Wireless monitoring of scour and re-deposited sediment evolution at bridge foundations based on soil electromagnetic properties

Abstract

This version is available at https://strathprints.strath.ac.uk/54048/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Abstract:Hydraulic structures constitute the most vulnerable elements of transportation infrastructure.Recent increases in precipitation have resulted in severe and more frequent flash flooding incidents. This has put bridges over waterways at higher risk of failure due to scour. This study presents a new sensor for measuring scour depth variation and sediment deposition processes in the vicinity of the foundations to underpin systems for early warning of impending structural failure. The monitoring system consists of a probe with integrated electromagnetic sensors designed to detect changes in the dielectric permittivity of the surrounding bridge foundation.The probe is equipped with a wireless interface and was evaluated to assess its ability to detect scour and sediment deposition in various soil types and under temperature and water salinity conditions that would commonly occur in a practical installation environment. A novel methodology is also developed enabling discrimination between in-situ and re-deposited sediment delivering vital information about the load bearing capacity of the foundation. The experimental approach was validated using 'static' scour simulations and real-time open channel flume experiments. Results indicate that the sensor is highly sensitive to underwater bed level variations and can provide an economical and accurate structural health monitoring alternative to existing instruments.

Electromagnetic Sensors for Underwater Scour Monitoring

“…(1) Pulse or radar devices [16][17][18] High Medium (2) Single-use or float-out devices [19] Low Medium (3) Fiber-Bragg grating systems [20,21] Low Low (4) Sounding or driven rod systems [19,22,23] Medium Medium (5) Sound wave devices [24][25][26] High High (6) Electrical conductivity devices [27] High Medium (7) Dielectric probes [28] High Medium Indirect Scour Measurement Devices (8) Tilt sensors [19,24] Low (9) Accelerometers [26,[29][30][31] Low (10) GPS [32,33] Medium (11) Satellite [34,35] Low…”

“…The dielectric permittivity can therefore be measured if a calibration function is established to convert the resonant frequency read by the sensors into a permittivity value, which differs between the soil in the riverbed and the water [28]. The system is calibrated to detect erosion and deposition of riverbed sediment in different soil types and under temperature that would commonly occur in a real case-study scenario [28]. It also allows for distinction between in situ and redeposited bed material, providing useful information about the load-bearing capacity of bridge foundations.…”

“…It also allows for distinction between in situ and redeposited bed material, providing useful information about the load-bearing capacity of bridge foundations. It is noteworthy that, although smart sensing bars with electromagnetic devices have already been proposed and studied [28], to the authors' knowledge, this is the first time they have been applied to a real case study for the continuous monitoring of scour at a bridge location. The dielectric permittivity can therefore be measured if a calibration function is established to convert the resonant frequency read by the sensors into a permittivity value, which differs between the soil in the riverbed and the water [28].…”

“…It is noteworthy that, although smart sensing bars with electromagnetic devices have already been proposed and studied [28], to the authors' knowledge, this is the first time they have been applied to a real case study for the continuous monitoring of scour at a bridge location. The dielectric permittivity can therefore be measured if a calibration function is established to convert the resonant frequency read by the sensors into a permittivity value, which differs between the soil in the riverbed and the water [28]. The system is calibrated to detect erosion and deposition of riverbed sediment in different soil types and under temperature that would commonly occur in a real case-study scenario [28].…”

BRIDGE SMS: Intelligent bridge maintenance and management system

“…One of the main disadvantages of current standards and inspection practices is that, in general, they do not reveal actual riverbed level variations around the foundations of structures due to several issues associated mainly with the actual procedure and frequency of inspections (Michalis et al, 2015). Even though water and flow characteristics around bridge piers have been thoroughly investigated both experimentally and numerically, there is still a lack of a tool that can offer fast and reliable predictions (Valyrakis et al, 2015).…”