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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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 condreto m, respectively. Except for the Salvajina dam, the others were built in narrow valleys.
In other cases, leakages dace by the failure of water stops due to excessive deformation. Log In Sign Up. His contribution in the development of this type of 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.
This study aims at presenting a discussion on the main factors of development of these stresses. 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.
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.
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. Compressive stresses in cooncreto 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 engocamento the compressive bareagens could be observed. This prediction must take in place the geological-geotechnical features, the shape and topography of the valley and the properties of available construction materials.
Thus, progressive modifications were introduced in cocnreto CFRD design, among them: Remember me on this computer. The instrumentation of the embankment and of the concrete face should be intensified to reflect dam performance, mainly of its singularities. These suggestions should be analyzed for each case. Skip to main content. However, enrocameento ordered design approach is fundamental to guarantee an adequate performance of future high CFRD dams.
Due to the result of bxrragens 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. This dam, built in open valley, has been showing excellent performance, and was a reference.
It must be pointed out that this feature is critical on abutments. These minimizations are so more expressive enrocamejto smaller are the widths of the slabs. This model doesn’t consider the joints between the slabs of the concrete face.
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.
These dams, however, presented serious leakage and maintenance problems. He received many awards for his brilliant professional performance, such as the Distinguished Engineering Alumnus Award, from the University of Berkeley — California, and cincreto Terzaghi Lecturer offrom the American Society of Civil Engineers. Barragen would be an acceptable approach for CFRDs have intrinsic stability in function of the following features: It also presents reflections for criteria development for future design of very high CFRDs in order to avoid such failures.
Continuous compaction control, through equipments installed in the roller, could be an interesting measure to improve the control of the fill. 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.
II SIMPÓSIO SOBRE BARRAGENS DE ENROCAMENTO
Compressive joints should be used in a way to allow the movement of the central slabs and relieve the compressive stresses among them.
They presented a quite safety behaviorbut with significant leakages as they height increased up to 90m. The basic principle stated by Cooke – Ref. Click here to sign up. The rockfill embankment behavior is conditioned by several factors such as embankment zoning see Oliveira — Ref. It is worth repeating the technical contribution of Mr.
The concern then changed from the perimetral joint to the tensile joints seals in abutment 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.
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. 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.
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. The success of these dams, with heights of up to m Chicoasen Dam, in Mexicorestarted the construction of concrete face rockfill dams, barragdns for their lower cost and shorter time of construction when local rain fall conditions are restrictive for soil compaction.
Barry Cooke is invaluable.
The results should receive continuous analysis to allow the necessary actions in the design and in the constructive methods.
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.
Help Center Find new research papers in: However, the larger compression stresses may not be only “horizontal” along the whole concrete face. Wetting of all the materials and in every zone should be done, not only in the upstream third, as usual.
Flávio Alberto Crispel
For a more favorable behavior in barragwns to these efforts, the concrete face should be divided into panels that can reduce or eliminate some of the soliciting efforts above mentioned. 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.
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.