Critical aspects of using vibrating wire piezometers in geotechnical monitoring of dams: how to meet basic operating principles of the devices and avoid common errors that compromise monitoring


an appropriate amplitude, a good signal-to-noise ratio and remain within the sensor’s operational range. Parameters such as the electrical resistance of the coils and the thermistor can directly influence the accuracy of the measurements and, therefore, should be verified according to the manufacturers’ technical specifications. With advancements in technology and the standardization of monitoring procedures, it has become possible to systematically verify whether the sensor’s electrical signal meets the manufacturers’ specifications, ensuring proper instrument functioning and data reliability. Section 4 of this article presents the main technologies and recommended practices for the performance verification and fault diagnosis of vibrating wire piezometers..


2.2. Filter saturation process and importance for precision The filters of vibrating wire piezometers play a crucial role in accurately measuring pore pressures in soils, acting as an interface that allows water to pass through while blocking fine particles, thereby protecting the sensor’s diaphragm. For the filter to function properly, it must be fully saturated, without any air bubbles present. As highlighted by[13]


, the introduction of air into the system can dampen the vibration of the


wire and cause deviations in readings, a phenomenon known as “zero drift,” where the pressure reading gradually shifts over time. Figure 4 presents the three possible filter saturation conditions: unsaturated, where the chamber is completely filled with air; partially saturated, containing both water and air; and fully saturated, where the chamber is filled only with water. These conditions clearly illustrate how the level of saturation can influence the sensor’s response.


Figure 4. Representation of saturation conditions for a vibrating wire piezometer filter (Source: Adapted from[4]


)


Vol XXXIII Issue 3 | Dam Engineering | 109


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