Establishing a high-speed railway long-distance tunnel independent control network according to “one point and one direction” will often produce lateral deviation and long and short chains in the joint section. It is necessary to take technical measures such as control network rotation or long and short chain to solve. Combined with the case of a network of independent control network for a long-distance tunnel of a high-speed railway in China, based on the results of the original reference ellipsoid and line control points, the central meridian (L 0) of the tunnel project center with the longitude of the tunnel is plotted, and the average tunnel elevation of the tunnel is Projection earth height (H 0), coordinate transformation calculation and relative stability and reliability analysis of existing line plane control points; select one stable control point of tunnel entrance and exit as starting point, in new projection parameters (L0 Under H0), the overall adjustment is carried out to establish an independent control network for the long tunnel. The results show:
(1) The tunnel independent control network established by the method has high precision and uniform error, which can meet the requirements of network construction precision and improve the tunnel penetration accuracy;
(2) “One point one direction” Compared with this method, the joint segment control point (S = 9.1 km) with the same baseline file, starting point and projection parameters, the maximum coordinate difference Δx is -63.4 mm, Δy is 85.3 mm, requiring technical processing;
(3) The method can solve the problems of large lateral deviation and long and short chain of the connecting section, and ensure the smooth connection between the tunnel and the adjacent structure.