Laboratory Investigation of Time-Domain Reflectometry System for Monitoring Bridge Scour

Bridge scour is a severe problem that costs millions of dollars of damage to infrastructure annually and causes occasional loss of life. Scour occurs during times of rapid river flow and can be increased by icing conditions when sediments, including rocks, gravel, and silt, are transported by the currents, undermining bridge pier and abutment foundations and other structures. Scour is dynamic; during a single high-flow event, scour may occur during rising stages and near the peak. Deposition of sediments into the scoured area may occur during falling stages and during low flow. The worst case and the net effect cannot be easily predicted. Monitoring scour is difficult, and existing instruments have limitations that prevent their use in some situations. A technique and system employing time-domain reflectometry can be used to constantly monitor the extent of scour around riverine structures. This system is capable of continuous round-the-clock operation and can indicate changes in sediment depth of less than 5 cm.