Discussion on the Fixed Value of Lateral Refraction Positioning for Cross Conductors in Extra-long Tunnel
In the measurement of cross conductors in extra-long tunnel,the line of sight close to the side walls of the tunnel will produce the phenomenon of lateral refraction.In order to eliminate or weaken the influence of lateral refraction on the horizontal angle measurement of cross conductors in extra long tunnels and improve the accuracy of transverse penetration in the tunnel,a high-precision transverse ultra short edge method for cross conductors in the tunnel was added.Based on the cosine theorem,the small angle value affected by lateral refraction was inverted,and the error analysis of the inverted angle was carried out to determine the discrimination index of the difference between the observation angle and the inverted angle.Inverted values of small angles with the measured values one by one were used to achieve the positioning of the measurement station for the significant lateral refraction of the horizontal angle of the tunnel conductor and the determination of the magnitude of the significant lateral refraction.The research results indicate that the application of high-precision total station free measurement station method can obtain high-precision ultra short edge measurement values.By adding high-precision transverse ultra short edges of cross conductors in extra-long tunnel,high-precision small angle values of cross conductors can be inverted,which could help achieve the positioning and determination of significant lateral refraction effects on horizontal angle observation,increase the verification conditions for field observation results of tunnel conductor measurement,and improve the measurement accuracy of tunnel conductors.
high-speed railwayextra-long tunneltraverse measurement inside the tunnelhorizontal ultra short edgehorizontal angle measurementside refraction
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