1, University of Strathclyde2
Introduction A key component of management of water resources lies in asset monitoring of the structures that contain water, e.g., dams and embankments. Earthworks failures can lead to disastrous consequences, including flooding, and can be very expensive to remediate. This paper presents a solution to assess the physical integrity of vulnerable earth structures (dams, embankments and cuttings) - thereby facilitating the shift from more costly responsive remediation of earthwork failures to early intervention. While current methods (including sophisticated automated procedures, sensors and SCADA systems) do provide some information regarding the health of the assets, they have a number of limitations: (1) the cost of deploying and maintaining these solutions; (2) the level of intrusiveness; (3) the need for experienced engineers validating measurements by visual inspection; (4) remoteness of many sites; and (5) low temporal resolution with limited scope for predictive approaches to asset failure.
Methodology Early intervention and prevention requires identification of the incremental development of internal conditions that ultimately trigger failure. The low cost of the devices allows deployments of higher density, increasing spatial resolution and monitoring in real-time. This, unlike conventional approaches, allows better representation the soil heterogeneity both spatially and temporarily. To this end, we will present observations from our trials of automated resistivity, movement and pressure measurements. The developed sensor nodes operate at low voltages, integrates a range of analogue and digital sensors, using a single interface for measuring resistivity, pressure, motion pore pressure, and temperature, can be developed in compact form (currently 32.5cm high with diameter 14.5cm for prototyping), are non-intrusive to their compact nature and continually log data with no human intervention. We will also discuss the design aspects of the casing so that our electronic sensor nodes are robust to harsh conditions, including extreme temperatures, moisture, high voltages, and wildlife, when buried. Data is stored on a data collection hub, and due to remoteness of these sites, remote communications has been enabled through near white-space frequencies to highlight potential risks to the appropriate stakeholders in real-time.
Results and conclusions This paper presents a unique, customized and cost-effective platform for automated monitoring of earthworks through prototyping a novel hardware/firmware solution in consultation with various stakeholders: (i) integration of analogue and digital sensors for measuring pressure and motion, (ii) resistivity board that is controlled by main board, (iii) variable and on-demand sampling rates that can be dynamically controlled, (iv) a prototype mechanical waterproof design for housing main board, resistivity board and relevant sensors. We show initial results for ground movement, pressure and resistivity. Resistivity results are as expected based on the literature for clay-type soil. We also observe noticeable ground movement variation with artificially induced disturbance. We conclude that it is possible, through trials at Scottish Canals assets at Falkirk Wheel, to accurately monitor multiple earthworks parameters simultaneously, continuously, in real-time and without human intervention, as well as communicate data remotely in real-time to enable prediction of the onset of earthworks failures.