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


Figure 2. Classical experiment using tuning forks Similarly, in a vibrating wire piezometer, when the wire is excited at its resonance frequency, the reflected


signal reaches its highest amplitude at that specific frequency, enabling precise measurement. This allows for the subsequent application of correlation formulate to calculate the pressure and, consequently, determine the height of the water column at the monitored point. In addition to the vibrating wire and diaphragm, the piezometer includes other essential components, as illustrated in Figure 3. The porous filter, located at the sensor’s tip, allows water to pass through while preventing fine particles from entering the device, protecting the diaphragm from clogging. The excitation and reading coils are responsible for generating and detecting the vibration signal, while the thermistor measures the temperature, enabling pressure values to be corrected for thermal variations. The instrumentation cable transmits the signal, ensuring both the electrical excitation of the wire and the collection of data for analysis.


Figure 3. Schematic of the vibrating wire piezometer and its main components (Source: Adapted from[4]


)


To ensure the reliable operation of the sensors, certain procedures are essential, such as the proper saturation of the porous filter and the execution of the initial reference reading (known as the “zero” reading), which is detailed in sections 2.2 and 2.3, respectively. Proper saturation prevents air from entering the sensor chamber, a factor that can compromise measurement accuracy. Another crucial aspect is the ability of the reading and excitation equipment to generate electrical signals that match the sensor’s frequency range. The signal captured by the readout or datalogger must have


108 | Dam Engineering | Vol XXXIII Issue 3


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