Research Of Coordinate System Selection And Control Points Stability Annlysis During The High-speed Railway Survey

As an important symbol of modernization to judge a country,high-speed railway has become the trend of the development of the railway,at home and abroad. With several speed upgrade,our country has entered the era of high-speed railway now. Compared with the traditional railway, the competitiveness of the high-speed railway including high speed,high density,high comfort and high safety,so high accuracy of measurement results are needed in the high-speed rail construction process. Different from traditional railway measurements,high-speed railway measurements belong to the category of precise engineering survey. The precise requirement of the smoothness railway orbits is very high,and the construction moulding survey accuracy must achieve millimeter level.In order to realize this goal, such as the selection of the coordinate system and the analysis of the stability of the control points, is a basic work for the key in the construction of high-speed railway. In addition to some special requirements of underline engineering and track construction,such as the the selection of the coordinate system and the analysis of the stability of the control points, are the basic work of high-speed railway construction.The system of coordinate length of deformation should not be greater than 10mm/km.This paper has analyzed using three different kinds of Gauss projection in establishing independent coordinate system in detail. Certainly,the control area and some problems existing in the high-speed railway measurement have been discussed at the seam time.Aiming at the “Fore corss” or the simlar east-west planning line of high-speed railway in our country,this paper presents a new idea of adopting the dual-standard latitude Lambert ortho-conic projectionin in the control survey of east-west high-speed railway engineering.Using ZhengXi high-speed railway as an example,and I have given the contrast analysis of the projection deformation ratio of them under the same conditions by calculating.The results showing that the dual-standard latitude Lambert ortho-conic projectionin is an feasible and efficient mothod in the establishment of the independent coordinate system.It also gives the steps to establish the coordinate system together using Gauss projection and dual-standard latitude Lambert ortho-conic projectionin.This article analyzes the optimized design and data process of GPS control network in HeFu high-speed railway Ⅷ CPI accurate survey network. To ensure objectivity and rigor of the control points’ stability analysis in CPI control network,this article take checkpoint method and scale parameter method to do compatibility test for three start points, and make comparsion for the 3D adjustment baseline values and design baseline values of three start points.The test show that:the three constraint adjustment start points in this resurvey are stable and reliable.This paper calculates the coordinates change before and after remeasurement,the relative precision of the coordinates difference between adjacent points, the RMSE and difference between two phases in HeFu high-speed railway Ⅷ CPI accurate survey network,then make stability analysis for remeasurement points in survey area through these three methods.The result show that:The program that combine the above three methods to make stability analysis for remeasurement control points is reasonable and reliable,it can provide an effecive analysis and detection method for similar projects.The stability of CPI remeasurement control points was analyzed that based on the twice coordinates’ displacement and the limit error of measurement,and the stability will be summarized into three classes of stable, basically stable and unstable. In order to maintain the consistency of all measurement results, basically stable and unstable points should be measured again,if the tolerance requirements are met through the comparison of the twice remeasurement data,then the first remeasurement results will be used. The stable point still adopt the original coordinate from design units.