Study on Local Scouring Monitoring of Hangzhou Bay Bridge

Hangzhou Bay Bridge is a crossing-sea bridge that spans the Hangzhou Bay of China, which has a total length of 36 kilometers and is the fourth longest crossing-sea bridge in the world. Hangzhou Bay has strong tides and large tidal range, the suspended sediment and bed material have the same particle size, the seabed sediment are complex and changeable, the development of the seabed groove changes rapidly. So local scour of the piles becomes a potential danger for the safe operation of the bridge. The pile of crossing-sea bridge lie in a complex three-dimension flow, and local scour could cause instability of substructure up to whole bridge failures. Facing scour risk, the bridge scour monitoring system is present and set out to deployfor effectively assessment scour risk of piles.. Besides preventing the risks of catastrophic failures, real-time field scour data can also be used to calibrate and refine the existing bridge scour simulation models. This study carried out local scouring monitoring on the sea platform area of the Hangzhou Bay Bridge. Based on the monitoring results, a formula for calculating the local scouring depth of pile under the action of bidirectional flow in Hangzhou Bay was proposed analyzed. At the same time, the evolution of scour holes in offshore platforms are introduced. A real-time bridge scour monitoring system based on fiber Bragg grating (FBG) is proposed based on the study of erosion mechanism. The monitoring system can directly obtain the changes of external pressure, displacement and other parameters. It has the advantages of strong antiinterference ability and high accuracy.