Scour is a major threat to bridge safety. Bridge failures cost millions of dollars each year as a result of not only the direct costs of replacing and restoring bridges but also the indirect costs related to the disruption of transportation facilities. Instruments for bridge scour monitoring are necessary to study scour process and support bridge management. Lack of robust and economical scour monitoring devices prevents the implementationof bridge scour monitoring program among bridge owners. In this study, a new Time Domain Reflectometry (TDR) sensor has been developed for scour monitoring. This new sensor is designed using the coating technique. As a result, the new sensor is more resistant to corrosion and has a large rangeof sensing depth compared to previous uncoated metal rod sensors. The newsensor was evaluated by numerical simulations and laboratory tests. Sampling area and spatial weighting of the sensor were analyzed based on the developed numerical simulation approach via finite element software. Results show that coating can effectively reduce energy loss thus increase the sensing length. Laboratory results show that this sensor is accurate and reliable and suitable for scour monitoring. An algorithm has been proposed to automatic interpret signals acquired by this new sensor. This sensor is inexpensive and easy to install in geotechnical boreholes.
Abstract