Processing And Analysis Of Bridge Deformation Monitoring Data Based On Gps Surveying

With the booming development of national economy and transportation, more and more large-span bridges emerge as the times require. Security problems of bridge structures in the operation process attract great attention of people due to the complexity and importance of bridge structures. The frequent bridge accidents at home and abroad made it is particularly important to carry out necessary deformation monitoring to bridges. So deformation monitoring of large-span bridges becomes hot field in civil engineering sector for people to pay close attention and research. Traditional monitoring methods have their advantages and disadvantages and the corresponding application conditions. Compared to other methods, GPS as one of the latest monitoring tools used for bridge deformation monitoring has many advantages, such as all weather, high degree of automation, real-time monitoring and so on. Of course, in the course of actual deformation monitoring we combine GPS monitoring technology with traditional monitoring methods to grasp the characteristics and safety of bridges better. GPS deformation monitoring is given the time-related data series, usually containing both the real bridge deformation signals and the signal error namely the noise. Therefore, it is necessary to do noise reduction on the observation data in order to extract the true signal characteristics. This paper carried out research in the following areas:1,There are a lot of methods to process the GPS observation data in order to extract the true signal characteristics. In this paper wavelet analysis as a time-frequency localization analysis method is used to do data noise reduction processing. First the paper analyzes the development from Fourier transform to the wavelet analysis, also introduces multi-resolution characteristics of wavelet transform and several commonly used wavelet function in order to master the theoretical basis for the following application.2,Combining the actual situation of Yangtze River bridge, the paper discusses the design and implementation process of GPS deformation monitoring system, including the layout of benchmark point and monitoring points, the selection of GPS receiver and antenna, the algorithms of system post-processing software, communication network architecture, and so on.3,The paper discusses the selection criteria of wavelet decomposition levels, wavelet functions, threshold strategies and the quantify functions. Then this paper introduces wavelet de-noise processing to GPS observation data using threshold de-noising method with different decomposition levels, wavelet functions, threshold strategies and quantify functions. The results indicate that the satisfied noise reduction effectiveness is obtained with db6 wavelet function and heursure threshold strategy under the soft threshold quantization rather than others. It has a certain reference value for the actual project monitoring data noise reduction.4,Based on the real deformation characteristics of the bridge, the paper compares GPS monitoring system data and the IBIS-S system data to verify the reliability of the GPS system data. According to GPS monitoring data, this paper analyses the deformation of the bridge in the process of operation and compares with the theoretical value. The results indicate that the distance and elevation difference between two towers measuring points are basically consistent with the actual, and deformation trend of upstream and downstream measuring points is highly consistent correlation. It can be seen that GPS monitoring system is running normally to ensure the safe operation of the bridge.5,Finally the author gives a summary of the text, and proposes some future research work prospects.