The Research On Data Processing Of GPS Deformation Monitoring Network & Combined Adjustment

Because of high-efficient, high-precision, no distance limitation, all-weather operation, highly automated and so on, the technology of GPS positioning is used in the security monitoring of the dam. Through the study of the mathematical models of GPS dam deformation monitoring data processing, a station orthogonal coordinate system works as the reference coordinate system, that its coordinates origin is one point of three-dimension deformation monitoring network. Its relative Mathematical models and formulas have been successfully derived. Quasi-stable adjustment has successfully avoided the Projection deformation errors and the effect of the accuracy of known-points in the restricted adustment. Considering to the base points of quasi-stable adjustment, the special t testing has been used to detect quasi-stable points' displacement. The method only removes the largest-displaced point if there is t-testing data surpassing its limitation and it makes sure the correct decision. A dam deformation monitoring data-processing software has been developed. With the process of the third period data of a gabion dam data, the correct mathematical model and software has been proved through the quasi-stable pre-adjustment, raw error detecting and removing , quasi-stable adjustment, precision assessment, significant displacement checking. The method of improved data snooping can detct most of the raw error only in one testing and it makes data snooping more efficient. It has been derived that the mathematical model of three-dimension combined adjustment with GPS and other surveying data under station orthogonal coordinate system in deformation monitoring networks. In this model, seven observation values can be processed: GPS baseline vectors, slant distances, horizontal distances, horizontal directions, direction angles, Vertical angles, level elevation differences. The data processing model considers vertical deflection and vertical refraction errors and eliminates them through parameterized methods. Three models of the vertical refraction are given too. The reformed formula of Helmert square error has been derived and it simplifies the computing model and releases the processing work.