2020 – Demonstrating risk benefits of improved monitoring and surveillance
Hench Wang, Peter Hill, Sam Banzi, Muhammad Hameed
Dam owners can often struggle to demonstrate the dam safety risk benefits that can be achieved through non-structural risk reduction measures, such as adoption of smart technological solutions that improve the timeliness and quality of decision making. WaterNSW collaborated with HARC to develop a novel way of demonstrating benefits from improved data management. This paper discusses the use of HEC-LifeSim to demonstrate the reduction in life safety risk from improved monitoring through DamGuard for a case study dam in Sydney. DamGuard is a real-time dam safety monitoring system implemented by WaterNSW. This case study was the first time in Australia where a simulation model such as HEC-LifeSim was applied to quantify the life safety risk benefits pre and post the implementation of DamGuard. The implementation of DamGuard to the sample dam was estimated to reduce the life safety risk by 15%.
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2020 Papers
Cloud-Based Monitoring of Geotechnical Structures– Case Study: Hinkley Point Nuclear Power Plant
Learn moreMatthias WILD, James STEWART, Chris IRVIN, Sander Van Ameijde
The awareness of safe and sustainable utilisation of all forms of construction such as bridges, tunnels, dams or industrial buildings during its whole lifetime is increasing more and more. The safe operation of our dams is of critical importance to society. As our assets age, the focus on monitoring, control systems and lifespan management is of increasing importance. Communities need to have peace of mind these assets are not going to fail. To prevent failures of structures, a common method is for periodical or situational site visits to check the crucial points of construction. Site visits are cost intensive, subjective and non-continuous. This results in a global research focus on measurement devices and evaluation systems to generate a full structural health monitoring system which guarantees measurement and data evaluation adapted for the specific application over the full lifespan.
For important structures like the Hinkley Point nuclear power plant or Australian Dam structures it’s not just the inspection costs and a sustainably utilisation during service life that are important. The safety during operation of the nuclear power plant is also critical to its operation. To monitor the deep excavation at the power plant DYWIDAG provided geotechnical systems combined with measurement sensors and a monitoring concept for the lifespan of the structure. About 14,000 soil nails and bar anchors are stabilising the excavation. Movements of the retaining wall will lead to a change of stress in the geotechnical tension members. This change is monitored by DYNA-Force Sensors, which are used for load monitoring. This monitoring system has been used successfully in a range of critical structures like stadium roof-beams, staycables, dam-anchors with strands or bars.
A simple installation and read out of sensors is not a major facilitation compared to site visits. The implementation of sensors in a sophisticated monitoring system is the big advantage of structural health monitoring which guarantees a safe and sustainable utilisation of the construction. DYWIDAG is making infrastructure lifespan management smarter and offers a cloud-based online sensor management system (Platform Interactive) which enables processing of large volumes of sensor data and performing complex calculations. It provides real-time alerting, presenting the information in an innovative and interactive way, removing subjective interpretation and providing numerical data online in real time. Platform Interactive with plug and play pre-configured sensors, may also be adapted and applied for a range of SHM projects. It provides continuous reporting and the reassurance structures are performing as they should without the possibility of failure. At DYWIDAG we are making infrastructure lifespan management smarter, safer, stronger
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2020 Papers
2020 – Monte Carlo Geospatial Approach to Liner Design Principles in TSFs
Learn moreGideon Steyl, Ralph Holding, Lis Boczek
A Monte Carlo method for assessing liner systems is applied with outcomes demonstrating the range of discharge that could occur over the liner interface. The Monte Carlo approach allows for variation of fill material over the liner system and includes the assessment of a second compacted zone either above or below the liner zone. In this paper clay liners were evaluated due to regulatory guidelines and it could be demonstrated that similar performance to a 1 m clay liner could be attained using compacted material to reduce discharge over the liner interface. The approach applied in this paper allows for at least a worst-case quantification of seepage risk which could be included in liner selection criteria or presenting liner options to regulators.
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2020 Papers
2020 – A novel approach to defect mapping and condition monitoring of large dams using drones and digital engineering
Learn moreZack Wasson
The confluence of several technological innovations including drones, photogrammetry, and thermal imaging has enabled the development of a novel approach to defect mapping and monitoring for large dams. A pilot project trialling the methodology was completed at a rockfill embankment dam with a concrete spillway and is presented as a potential means of improving the accuracy and reliability of condition monitoring. The pilot project included two main objectives: digital inspection and mapping of defects within the concrete spillway; and drone-based photogrammetric survey of the rockfill embankment. Defect mapping of the concrete spillway utilised drone-based photography and Structure from Motion (SfM) photogrammetry to develop a high-fidelity 3D model, from which visual defects could be identified and mapped in a virtual environment. Thermal infrared (IR) imagery of the structure provided an indication of potential shallow subsurface defects in the concrete. Photogrammetric survey of the embankment structure utilised drone-based photography, SfM photogrammetry and a network of precisely surveyed ground control and verification points to develop a georeferenced point cloud, digital elevation model and elevation contours. The results of the project were delivered via a web-based digital twin which included georeferenced results from defect mapping, aerial survey and tools for visualisation, measurement, and reporting.
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2020 Papers
2020 – Use of Conditional Mean Spectra with Minimum Magnitude less than 5 in Seismic Hazard Analysis
Learn morePaul Somerville, Andreas Skarlatoudis, Jeff Bayless, Polly Guan
The 2019 ANCOLD seismic guidelines state that “A hazard assessment should be conducted for earthquake magnitudes Mw 5 and above. However, under certain circumstances, smaller magnitude earthquakes may form the lower limit. With masonry dams, slab and buttress dams, older concrete dams, and structural concrete components of dams, Mw 4 earthquake magnitudes should form the lower limit.” However, when using probabilistic Uniform Hazard Spectra (UHS) with Mmin less than 5.0 per the 2019 ANCOLD Guidelines, the hazard will be overestimated unless Conditional Mean Spectra (CMS) are used to represent the ground motions. As described by Somerville et al. (2015), use of the UHS can significantly overestimate the seismic hazard levels presented by individual earthquake scenarios because the UHS envelopes the ground motions from multiple earthquake scenarios in one spectrum. This overestimation is especially true of the ground motions from small magnitude earthquake scenarios. The probabilistic UHS may have large short period ground motions with contributions from a range of scenario earthquakes, but if the UHS is used as the design spectrum, these ground motions will often be represented by earthquake scenarios having inappropriately large magnitudes, long durations, and high long period ground motion levels. As a result, these design ground motions have the potential to overestimate the response of the structure under consideration. By using CMS spectra and time histories, the large probabilistic peak accelerations, predominantly from small earthquakes, are better represented by earthquakes having appropriately small magnitudes, short durations, and lower long period ground motion levels, yielding more realistic estimates of the response of the structure.
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2020 Papers
2020 – Implications of NSW Dams Safety Regulation 2019 on dam safety risk management
Learn moreMark Pearse, John Pisaniello, Sam Banzi, Peter Hill
A completely new dam safety regulation framework was introduced into NSW in November 2019. The new framework addresses all aspects of dam safety management. The implications for dam owners in respect of risk reduction measures (RRMs) that will need to be undertaken have been the matter of debate and are the focus of this paper. The Dams Safety Regulation 2019 requires that dam owners eliminate or reduce the risk posed by their dams but “only so far as is reasonably practicable” (SFAIRP). This is a change from the previous Dams Safety Committee requirement that risks should be reduced as low as reasonably practicable (ALARP). The previous guidance around the extent and timing of risk reduction has been removed and dam owners are now required to determine what is ‘reasonably practicable’. These changes were anticipated to save hundreds of millions of dollars from the reduced cost of risk reduction measures across the state of NSW. These savings appear unlikely to materialise given that dam owners are likely to be highly cognisant of the need to meet the common law expectation that RRMs should be implemented unless the costs associated with the RRMs are grossly disproportionate to the benefits gained. The key changes in the new regulatory framework are identified along with the legal and financial implications in regard to RRMs followed by next steps that should be considered by dam owners in NSW. Many of the implications are applicable to other dam owners who operate under common law (including all states of Australia and New Zealand).
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