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
4. Data logger configuration: It is crucial to verify that the frequency-to-pressure conversion formulas and correction coefficients in the dataloggers are consistent with the calibration certificates of the installed sensors. Misconfigured systems can lead to errors that compromise the monitoring system’s reliability.
Practical recommendations:
• Initial calibration: Before installation, ensure the piezometer is calibrated, and the correction coefficients are accurately set in the datalogger.
• Zero readings: Perform baseline readings under controlled conditions after thermal equilibrium to establish reference values for accurate comparisons.
• Inspection and maintenance: Periodically inspect sensor components, including cables and connections, and perform electrical resistance checks to identify potential issues early.
• Noise mitigation: Use shielded cables and place sensors away from interference sources. In high- noise environments, apply spectral analysis tools to improve data accuracy.
• Deaerated water use: When filling the piezometer, use deaerated water to prevent air bubbles, which can affect pressure readings, particularly in saturated soils.
By following these best practices, industry professionals can ensure the precision, consistency, and longevity of VW piezometers, reinforcing the safety and effectiveness of geotechnical monitoring programs. This integration of proper installation, calibration, and diagnostic techniques enhances the overall performance of dam safety instrumentation systems and aids in preventing critical structural failures.
References
[1] International Commission on Large Dams (ICOLD). (2018). Bulletin 158: Dam Surveillance Guide, Chapter 9. Paris: ICOLD.
[2] Marinaro, R. A. (2022). Methodology Proposal for Defining Instrumentation Control Levels Associated with Failure Modes: A Case Study in a Tailings Dam (Master’s Thesis). Graduate Program in Geotechnical Engineering, Federal University of Ouro Preto.
[3] Penna, D., Marinaro, R., Lopes, M., & Carmo, A. (2017). Risk Map as a Tool for Dam Safety Management. Belo Horizonte, pp. 1–15.
[4] GEOKON. (n.d.). Model 4500 Series Vibrating Wire Piezometer. Retrieved from
https://www.geokon. com/4500Series
[5] Encardio-Rite. (n.d.). Users’ Manual: Vibrating Wire Piezometer EPP-30V, EPP-40V, EPP-50V. Retrieved from
https://www.encardio.com/uploads/manual/EPP-30v_40v_50v-Piezometer-.pdf
[6] RST Instruments Ltd. (2020). VW2106 Vibrating Wire Readout Manual (ELM0042M). Coquitlam, BC, Canada: RST Instruments Ltd.
[7] Geosense. (n.d.). Piezometers Indepth V10.
[8] Soil Instruments. (n.d.). VWnote User Manual (Man230 VWnote – MN1114 – Rev1.2.0). United Kingdom: Soil Instruments Limited.
[9] Mikkelsen, P. E., & Green, G. E. (2003). Pore Pressure Monitoring with Fully Grouted Vibrating Wire Piezometers. Canadian Geotechnical Journal. [10] U.S. Army Corps of Engineers (USACE). (2014). Engineer Manual: Design and Construction of
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