Advancing Tailings Dam Performance Monitoring with Distributed Acoustic Sensing
Date
2024-08-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Tailings dams require careful design, planning and monitoring throughout their life cycle to prevent a potential failure. Such failures can occur due to a variety of causes, such as overtopping, structural and foundation conditions, static or seismic liquefaction, and erosional processes. As such, a tailings dam monitoring system should be capable of identifying potential behaviours leading up to different failure modes and with adequate warning time. This thesis investigates an emerging fiber optic sensing technology, distributed acoustic sensing (DAS), with a passive geophysical technique (coda wave interferometry; CWI), to advance monitoring of tailings dam performance. The first study provides a proof-of-concept of CWI using geophones at an active tailings dam, from June to July 2020. Following this study, a fiber optic cable located near the geophones was then employed with DAS and CWI from April to August 2021. CWI was used to infer changes in shear wave velocities up to ~1.9% over depths ranging from ~6 to ~16 m. An inverse correlation between the dv/v and tailings pond levels in the summer months aligned with the earlier geophone study. This study demonstrated how DAS can augment traditional geotechnical monitoring by providing higher spatial resolution of dv/v as a proxy for dam performance. While higher frequency (> 1Hz) DAS measurements can be used with CWI, lower frequency (<1 Hz) DAS measurements can provide complementary information on changes in strain near the cable. A three-day low-frequency DAS dataset encompassing a rainfall event was acquired from the Hollin Hill slow-moving landslide observatory. A conceptual framework was developed to interpret the onset of movement, retrogression, and a flow lobe surge with nanostrain-rate sensitivity, providing new insights into the kinematics of a slow-moving landslide. Collocated slope inclinometer data correlated with the inferred DAS displacements. This study demonstrates how lower frequency DAS can also provide valuable information for tailings dam monitoring applications, using slope inclinometer data (commonly installed for tailings dam monitoring) to evaluate DAS performance. Together, these findings demonstrate how DAS can be used to advance monitoring of tailings dam performance to reduce the risk of future dam failures.
Description
Keywords
distributed acoustic sensing, tailings dams, geotechnical engineering, coda wave interferometry, passive seismic interferometry, distributed fiber optic sensing, environmental seismology
Citation
Ouellet, S. (2024). Advancing tailings dam performance monitoring with distributed acoustic sensing (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.