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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Compressive joints should be used in a way to allow the movement of the central slabs and relieve the compressive stresses among them.
Flávio Alberto Crispel
Such width reduction would also restrict the area of the slabs where torsional moments may occur. Narragens would be an acceptable approach for CFRDs have intrinsic stability in function of the following features: However, some of these dams presented infiltration problems.
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 facf narrow valleys, where stress levels extrapolated the already experienced values.
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. 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.
The rockfill embankment behavior is conditioned by several factors such as embankment zoning see Oliveira — Ref.
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. In other cases, leakages occurred by the failure of water stops due to excessive deformation. For a more favorable behavior in relation to these efforts, fafe concrete face should be divided into panels that can reduce or eliminate some of the soliciting efforts above mentioned.
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. The results should receive continuous analysis to allow the necessary actions in the design and in the comm methods. The concern then changed from the perimetral joint to the tensile joints seals in abutment slabs.
They presented a quite safety behaviorbut with significant leakages as they height increased up to 90m.
REFLECTIONS ON NEW DESIGN OF VERY HIGH Concrete face rockfill dams | Ciro Humes –
The success of these dams, with heights of up to m Chicoasen Dam, in Mexicorestarted the construction of concrete face rockfill dams, attractive for their lower cost and shorter time of construction when local rain fall conditions are restrictive for soil compaction. 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.
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. This prediction must take in place the geological-geotechnical features, the shape and topography of the valley and the properties of available construction materials. This model doesn’t consider the joints between the slabs of the concrete face.
Help Center Find new research papers in: The basic principle stated by Cooke – Ref. This study aims at presenting a discussion on the main factors of development of these stresses. However, the larger compression stresses may not be only “horizontal” along the whole concrete face.
Cracks may occur in the concrete face; they would enrocameento tolerable since the embankment resists to the flow and the cracks can be easily sealed by placing fine material sandy silt.
These suggestions should be analyzed for each case. 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 barragenz for the adoption of more cost-effective solutions.
Enrodamento Cooke is invaluable. 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. Wetting of all the materials and in every zone should be done, not only in the upstream third, as usual. Thus, progressive modifications were introduced in the CFRD design, among them: Continuous compaction control, through equipments installed in the roller, could be an interesting measure to improve the control of the fill.
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Flávio Alberto Crispel
It must be pointed out that this feature is entocamento on abutments. This dam, built in open valley, has been showing excellent performance, and was a reference. 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.
These minimizations are so more expressive as smaller are the widths of the slabs. Click here to sign up. 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, an ordered design approach is fundamental to guarantee an adequate performance of future high CFRD dams.
Remember me on this computer. Barry Cooke died barrafens It is worth repeating the technical contribution of Mr. Except for the Salvajina dam, the others were built in narrow valleys. Figure 1 shows a map of horizontal compression stresses in the concrete face, considering the face without joints.
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. 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.
The instrumentation of the embankment and of the concrete face should be intensified to reflect dam performance, mainly of its singularities. Log In Sign Up. All failures occurred in the central slabs caused from high compressive stresses, presenting an unknown behavior in such type of dam. These dams, however, presented serious leakage and maintenance problems. 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.
At Campos Novos Dam, built in a narrow valley, the displacements of the superficial benchmarks showed an accentuated move towards the center of the valley. 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.