Monitoring Bridge Scour Using Fiber Optic Sensors.

摘要

The scouring process excavates and carries away materials from the bed and banks of streams, and from around the piers and abutments of bridges. Scour undermines bridges and may cause bridge failures due to structural instability. In the last 30 years, more than 1,000 bridges collapsed in the US and about 60% of the failures are related to the scour of bridge foundations. Due to the difficulty in inspecting bridge scour, scourinduced failures tend to occur suddenly without prior warning or signs of distress to the structures. Owing to the threat of hurricane-induced flooding and the fact that there are a significant number of coastal and river/bayou bridges in Louisiana, a more reliable inspection and monitoring procedure for bridge scour is needed. This proposed study is to develop bridge scour monitoring techniques using fiber optic sensors. Based on theoretical and numerical studies, a few mechanisms were proposed for foundation scour monitoring and verified in laboratory tests. In order to apply those mechanisms to field bridges, three instrumentation were designed and tested, and one design was selected for field applications. According to the selected design, two 18-ft long piles with Fiber Bragg Grating (FBG) sensors were then fabricated, transported, and installed besides the foundation of the field bridge. Finally, the long-term monitoring was conducted to evaluate the foundation scour condition.