Seismic and structural health monitoring systems for large dams: theoretical, computational and practical innovations

Abstract

This paper is focused on the study of the dynamic behaviour of two large arch dams, and it presents some innovations for the improvement of Seismic and Structural Health Monitoring (SSHM) systems for dams. The work describes a methodology based on the integrated use of software for automatic monitoring data analysis and of computational 3D finite element (3DFE) models for dam dynamic behaviour simulation. The monitoring data analysis software was developed for automatic modal identification, in order to obtain natural frequencies and mode shapes, for automatic detection of vibrations induced by seismic events, to be distinguished from those caused by other operational sources, and for comparison between results retrieved from measured vibrations and numerical results from 3DFE modelling. The numerical simulations are carried out using a 3DFE program developed for dynamic analysis of dam-reservoir-foundation systems, based on a solid-fluid coupled formulation and considering the dam-water dynamic interaction, including calculation modules for complex modal analysis and for linear and non-linear seismic analysis. The case studies are two large arch dams that have been under continuous dynamic monitoring over the last ten years: Cabril dam (132 m high), the highest dam in Portugal, and Cahora Bassa dam (170 m high), in Mozambique, one of the highest dams in Africa. The SSHM systems installed in both dams have similar schemes and were designed to continuously record accelerations in several locations at the upper part of the dam body and near the dam-foundation interface, using uniaxial and triaxial accelerometers. The most significant experimental results from continuous dynamic monitoring are presented and compared with numerical results for both dams, with emphasis on the evolution of natural frequencies over time, including the vibration mode shapes for various water levels, and on the measured accelerations during low-intensity seismic events. Furthermore, the main results of non-linear seismic response simulations are provided, considering the effects due to joint movements and tensile and compressive concrete damage, aiming to assess the seismic performance of both dams based on the Endurance Time Analysis method.

The Role of Situatedness in Immersive Dam Visualization: Comparing Proxied with Immediate Approaches

“…This process is critical for ensuring the dam's safety and optimal functionality. It involves systematically tracking a range of parameters, each vital to the dam's stability and performance [4]. These parameters can encompass water levels, structural and foundational stresses, displacements within the dam and its foundation, movements in joints and cracks, as well as the measurement of environmental factors like air temperature.…”

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

“…Therefore, a continuous dam behavior assessment based on continuous monitoring data and modelling results is essential to verify structural safety for current and failure scenarios and thus to ensure the best operating conditions. With that aim, it is recommended the investment in continuous vibration monitoring systems, designed for seismic and structural health monitoring (SSHM), since the analysis of vibrations measured under ambient/operational conditions and during seismic events can provide valuable results to dam engineers and actionable data to help dam owners make informed decisions [1]. For example, experimental modal parameters can be used for dam behavior analysis, considering, e.g., the influence of reservoir water level variations, and most importantly for structural condition assessment, by detecting structural changes due to progressive concrete deterioration or damages caused by earthquakes.…”

Monitoring of the hydraulic units operation of the Sayano‐Shushenskaya hydroelectric power plant using remote seismic observations

“…[3][4][5][6][7] In the works of refs. [8][9][10][11][12] study of various dams using dynamic monitoring method is presented and various types of mathematical models and approaches are proposed to refine their frequencies and to determine existing defects. These studies [13][14][15][16][17] proposed options for monitoring engineering structures based on the accumulation and isolation of natural vibrations from the signal, as well as various approaches to interpretation and processing of the material.…”

“…In the works of refs 8–12 . study of various dams using dynamic monitoring method is presented and various types of mathematical models and approaches are proposed to refine their frequencies and to determine existing defects.…”