特长隧道洞内交叉导线旁折光定位定值探讨

Discussion on the Fixed Value of Lateral Refraction Positioning for Cross Conductors in Extra-long Tunnel

特长隧道洞内导线测量中,贴近隧道侧墙的视线易产生旁折光现象,为消除或削弱旁折光对特长隧道洞内导线水平角测量的影响,提高隧道洞内横向贯通精度,采用加测洞内交叉导线高精度横向超短边的方法,基于余弦定理反演受旁折光影响的小夹角值,并对反演的角度进行误差分析,以确定观测角度与反演角度较差的判别指标;并逐一将小夹角反演值与实测值进行比较,以实现对隧道洞内导线水平角显著性旁折光影响测站的定位和显著性旁折光大小的定值。研究结果表明,应用高精度全站仪自由测站方法可测得较高精度的超短边测量值,通过加测特长隧道洞内交叉导线高精度横向超短边,可反演得到较高精度的交叉导线小夹角值,实现对水平角观测显著性旁折光影响的定位定值,增加隧道洞内导线测量外业观测成果的检核条件,提高洞内导线的测量精度。

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 highprecision 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,highprecision 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.