Wellerson Bastos, Marcos Pimenta Filho, Luiza Almeida, Marina Ferreira & Mauro Santos Junior


inspection should also confirm that thermal and barometric correction coefficients are up to date in the datalogger or readout to avoid systematic errors. Finally, the correct application of correction factors and the validation of conversion equations ensure that vibrating wire piezometers provide precise and representative measurements. Adopting best practices and advanced signal analysis technologies reinforces the reliability of the monitoring system, enabling safe and effective tracking of geotechnical structures.


4. Verification Resources and Parameters


4.1. Available reading and diagnostic technologies The accuracy of measurements obtained from vibrating wire piezometers directly depends on the reading technologies and diagnostic resources of field devices. These devices convert the resonant frequency of the vibrating wire into engineering units, such as pressure or displacement, and are essential for identifying anomalies that could compromise data reliability. With technological advancements, modern devices offer tools not only for reading but also for detailed signal quality analysis, ensuring reliable measurements in geotechnical monitoring campaigns. One of the key monitored parameters is the analysis of the vibrating wire’s frequency. The traditional


approach consists of time-domain analysis, where the frequency is calculated based on zero-crossings within a given time interval. Devices such as the VW2106 and the GK-404 use this method, which, despite its efficiency, is susceptible to low and medium-frequency noise from external sources, such as power grids and engines. To mitigate these effects, more advanced equipment, such as the GK-406 and VWAnalyzer, uses VSPECT™


technology, which applies Fourier transforms to convert the signal into a frequency spectrum, enabling precise identification of the dominant frequency even in environments with high electromagnetic interference. In Figure 6, two examples of signals in the time domain and frequency spectrum are presented, illustrating the differences between a clean signal and one with interference:


Figure 6. Graphical representation of signals in vibrating wire piezometers (Source:[20]


Figure 6 highlights that, in an ideal signal, the frequency spectrum presents a clear and isolated peak (an indicator of an accurate reading), while a signal with interference shows multiple peaks (markers 25 to 27),


116 | Dam Engineering | Vol XXXIII Issue 3


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