DamPulse™ — Tailings Dam Monitoring System
DamPulse™, the integrated fibre optic sensing-based Tailings Dam Monitoring System, addresses issues of dam stability, public safety, and environmental protection.
Delivering ULTRA HD quality distributed temperature, strain, and acoustic measurements in real-time, the system offers early alerts of potential problems, minimizing the risk of dam failures.
Distributed fibre-optic monitoring offers dense spatial and temporal profiling over large sub-surface volumes, long ranges, and at locations where conventional point sensing is not applicable or not cost effective.
DamPulse enables operators to identify non-conformance with design or operational expectations to facilitate timely maintenance and intervention before any failure occurs.
The system provides high quality distributed temperature, strain, and acoustic measurements in real-time, with a single optical fibre cable over the entire structure. With multiple monitoring techniques it permits identification of increasing seepage zones, material changes and structural variations with high resolution.
- Enables entire dam structure to be efficiently monitored
- Unmanned operation
- Programmable alerts for abnormal or rapid changes in seepage, material density deformation, seismic activity or breach
- Real-time processing and visual presentation of data via web interface
Fully automated, remote monitoring
Enables the dams to be run with optimal efficiency.
No requirement from the operator to provide additional data.
Continuous, distributed sensing-based monitoring reveals even the smallest potential problems
Continuous, high-precision data acquisition allows trends to be identified, analysed over time and defects related to the performance captured at an early stage.
Continuous monitoring and/or imaging on demand
Continuous monitoring provides alarms of anomalous changes in the subsurface by combining temperature, strain and acoustic interpretations of the data. DAS data provide tomographic images to highlight physical variations in the dam.
Immediate insight into the structural health of the asset
Distributed fibre-optic sensing is a key technology that can be applied to monitor critical parameters for dam safety and environmental performance. Performance criteria can be selected for actionable alerts.
The system processes the high-resolution temperature, acoustic and strain data in real-time, detecting even minimal changes. In the case of a sudden change an alarm can be sent via SMS or E‑mail. This can prevent loss of life. It also provides invaluable environmental benefits as the system minimises the risk of catastrophes, potential tailings dam failures.
Providing early alerts, the system delivers financial benefits by avoiding high expenditure on remedial works.
Small environmental footprint
The system has a low-power requirement.
There are no maintenance costs associated with the fibre optic cable.
Surveillance of monitoring performance and quality check of cable
The system provides automatic warning of a cable break and the diagnostics allow the signal quality to be checked on demand.
Case Study: Seepage detection-based dam monitoring in Boliden, Sweden
Applications of Tailings Dam Monitoring Systems
With continuous monitoring of the temperature profile in the dam drainage system, seepage flow rates can be evaluated along dam with an alarm set for abnormal rates.
Using high-resolution Distributed Temperature Sensing (DTS) measurements, the system uses the natural seasonal temperature variations in the drainage system and reservoir to monitor changes in the seepage flow distribution, and identify, with precision, the location of internal erosion development. The sensor is the fibre-optic cable, no different from any telecoms type cable. The cable is permanently installed along the dam. High temperature resolution data is acquired with Silixa’s ULTIMA DTS™ continuously with fine spatial sampling.
The DTS data is processed using the XSeepT™ application developed by Hydroresearch and deployed today on over 70 embankment dams worldwide. XSeepT uses high spatial resolution temperature data from Silixa’s ULTIMA DTS to detect small seepage flow changes and to calculate seepage rates in a dam structure. Any change in the seepage flow rates can be an indication of erosion, one of the most common causes of dam failure.
The monitoring system evaluates the data in real-time and provides the operator with information locally or via a cloud application. Both temperature and seepage information are offered. Seepage data can be calculated and evaluated for each section of the dam.
XSeepT can export selected evaluated data to SCADA or ADAS and when sudden threshold changes are noticed alarm signal can be sent via *24V, E‑mail or SMS.
The system records acoustic data continuously or on demand to image the sub-surface through advanced seismic techniques. Variations in seismic velocity highlight any material changes in the dam to aid identification of internal erosion and increasing seepage rates at early stages.
Additional measurement techniques based on the same fibre-optic cable to map seepage below the drainage system are used to identify density changes in the dam and subsurface geology. These new monitoring techniques apply Distributed Acoustic Sensing (DAS) using both passive and active seismic methods.
Seismic surveys can be active (use of external energy sources) or passive (analysis of natural noise or seismic events). Active seismic surveys can be used to image the subsurface, applying techniques such as multi-channel analysis of surface waves (MASW) and other tomographic methods.
Applying passive ambient noise interferometry (ANI), where recordings of background noise are used to reconstruct waves travelling between two receivers, a dam can be imaged with high precision.
Through continuous and/or on-demand recording seismic activity due to movement in/below the dam can be monitored and assessed.
Seismic activity – Distributed Acoustic Sensing (DAS)
Small seismic events, termed microseismicity, caused by movement on fractures or faults, can also be detected using DAS technology. DAS microseismic monitoring can be used to detect seismic movement in dams or induced seismicity in the area surrounding dams where seismic hazard is often an important safety consideration.
Through continuous monitoring of strain and seismic activity, any movement, deformation or subsidence can be detected with high spatial resolution at early stages.
Distributed Strain Sensing
Detection of movement
Using DSS, local movements can be detected at an early stage if the cable is well coupled to the soil and movement is effectively transferred to the cable. This provides useful and additional information to the survey points which are normally used to detect movements.
Temperature compensation is achieved in combination with DTS measurements.
A combination of dynamic and static strain changes offers a better understanding of potential structural changes and make early decision-making possible. The system can detect strain changes (movement changes) in the dam and can therefore be used either as early-warning system with continuous monitoring, or as an investigation tool to measure movements regularly. Measured strain differences correspond to movement perpendicular to the cable. Local soil properties and water content influence the friction between the cable and the soil and change the length over which the movement will occur. However, the central point will be unaffected.
Dam breach verification provides alerts of the time and location of sudden failures in the embankment. The continuity of the sensing cable is checked continuously.
DAS, DSS and DTS are capable of detecting a fibre breach location. Using purpose built software, it is also possible to analyze the signal losses along the full length of the cable. Temporal signal loss changes can then be detected before a full cable breach will occur.
Detection of signal losses is often used during installation to ensure a correct installation of the cable. This is recommended at all installations, if possible, to identify any damage on the fibre. Damages are mostly caused by local deformation around boulders or local movements (insufficient compaction) resulting in a small bending radius of the cable. In such cases the cable can carefully be exposed, and carefully stretched out and placed back in the trench and backfilled.