Three-centered circle fitting method for inner contour of railway tunnel anchor section

The invention relates to a three-centered circle fitting method for the inner contour of a railway tunnel anchor section, which comprises the following steps of: establishing a Cartesian coordinate system formed based on a structure center line and a horizontal inner rail surface line, and determining the coordinates of key control points of the inner contour by adopting a multi-circle intersection plane equation set analysis mode according to the fitting principle from top to bottom and from left to right, and finally fitting the inner contours of the arch part, the side wall and the inverted arch of the anchor section of the catenary of the single-track railway tunnel. The method can be used for a three-centered circle fitting method for the inner contour of the 160 km/h single-track railway tunnel anchor section, a multi-circle intersection plane equation set analysis means is introduced, arc co-tangent transition and area optimization are achieved, a large amount of trial design work generated due to freq