Seismic and Structural Health Monitoring of Dams in Portugal

Oliveira, Silvia Paula De; Alegre, André

doi:10.1007/978-3-030-13976-6_4

Cited by 17 publications

(11 citation statements)

References 2 publications

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“…With a view to address the concerns about long-term safety, Cabril dam was instrumented in 2008 with a pioneering SSHM system, developed to monitor dam behavior under ambient/operational conditions and to measure the response during seismic events [4][5][6]. The system was designed to continuously measure vibrations on the dam, using a) 16 uniaxial accelerometers to record accelerations along the upper part of the dam, 9 in the upper gallery, at el.…”

Section: Case-study: Cabril Dam Portugalmentioning

confidence: 99%

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

OLIVEIRA,

ALEGRE,

RAMOS

et al. 2023

Proceedings of the 14th International Workshop on Structural Health Monitoring

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This paper presents a complete study on the dynamic behavior of the 132 m high Cabril arch dam (Portugal). In operation for almost 70 years, horizontal cracks appeared on the downstream face after the first reservoir filling, and in the 1980s the dam started showing signs of concrete swelling. To address the concerns about its long-term safety, a pioneering continuous vibration monitoring system, designed for Seismic and Structural Health Monitoring, was installed in Cabril dam in 2008. In this work, the vibrations recorded under ambient/operational conditions for more than a decade are analyzed to estimate the modal parameters of the dam, which are then used to calibrate and validate a finite element model of the dam-reservoir-foundation system with the horizontal cracking. After that, the dynamic behavior of Cabril dam is simulated for the next decades, considering a computationally generated scenario of progressive damage due to concrete swelling. The results show that a) the dynamic behavior of Cabril dam is not being affected by the existing swelling phenomenon, and b) vibration-based analysis can be effective for detecting structural changes due to progressive damage. Lastly, the calibrated model is adapted for conducting non-linear seismic simulations, considering joint movements and tensile and compressive concrete damage. A method based on Endurance Time Analysis method is applied to assess the seismic safety of the dam with respect to the Operating Basis Earthquake and the Safety Evaluation Earthquake. The results confirm that Cabril dam can withstand accelerations several times greater than both earthquake levels, showing its adequate seismic capacity.

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Section: Case-study: Cabril Dam Portugalmentioning

confidence: 99%

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

OLIVEIRA,

ALEGRE,

RAMOS

et al. 2023

Proceedings of the 14th International Workshop on Structural Health Monitoring

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show abstract

“…The authors concluded that electro-mechanical impedance based on PTZ (pan-tilt-zoom) sensors (based on the perspective distortion correction method and also can increase the monitoring range) can detect the seismic damage and the model can measure the damage level. Another study explored the seismic and structural health of the Baixo Sabor dam and Cabril dam in Portugal and modeled them using the 3D FE method [140]. A 2D FE model was applied [141] to assess the impact of an earthquake on the Sefidrud buttress dam potential failure zone.…”

Section: D Dam Modelingmentioning

confidence: 99%

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Yaseen‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

Ameen

Aldlemy

et al. 2020

Sustainability

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Dam and powerhouse operation sustainability is a major concern from the hydraulic engineering perspective. Powerhouse operation is one of the main sources of vibrations in the dam structure and hydropower plant; thus, the evaluation of turbine performance at different water pressures is important for determining the sustainability of the dam body. Draft tube turbines run under high pressure and suffer from connection problems, such as vibrations and pressure fluctuation. Reducing the pressure fluctuation and minimizing the principal stress caused by undesired components of water in the draft tube turbine are ongoing problems that must be resolved. Here, we conducted a comprehensive review of studies performed on dams, powerhouses, and turbine vibration, focusing on the vibration of two turbine units: Kaplan and Francis turbine units. The survey covered several aspects of dam types (e.g., rock and concrete dams), powerhouse analysis, turbine vibrations, and the relationship between dam and hydropower plant sustainability and operation. The current review covers the related research on the fluid mechanism in turbine units of hydropower plants, providing a perspective on better control of vibrations. Thus, the risks and failures can be better managed and reduced, which in turn will reduce hydropower plant operation costs and simultaneously increase the economical sustainability. Several research gaps were found, and the literature was assessed to provide more insightful details on the studies surveyed. Numerous future research directions are recommended.

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“…One of the key indicators of a dam's dynamic behaviour and structural health is its modal parameters, namely the natural frequencies and corresponding mode shapes. These parameters are sensitive indicators of possible changes in the dam's stiffness and mass properties, which could be caused by several factors such as reservoir variations [1][2][3], thermal variations [4,5], and progressive deterioration phenomena [6,7]. Therefore, it is important to monitor the evolution of the natural frequencies of the dam over time and to evaluate the effect of each of the referred factors separately on the dam response.…”

Section: Introductionmentioning

confidence: 99%

Cahora Bassa vibrations monitoring between 2010-2022. Analysis of frequencies using HST statistical models for effects separation

Oliveira,

Mendes,

Rodrigues

et al. 2024

J. Phys.: Conf. Ser.

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Cahora Bassa dam is a 170m-high arch dam located in western Mozambique. In operation for almost 50 years, since 1974, the dam is affected by a swelling process of small/medium amplitude. Aiming to control its structural health over time, in 2010 the dam was instrumented with a continuous vibrations monitoring system, designed for Seismic and Structural Health Monitoring (SSHM), which includes 10 uniaxial accelerometers in the crest gallery and 3 triaxial accelerometers in the dam-foundation interface. The latest results on the dynamic behaviour monitoring of the dam are presented, namely the evolution of the main natural frequencies over time and the corresponding mode shapes. Then, HST statistical models for separation of effects, considering the hydrostatic pressure (H), seasonal variations (S), and time (T) dependent factors, are used to analyse the evolution of the experimental natural frequencies over the last 12 years. The achieved results show that the dynamic behaviour of the dam is mostly influenced by the water level variations. However, a very small decreasing tendency of the natural frequency values was detected, which may indicate a slight decrease of the global stiffness of the dam, possibly due to the evolution of the concrete swelling pathological process.

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Seismic and Structural Health Monitoring of Dams in Portugal

Cited by 17 publications

References 2 publications

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

Dynamic Behavior of Cabril Dam: Finite Element Model Calibration, Structural Health Monitoring (2008–2023) and Seismic Safety Assessment

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Cahora Bassa vibrations monitoring between 2010-2022. Analysis of frequencies using HST statistical models for effects separation

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