Research On The Methods And Systems For Monitoring Tunnel Anchorage Structure Displacement

After the impoundment of the three gorges reservoir area,complex water erosion environment,make the stress and shape of the anchorage change.Anchorage of suspension is one of the main bearing structure of bridges,once the anchorage structure is damage,it not only will pose a threat to self-security of anchorage system,but also harm stability of the whole bridge structure and result in loss of life and property.Therefore,it is urgent to develop methods and systems that assess the situation of anchorage structure displacement.The paper combine the science and technology research plan projects of Chongqing: the key technology research and demonstration of suspension Bridges anchorage system safety monitoring,evaluation and early warning;and research the anchorage structure,bridge monitoring system,the anchorage of displacement monitoring method and so on at home and abroad.On this basis,four anchorage structure displacement-monitoring methods and systems are designed,which are outlined below.(1)Anchorage structure of displacement monitoring method and system based on point laser image.The system sets up corresponding relationship of the surface and the like by pixel calibration,obtain the real-time variation of the laser spot by the use of laser spot center detecting algorithm,compute the displacement of anchorage structure by the given formula of displacement.Improving the monitoring performance of the system by the error correction model.The experimental results show that the laser spot center detecting calculation error is 1.75%.When the displacement of anchorage structure is between 0 mm and 25 mm,the system measurement precision can reach 0.1 mm,measurement error can be controlled within 2.16%.Establish a linear regression equation by application of least squares method,and estimate the equation expression,goodness-of-fit R2 is 90.29%,showing the effect is better.At present,the system has been successfully applied in two kinds of the actual bridge health monitoring.(2)Anchorage structure displacement monitoring method and system based on line laser projection.Put forward improvement for system based on the analysis of the system error sources.The system can simultaneously measure the anchorage face and strand displacement,and can eliminate device error of collimating laser emitter and reverse video acquisition.It is a detection algorithm based on dynamic difference of light center,it can monitor laser speckle image in real-time through the way of the difference image acquisition,dynamic extraction,image filtering,image correction,spot center detecting.Apply self-writing software to analyze and process information obtained finally,and get the actual displacement of anchorage structure.The research results show that when the measurement range is between-100 mm and +100mm,video acquisition device resolution is 1920×1080 pixels,the accuracy of measurement can be easily reached 0.1 mm.Compared the method with the laser image monitoring method proposed in front of the content,the results show that the two methods are consistent.(3)Anchorage structure of displacement monitoring method and system based on hydraulic type.The system can be real-time and accurate monitoring of anchorage structure change without having to calculate liquid density and gravitational acceleration,and keep a constant liquid level height at the same time.The paper puts forward a kind of anchor span strands of displacement and strain measurement method for the relationship between anchor span strand tension and displacement of anchorage.Set the stage for further analysis of the anchoring system overall performance.(4)Anchorage structure of displacement monitoring system based on MEMS.The system establish the corresponding relationship between angle and the voltage value by the three axle load force acceleration sensor ADXL335,and combine with the algorithm of cubic spline interpolation and zero point floating,and realizes the tilt displacement measurement.The experimental results verify the reliability of the system.To sum up,the thesis addresses the design of four novel methods and systems of anchorage structure displacement monitoring,which are important significance to the anchorage comprehensive evaluation and early warning.