Creep of Dam Concrete Evaluated from Laboratory and In Situ Tests

Serra, Carlos; Batista, A. L.; Castro, A. Tavares de

doi:10.1111/j.1475-1305.2011.00818.x

Cited by 11 publications

(14 citation statements)

References 14 publications

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“…2 General view of the active and non-stress creep cells and of the loading system dam concrete and its large aggregates, since the surrounding mass concrete is used as the reaction frame. This type of experimental installation was developed in the past by the National Laboratory for Civil Engineering (LNEC) [77,78] and, for this particular study, several technical improvements were implemented. The main new features are: (i) the use of a standard flat-jack (with rigid interface platens), larger in diameter (/) and increasing the /-MSA ratio of dam concrete specimen (Fig.…”

Section: Experimental Setup For In Situ Testing Using Creep Cellsmentioning

confidence: 99%

Dam and wet-screened concrete creep in compression: in situ experimental results and creep strains prediction using model B3 and composite models

2016

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This paper proposes a methodology for the prediction of the compressive creep strains of dam concrete based on wet-screened experimental results at constant elevated temperature conditions measured in situ. Due to its large aggregate dimensions, the experimental characterization of dam concrete has particular constraints. The wet-screened concrete, obtained by sieving the aggregates larger than a given dimension, after mixing, is used to cast standard specimens and to embed monitoring devices. An experimental in situ installation using creep cells was used to obtain the compressive creep strain development over time for the maturing conditions of the dam core. The study of the effect of wet-screening procedure on creep in compression considers three types of concrete, dam concrete and two wet-screened concretes tested at three loading ages, 28, 90 and 365 days. The comparison between different types of concrete at different maturing conditions requires the definition of a reference state given by the maturity method, using the equivalent age, and relies on the fit of compressive creep strains to the RILEM recommended model B3. To take into account the effect of the aggregate content on the deformability properties of dam concrete, an equivalent two-phase composite model was applied. The equivalent composite model considered the equivalent matrix as the wet-screened concrete and the inclusions as the larger aggregates that are removed during the wet-screening procedure. Predictions obtained with the composite model are close to the dam concrete experimental results, for the tested loading ages.

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Section: Experimental Setup For In Situ Testing Using Creep Cellsmentioning

confidence: 99%

Dam and wet-screened concrete creep in compression: in situ experimental results and creep strains prediction using model B3 and composite models

2016

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“…Although sometimes this deformation can be negligible for operation periods, 11 it is an important predictor for initial impoundment periods. [15][16][17] All published mathematical expressions of the time-dependent deformation are monotonically increasing functions with time. 3,6,11,12 However, in accordance with the detailed studies, this deformation does not always conform to the assumption of the monotonically increasing functions.…”

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confidence: 99%

Statistical modelling for high arch dam deformation during the initial impoundment period

2020

Struct Control Health Monit

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Although statistical models are efficient in most cases to analyze concrete dam displacements, these models are built on several hypotheses, leading to uncertainties especially for special periods. The special statistical models, improving estimations of the non-stationary thermal and the non-monotonic timedependent effects, are proposed for the displacements of high arch dams during their initial impoundment periods in this paper. The hierarchical clustering on principal component analysis is developed to divide thermometers into groups and to choose representative thermometers or identify major principal components on measured temperature data to represent the non-stationary thermal effect on dam's displacements. The non-monotonic formula for the time-dependent deformation, emphasizing the creep and its restoration of dam concrete and its surrounding rock, is derived and further simplified when the reservoir water level exhibits an evident periodicity. Then, two improved statistical models accounting for these non-stationary thermal and non-monotonic time-dependent effects are proposed. The proposed statistical models with clear physical meanings are applied to investigate the measured displacements of the Xiluodu arch dam. Model performance comparisons indicate that the proposed models have significant improvement in fitting precision and prediction ability over the traditional and more recent models. Model results confirm the influence of reservoir thermal stratification and concrete temperature rise on the thermal displacement, and the non-monotonic effect on the timedependent displacement. The proposed models yield to a better identification of the deformation mechanism for high arch dams during their initial impoundment periods. K E Y W O R D S clustering, dam, initial impoundment period, principal component analysis, structural health monitoring, time-dependent effect 1 | INTRODUCTION A number of super high arch dams of 200-300 m high have been built in China. Many of these dams have entered or will enter their initial impoundment periods. 1 Super high dams have strong interactions with air and water temperature, reservoir water level, uplift, rock deformability, and so on. During the initial impoundment period, a super high

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“…The process is shown in Figure 3. The integral Young modulus E of the dam can be obtained by using testing instruments or through the mathematical model for inverse analysis as shown in Equation (20).…”

Section: Parameter Identification Of Concrete Dammentioning

confidence: 99%

“…The dam body is constructed out of concrete and other man‐made material whose properties can be artificially controlled. Generally, the mechanical properties of the dam body can be measured through laboratory field tests . On the other hand, the geological conditions at the foundation are complicated and changes after impoundment.…”

Section: Introductionmentioning

confidence: 99%

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A deformation separation method for gravity dam body and foundation based on the observed displacements

Lin

Liu

et al. 2018

Struct Control Health Monit

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Summary The displacement at arbitrary point in the dam is composed of two parts: One is the elastic deformation of dam body and the other that is due to the constrained deformation of foundation. The two parts should be separated to obtain reliable information reflecting the different characteristics of dam body and foundation. A simplified simulation method for gravity dam foundations is proposed that reflects the constrained deformation of foundation in a rational manner while taking into account the complex and diverse mechanical properties. Only the effects of the foundation on dam is investigated in the proposed model, and they are considered either centralized constraints or distributed constraints. The solution of the global foundation deformation is based on the monitoring displacements at measuring points in the gravity dam section using the hybrid partition finite element–interface boundary element approach. The reaction of the foundation on dam can be reflected by the global foundation deformation and the constrained force at dam bottom. On the basis, the whole dam response under a given load combination can be estimated using finite element theory. Three analyses have been performed on a typical gravity dam section to verify the feasibility of simplified simulations for different foundations as well as to allow for discussions regarding the differences among the simulations. An example analysis based on the proposed method is performed on a prototype gravity dam, and the results, which compared with actual measurements for discussions, show that the proposed method is reasonable and practical.

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Creep of Dam Concrete Evaluated from Laboratory and In Situ Tests

Cited by 11 publications

References 14 publications

Dam and wet-screened concrete creep in compression: in situ experimental results and creep strains prediction using model B3 and composite models

Dam and wet-screened concrete creep in compression: in situ experimental results and creep strains prediction using model B3 and composite models

Statistical modelling for high arch dam deformation during the initial impoundment period

A deformation separation method for gravity dam body and foundation based on the observed displacements

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