Study On The Application Of Dam Deformation Monitoring At Hydropower Station Using GPS Technique

There are abundant hydropower resources in our country. Up to now, more than 25,800 hydropower stations have been constructed. To ensure the safety of dams, it is very important to provide precise deformation and healthy monitoring. This paper presents the purposes, requirements, and methods that are used in dam monitoring, and concludes the problems that may occur in the applications, such as high expenses, poor observation condition, influence of water atomization, different classifications of network, lack of real-timing & synchronizing, etc.GPS(Global Positioning System) has a lot of advantages, e.g. high accuracy, high reliability, high efficiency, and automatic operation. With the development of GPS technology, it has been applied to deformation monitoring of dams for years. However, most hydropower stations are built in mountains and valleys area, say the West of China, the approach of applying GPS technique to the dam health monitoring has been restricted by the blocking of GPS signal. This paper focuses on the influence sources of GPS surveying in the field, and summarizes the key factors and the requirements of GPS application on dam deformation monitoring.A simulated experiment is conducted to study on the high precise GPS displacement monitoring in horizontal directions, which has proved the possibility of applying GPS technology to dam deformation monitoring, and finds out the methods and conditions for the field application. The conditions of this simulation study are obtained by the author through base ordering, instrument checking, experiment designing, software studying, and then observation data are collected and analyzed. The author analyzed the precision of GPS baseline, spot coordinates, and external conditions via parameter comparison, finally concluded the best parameters of GPS application on the deformation monitoring, such as elevation cut-off, length of observation session, best observation period, the number and distribution of datum marks, coordinates accuracy of datum mark, troposphere parameter estimation, analyzing software and orbit ephemeris.As an example, the Zipingpu Hydropower Station's monitoring network is studied. The paper does a comparison experiment on high precise GPS surveying, introduces the conditions of traditional triangulate net and the procedures comparedwith GPS surveying. Through comparing and analyzing slant length and coordinate of traditional triangulateration net, it has been proved to be possible to apply GPS to high precise deformation monitoring.The research shows that it's possible to apply GPS technology to dam horizontal displacement monitoring, in the case of using proper condition and method, following the precise requirements of regulation, as well as the best choice of parameters on GPS data processing for the dam deformation monitoring. Some useful results are obtained, which will be very helpful and of guidance for practical applications.Finally, the advantages of applying GPS to dam deformation monitoring are summarized, and some useful proposals for further investigation and study are given.