Research On Bridge Deformation Monitoring Technology Based On PS-InSAR

The health monitoring assignment of in-service bridges in our country is increasing gradually.The current monitoring methods are mainly based on manual periodic inspection and bridge health monitoring system.But the traditional method of manual periodic inspection requires a long time and the closure of road and bridge.The health monitoring and safety evaluation system of large bridges is also complex and high cost.PS-InSAR technology can achieve millimeter deformation monitoring.Bridge deformation monitoring based on PS-InSAR technology will have wide range,all day,all-weather,reliable and economic characteristics.The advantages of this technology are especially important for small and medium sized bridges,which account for more than 90%of the total number of bridges.But the PS-InSAR technology is applied to the bridge deformation monitoring,the variable loads,such as traffic flow and temperature,will affect the deformation monitoring results of PS-InSAR.In this paper,after setting the artificial PS(Persistent Scatter)points in the Bridge Deformation Key Points,the deformation information of target bridge is acquired by technology of PS-InSAR.The paper collected the measured bridge temperature and traffic information at the beginning of June 2016 to the end of August,and established the statistical regularity of variable load(temperature and flow,etc.)of bridges under different weather patterns.Based on the above statistics,the random deformation of temperature and traffic flow is calculated by Finite Element Method under the satellite shooting time,so we can establish the random deformation time and space matrix of bridge deformation key points.Then,the random deformation in the PS-InSAR deformation information is eliminated by using the random deformation time and space matrix.Finally,the bridge safety warning system based on PS-InSAR technology is preliminary established with the permanent deformation.The conculusions is listed below:(1)The artificial PS points are set up on the Bridge Deformation Key Points,which can be used to link the PS-InSAR technology with the bridge engineering by Finite Element Method.(2)If the measured data of the bridge is lacked,we also can predict the temperature of the target bridge based on the statistical law of the temperature difference.The random deformation of bridge deformation key points under random traffic flow are within the range of mm,which is far less than the influence of temperature load(within the range of cm).(3)The results of PS-InSAR are in good agreement with the calculated bridge temperature deformation law of FEM.By comparing PS-InSAR results with FEM results,some conclusions can be yielded:? There is asymmetric settlement on both sides of the approach bridge(the northwest approach is larger).? The FEM results show that,at the pier and tower will be deformed upward(caused by temperature effect),but the PS-InSAR results show that deformation of pier and tower is down.This difference is result of geological,water level rise,structural damage,temperature effect and other factors.(4)Dongting Lake bridge is still in a safe state based on PS-InSAR technology security warning,which can be used normally.