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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These modifications were successfully introduced in dams built in Brazil and in the world; however, all of them with height below m the height of Foz do Areia dam. At Campos Novos Dam, built in a narrow valley, comcreto displacements of the superficial benchmarks fcae an accentuated move towards the center of the valley.
Continuous concretl control, through equipments installed in the roller, could be an interesting measure to improve the control of the fill. 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.
Wetting of all the materials and in every zone should be done, not only in the upstream third, as usual.
The rockfill embankment behavior is conditioned by several factors such as embankment zoning see Oliveira — Ref. Such failures motivated the abandonment of this type of solution for dams until when, with the development of heavy vibrating rollers for compaction of rockfill in layers, high rockfill dams with clay core started to be built.
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.
Compressive joints should be used in a way to allow the movement of the central slabs and relieve the compressive stresses among them. 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.
This dam, built in open valley, has been showing excellent performance, and was a reference. This study aims at presenting a discussion on the main factors of development of these stresses. 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.
This prediction must take in place the geological-geotechnical features, the shape and topography of the valley and the properties of available construction materials. They presented a quite safety behaviorbut with significant leakages as they height increased up to 90m.
II SIMPÓSIO SOBRE BARRAGENS DE ENROCAMENTO
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.
All failures occurred in the central slabs caused from high compressive stresses, presenting an unknown behavior in such type of dam.
This model doesn’t consider enrpcamento joints between the slabs of the concrete face. Compressive stresses in the concrete face with 4 Joints MPa These results show that compressible joints are effective to avoid the development of high compressive stresses. It is worth repeating the technical contribution of Mr. Except for the Salvajina dam, the others were built in narrow valleys.
However, the larger compression stresses may not be only “horizontal” along the whole concrete face. Cracks may occur d 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.
Flávio Alberto Crispel
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. These minimizations are so more expressive as smaller are the widths of the slabs. Barry Cooke died in 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.
The instrumentation of the embankment and of the df face should be intensified to reflect dam performance, mainly of its singularities. From toafter the good behavior observed in six dumped rockfill co, 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.
Due to the result of the computations, double reinforcement mesh was adopted in large portion of the concrete face, contrary to the usual practice of using a single mesh in the center of the face. 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.
However, an ordered design approach is fundamental to guarantee an adequate performance of future high CFRD dams. 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.
On cooncreto other hand, the tensile joints seals of the slabs on the abutments regions should be capable to absorb the largest displacements garragens from the compression of the joints in the central area. It also presents reflections for criteria development for future design of very high CFRDs in order to avoid such failures.
The results should receive continuous analysis to allow the necessary actions in the design and in the constructive methods. Skip to main content.
Flávio Alberto Crispel
In other cases, leakages occurred by the failure of water stops due to excessive deformation. The basic principle stated by Cooke – Ref. Figure 1 shows a map of bxrragens compression stresses in the concrete face, considering the face without joints.
Barry Cooke is invaluable.
Click here to sign up. However, some of these dams presented infiltration problems. 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.
His contribution in the development of this type doncreto dam is invaluable, having participated of all Consultants Committees of CFRDs built in Brazil see Table 1 and practically of the construction of the main dams of this type around the world. The concern then changed from the perimetral joint to the tensile joints seals in abutment slabs. Such width reduction would also restrict the area of the slabs where torsional moments may occur.