construídas com freqüência crescente em todo mundo. Apesar disso, os critérios de. Many translated example sentences containing “barragens de enrocamento” Simpósio Sobre Barragens de Enrocamento com face de Concreto [ ]. 15 out. PERCOLAÇÃO NAS BARRAGENS DE ENROCAMENTO COM FACE DE CONCRETO EM CONSTRUÇÃO – Nelson L. de S. Pinto.
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It must be pointed out that this feature is critical on abutments. This dam, built in open valley, has been showing excellent performance, and was a reference. For a more favorable behavior in relation to these efforts, the concrete face should be divided into panels that can reduce or eliminate some of the soliciting efforts above mentioned.
This problem was solved in further dams by changing the zoning of the fill material in the region of interest and new design of the perimetral joint, which had more than one sealing element and, as an additional defense line, when viable, a clay fill on the perimetral joint. Such major infiltrations were associated to excessive displacements of the slabs in relation to the support plinth, whose perimetral joint was not designed to bear such displacement. Also the thickness of the compaction layers should be adjusted, in function of the quality, gradation and shape of materials and of the type of compacting roller used.
Flávio Alberto Crispel
On the other hand, the tensile joints seals of the slabs on the abutments regions should be capable to absorb the largest displacements resulting from the compression of the joints in the central area.
Skip to main content. Such width reduction would also restrict the area of the slabs where torsional moments may occur. These minimizations are so more expressive as smaller are the widths of the slabs.
Numerical model analyses were done to predict probable displacements of the concrete face, which were then imposed to the slabs to obtain the respective stresses. All failures occurred in the central slabs caused from high compressive stresses, presenting an unknown behavior in such type of dam. The instrumentation of the embankment and of the concrete face should be intensified to reflect dam performance, mainly of its singularities. Help Fzce Find new research papers in: In other cases, leakages occurred by the failure of water stops due to excessive deformation.
Compressive stresses in the concrete face without joint MPa Figure 2 shows a map of the compressive stresses in the concrete face considering compressible joints in the region of the face A notable reduction in the the compressive stresses could be observed.
For this goal, studies should be developed with numerical models to estimate, from the very beginning of the design, the displacements and stresses in the dam.
Wetting of all the materials and in every zone should be done, not only in the upstream enrocameno, as usual. The basic principle stated by Cooke – Ref. Barry Cooke is invaluable.
This model must be dynamic, not only to define the zoning of the embankment as well as future adjustments, in function of the monitoring during the construction. Continuous compaction control, through equipments installed in the roller, could be an interesting measure to improve the control of the fill.
This model doesn’t consider the joints between the slabs of the concrete face. Figure 1 shows a map of horizontal compression stresses in the concrete face, fnrocamento the face without joints. However, it seems that his confidence in the stability of this type of dam regarding its resistance to normal operation loads and to the action of eventual water seepage led to adoption of some practical design criteria not totally applicable in very high dams built in narrow valleys, where stress levels extrapolated the already experienced values.
It is worth repeating the technical contribution of Mr. Remember me on this computer. Due to the result of the computations, double reinforcement mesh was adopted in large portion of the concrete face, contrary to the usual practice facs using a single mesh in the center of the face.
II SIMPÓSIO SOBRE BARRAGENS DE ENROCAMENTO
Cracks may occur in the concrete face; they would be tolerable since the embankment resists to the flow and the cracks can be easily sealed by placing fine material sandy silt.
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Barry Cooke died in In his works, Cooke states that the principle of precedents must be followed, but it cannot be restrictive to the progress, either for the implementation of higher dams or for the adoption of more cost-effective solutions.
Log In Sign Up. However, the larger compression stresses may not be only “horizontal” along the whole concrete face. His contribution in the development of this type of dam is invaluable, having participated of all Consultants Committees of CFRDs enrocametno in Brazil see Table 1 and practically of the construction of the main dams of this type around the world. The results should receive continuous analysis to barragehs the necessary actions in the design and in the constructive methods.
Except for the Salvajina dam, the others were built in narrow valleys. These dams, however, presented serious leakage and maintenance problems.
This would be an acceptable approach for CFRDs have intrinsic stability in function of the following features: Click here to sign up. He received many awards for his brilliant professional performance, such as the Distinguished Engineering Alumnus Award, from the University of Berkeley — California, and the Terzaghi Lecturer offrom the American Society of Civil Engineers. From toafter the good behavior observed in six dumped rockfill dams belonging to Pacific Gas and Electric Company USAwith heights between 23 and 45 m, higher dams were built, among them are the Salt Springs Dam USA and Paradela Dam Portugalwith heights of and m, respectively.
This study aims at presenting a discussion on the main factors of development of these stresses.
This prediction must take in place the geological-geotechnical features, the shape and topography of the valley and the properties of available construction materials. The rockfill embankment behavior is conditioned by several factors such as embankment zoning concfeto Oliveira — Ref. However, an ordered design approach is fundamental to guarantee an adequate performance of future high CFRD dams. These suggestions should be analyzed for each case.
Compressive stresses in the concrete face with 4 Enrovamento MPa These results show that compressible joints are effective to avoid the development of high compressive stresses. Compressive joints should be used in a way to allow the movement of the central slabs and relieve the compressive stresses among them.
In the decade of the of Foz do Areia Dam, in Brazil, was built with m of height, at that time the largest in the world. They presented a quite safety behaviorbut with significant leakages as they height increased up to 90m. At Campos Re Dam, built in a narrow valley, the displacements of the superficial benchmarks showed an accentuated move towards the center of the valley. It also presents reflections for criteria development for future design of very high CFRDs in order to avoid such failures.
The concern then changed from the perimetral joint to the tensile joints seals in abutment slabs. Thus, progressive modifications were introduced in the CFRD design, among them: