Smart Rock Technology for Real-time Monitoring of Bridge Scour and Riprap Effectiveness -Design Guidelines and Visualization Tools

Based on the recently-completed proof-of-concept study, smart rock technology is a promising solution for bridge scour monitoring in real time. This project is an extended phase of study towards the implementation of the proposed passive smart rock technology. It is aimed to (a) characterize the movement of smart rocks and develop their design guidelines, (b) package, prototype, and deploy passive smart rocks at three bridge sites, and (c) document the field performance and display the spatial distribution of smart rocks around each bridge site. Its scope of work includes, but is not limited to, the following main tasks: (1) Incipient movement simulation and design of smart rocks (shape, size, and density) based on bridge and river geometries, riverbed material strengths, and flow conditions using empirical equations and laboratory hydraulic studies; (2) Prototyping of passive smart rocks with embedded magnets; (3) Long-term periodical measurements in normal operations and short-term continuous measurements during a severe flood event, and their comparison with a competing scour monitoring technology using ground penetrating radar; (4) Time-variant mapping of smart rocks on a Geospatial Information System (GIS); and (5) Platform and its application demonstration in supporting the design and maintenance of bridges by transportation agencies and consulting firms. Approximately 60% of bridge collapses in the United States (U.S.) are due to hydraulic effects. For example, scour around a bridge pier or abutment could make the bridge collapse in hours or days. To protect properties and save lives during a severe flood event, the scour process of affected bridges in a transportation network must be monitored, assessed, and responded in real time. The current practice in bridge maintenance is to visually inspect bridge foundation scour by divers every other year. This practice is both uneconomical when a bridge is in good condition and probable missing occurrence of bridge scour in between two inspections. Foundation scour has also been monitored with instruments mainly in normal operations of bridges. Due to erosion and refilling during severe floods, neither visual inspection nor existing instrumentation provides the actual maximum scour depth. Passive smart rocks made of concrete encasements were demonstrated to be cost effective for scour monitoring through laboratory and limited field tests. The concrete encasements are "smart" in two senses: (a) when properly designed, they automatically roll to the bottom of a scour hole; and (b) when remotely measured, they as field "agents" can provide the maximum scour depth as scour develops in the riverbed. During a severe flood event, the critical scour data can be transmitted to the engineer-in-charge or decision makers in real time. Smart rocks can also be used to evaluate in real time the effectiveness of a rip-rap scour countermeasure since incipient motion of rocks is indicative of the upcoming failure of a rock countermeasure. Passive smart rocks with one embedded magnet each provide the combined magnetic field intensity of the magnets group and the Earth by a remote magnetometer. Two rock localization algorithms were proposed with known and unknown magnet orientations. Critical to the localization of smart rocks by triangulation, the intensity-distance relation of a passive smart rock was significantly affected by the polarization of the embedded magnet. This influence can be effectively removed from a unique mechanism design that makes the magnet always oriented with the ambient magnetic field. To achieve a rock localization accuracy of less than 0.5 m, a measurement distance of over 20 m can be achieved in field conditions. In multiple laboratory tests, 2 cm accuracy has been repeatedly achieved for a scour depth of 18 cm with a small-scale pier model. It is practically impossible to separate the effects of individual magnets in a group unless one rock moves at any time. The magnetometer can be set up for field measurement in less than 10 minutes. Each smart rock deployed at bridge sites costs approximately $300. The trial-and-error design of smart rocks was proven effective during the August 7, 2013, flood event with a return period of over 100 years in Rolla, MO. The smart rock deployed at the US63 Gasconade River Bridge on September 24, 2012, and retrieved on October 4, 2013, moved downstream approximately 1 m in a scour hole near the bridge foundation. It was in a good condition and remained functional for magnetic field measurement. The so-designed smart rocks were also demonstrated to consistently roll to the deepest area of scour with multiple laboratory tests. However, the size and density of concrete encasements have never been optimized. The deliverables of this study include next generation prototype smart rocks, rock positioning and scour depth evaluation algorithms, time-variant mapping tools of spatially distributed smart rocks, and field performance data sheets of smart rocks. The movement characteristics of smart rocks, the periodic performance of smart rocks in normal operations (durability and waterproofing), and the real-time performance of smart rocks during a severe flood event (rock movement and detectability, scour depth estimation accuracy, and remote retrieval of maximum scour depth) are summarized in a final report. The outcomes and deliverables of this study can revolutionize current bridge scour management systems in terms of our ability to predict the process of bridge scour in real time. The smart rock technology collects only mission-critical data and relates the data to the rating of existing bridges based on foundation susceptibility to scour. It can potentially address the #1 cause of over 1,500 catastrophic bridge failures in the U.S. and provide a cost-effective solution to deal with bridge scour monitoring and mitigation issues.


  • English


  • Status: Active
  • Contract Numbers:


    MS&T 00048069

  • Sponsor Organizations:

    Department of Transportation

    Office of the Assistant Secretary for Research and Technology
    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Singh, Caesar

  • Performing Organizations:

    Missouri University of Science and Technology, Rolla

    328 Butler-Carlton Hall
    1401 N. Pine Street
    Rolla, MO  United States  65401
  • Principal Investigators:

    Chen, Genda

  • Start Date: 20140929
  • Expected Completion Date: 0
  • Actual Completion Date: 20160928
  • Source Data: RiP Project 39444

Subject/Index Terms

Filing Info

  • Accession Number: 01561170
  • Record Type: Research project
  • Source Agency: Missouri University of Science and Technology, Rolla
  • Contract Numbers: OASRTRS-14-H-MST, MS&T 00048069
  • Files: RiP
  • Created Date: Apr 25 2015 1:00AM