Field Application of Magnet-Based Smart Rock for Bridge Scour Monitoring


In this study, a smart rock, which is a magnet embedded in a concrete ball and whose direction is always pointing downwards, is proposed to monitor bridge scour depth. Based on the theory of magnetic field, the distribution of the magnet-induced magnetic field (MMF) induced by the smart rock was derived. An algorithm was developed to localize the position of the smart rock. Field tests were conducted at a bridge pier at three different times. Both the intensities of the ambient magnetic field (AMF) and the total magnetic field (TMF) were measured with a magnetometer. Results showed that the presence of steel reinforcement or steel girders in the bridge changed the distribution of the geomagnetic field. The algorithm successfully localized the position of the smart rock with an error ranging from 0.26 to 0.33 m, which satisfied the requirement for engineering applications. The effective monitoring range depends on the variation of the AMF, and the maximum monitoring depth ranged from 11.5 to 8.5 m as the standard deviation of the AMF increased from 32.3 to 80.75 nT.


Civil, Architectural and Environmental Engineering

Research Center/Lab(s)

INSPIRE - University Transportation Center


Financial support for this study was jointly provided by the Fundamental Research Funds for the Central Universities of China under DUT17RC(3)076 and the US Department of Transportation Office of the Assistant Secretary for Research and Technology under cooperative agreement OASRTRS-14-H-MST and by the Missouri Department of Transportation.

Keywords and Phrases

Bridge scour; Localization algorithm; Magnetic field; Non-contact measurement; Smart rock; Structural health monitoring

International Standard Serial Number (ISSN)

1084-0702; 1943-5592

Document Type

Article - Journal

Document Version


File Type





© 2019 American Society of Civil Engineers (ASCE), All rights reserved.

Publication Date

01 Apr 2019