Research And Realization Of Oblique Mercator Projection In High-speed Railway Control Network

High-speed railway,as the core strategy of China’s infrastructure development,has played a huge role in China’s economic development.In order to ensure the safe operation of high-speed railway,it is necessary to ensure the accuracy of high-speed railway control network when constructing high-speed railway.The precision of high-speed railway control network is closely related to the map projection.At present,most of the railway construction projects in our country are based on Gauss projection control network.Its advantage lies in the effective control of projecting deformation,even in the case of most zoning Can meet the requirements of high-speed railway engineering measurement specifications.However,for the relatively large span of things(such as Shanghai and Kunming high-speed rail)linear engineering need to divide multiple projection,the establishment of a number of independent coordinate system to meet the needs of the coordinates of the construction of convergence,and adjacent areas between the conversion is also Trouble,to the actual construction of many inconvenience.Therefore,for the high-speed railway with east-west direction,this paper adopts the oblique-ray ink carton projection which can reduce the projection sub-band and effectively control the length of the projection deformation,and compare with the Gaussian projection method to verify the oblique Mercator projection The Practical Value of East-West to Railway Application.For the high-speed railway control network,the current use of "high-speed railway engineering measurement specification" TB10601-2009 clearly pointed out: high-speed railway line design surface height of the projection length of the deformation value can not be greater than 10 mm / Km [1],and The coordinate of the engineering plane must adopt the engineering independent coordinate system.There are two main errors in the projection deformation of Gaussian projection: one is the length of the elevation of naturalization correction;the second is the projection deformation correction.In this paper,the theory and method of the oblique Mercator projection are analyzed by using the data of the actual high-speed railway GPS control network under the influence of the two aspects of error,and the results of the Gauss projection are compared to prove the oblique ink The feasibility of the projection method,and through the design of oblique Mercator projection calculation software to quickly and easily calculate the results.The main contents of this paper are as follows: 1.The basic theory of Gauss projection and the deformation of Gaussian projection are described.2.Introduce the theoretical process of oblique Mercator projection-first establish the regional ellipsoid,and then convert the ellipsoid element to the sphere,again using the spherical polar coordinates to convert the oblique axis to the spherical earth coordinates,and finally converted to the oblique axis Mercator projection plane coordinates.3.The use of spherical coordinates of the use of the design of the MATLAB program to determine the best new pole and projection center line 4.to engineering example data as an example,using oblique Mercator projection method to calculate and analyze the results,and the current widely used Gauss projection method to compare the results obtained 5.the oblique Mercator projection method based on the theory,using MATLAB to determine the best new pole and projection center line to Visual C # as the development platform,prepared based on Gauss projection and oblique Axis ink Cato projection of high-speed rail control network data processing software,and with three examples to prove the use of optimized after the oblique axis Mercator projection accuracy is more stable.