Research On The Detection Methods For The Suspension Bridge’s Tunnel Anchorage Structure Displacement

Suspension bridge is one kind of the greatest common extra-large bridges. And its anchorage structure is the most important stress structure whose general stability and stress state directly affect the suspension bridges’ safety and normal service. Creep displacement of the anchorage structure directly reflects its stress condition; therefore, monitoring the anchorage’s creep displacement is significant to master its structure variation tendency.After impounding in Three Gorges Reservoir Regions, serious craze and deviation appeared in the anchorage chamber that is a part of the surrounding suspension bridges; water penetrated in the anchorage zone; corrosion happened on the surface of the anchor heads and splay saddles and so on. In order to insure the suspension bridges’ security, the critical anchorages’ creep displacement needs to carry out real-time monitoring. However, because the tunnel anchor chamber has specific requirements to geology, it is less used in practical engineering. And currently there are no related research papers and documents about the tunnel anchorage structure’s creep displacement.This paper had researched the related technologies, such as the domestic and foreign tiny displacement measurements, applications of tunnel anchorage structure, stability of surrounding rock, and so on. Then two kinds of devices and methods to measure the tunnel anchorage structure’s displacement are proposed; furthermore, consists of the two devices are developed out, and the corresponding methods and procedures are put forward. By set up the relevant simulative experimental platform, system performances such as accuracy, reliability and stability had been tested. Based on the practical suspension bridges(Zhongxian Yangtze River Bridge and Fengdu Yangtze River Bridge), one of the two methods was designed out and implemented in the above two bridges.Specific main research contents are as follows:1. Designed the anchorage structure displacement monitoring system based on the laser pictures’ analysis, introduced the system consists and measurement’s theory, proposed the system implement’s scenario on the basis of the above research, and theoretically analyzed the related technological documents in detail.2. Designed the anchorage structure displacement monitoring system based on the displacement difference value amplification, introduced the system consists including basic thoughts and detector’s structure, proposed the improved plan on the basis of the correction to the system error, and analyzed the measuring theory and characteristics of the improve plan.3. By constructing the simulative experimental platform to design and implement a series of tests aimed at the two systems respectively, and through setting the related experimental conditions, devices and procedures, each system was experimentally demonstrated and effective conclusions were achieved, so as to compare and analyze the systems’ properties.4. Conducted the anchorage structure displacement monitoring system based on the laser picture’s analysis in Zhongxian and Fengdu Yangtze River Suspension Bridges, proposed the improved plan aimed at the practical applications, analyzed the monitoring data and verified the system’s usability.Experiments illustrate that both of the two systems can reliability measure the tiny displacement. While the measuring range is from-20 mm to 20 mm, the anchorage structure displacement monitoring system based on the laser picture’s analysis could control the relative error in 10%. And while the inner diameter ratio of the picked up pipe is 1:5, the measuring error accuracy can reach to 0.1mm, in addition, the accuracy series will get higher with the inner diameter ratio getting greater. By analyzing the monitoring data of the anchorage structure displacement system based on the laser picture’s analysis, the result presents that the system could monitor the anchorage structure displacement in a long time and the measuring accuracy could achieve 0.1mm, and the system could work out the anchoring zone’s creep frequency, range, long-term tendency and other state data.