在隧道未整体贯通的条件下，采用边掘进边在贯通段提前实施铺轨的施工方案时，为解决利用平导、无方位角附合条件下进行相向施工的无砟轨道难以准确对接的技术难题，提出洞内CPⅡ导线采用高精度陀螺仪加测方位边保障导线方向精度的方法。通过对2种坐标方位角的精度匹配与较差限差标准、隧道铺轨建筑限界匹配检查方法、高精度陀螺仪CPⅡ导线的闭合差法检查、横向偏差与建筑限界匹配优化检查等方面进行探讨，得出特长隧道CPⅡ陀螺导线的约束应用条件为: CPⅡ导线坐标方位角与陀螺坐标方位角精度相当，坐标方位角较差及导线全长相对闭合精度满足隧道二等限差要求，与隧道建筑限界的匹配应得到优化，且洞内CPⅡ中联测的施工控制导线点横向偏差要求在隧道施工净空裕量范围(5 cm)以内。按照陀螺方位边的约束应用标准，确定隧道洞内CPⅡ导线采用陀螺方位约束的计算方法。目前，隧道已经贯通，无砟轨道铺轨全部完成,各项指标满足施工验标要求，表明CPⅡ导线采用陀螺方位约束的方法可用于隧道工程实践。
When adopting a construction scheme consisting of
excavation followed by laying of tracks prior to tunnel breakthrough, there is
a technical problem with accurate docking of ballastless tracks through parallel
adit without an azimuthalclosure check condition.
Consequently, a method ensuring the directional accuracy of the CPⅡ traverse by measuring the azimuth with a highprecision gyroscope is proposed. By discussing the accuracy matching
and poor tolerance standards of the two azimuthal coordinates as well as
confirming the matching of tunneltracklaying construction clearance, checking the closure error of the
highprecision gyroscope, and optimizing the matching
between the lateral deviation and the construction clearance, the following
constraints for using a CPⅡ gyroscope in an extralong tunnel are obtained.(1) First, the accuracy of the CPⅡ traversecoordinate azimuth and gyroscopecoordinate azimuth is almost the same; (2) the closure error of the
coordinate azimuth and relativeclosure errors of the
extremelength traverse meet secondclass tolerance requirements for the tunnel; (3) matching of
gyroscope with the tunnelconstruction clearance should
be optimized; and (4) the lateral deviation of the constructioncontrol traverse points in CPⅡ should be
within 5 m of the tunnelconstructionclearance distance. According to the constraints for application of
gyroscope azimuth side, a method for the calculation of constrained gyroscope
azimuth is determined for CPⅡ traverse in the tunnel.
The results of this method show that every indicator complies with the
requirements of the inspection standards of construction. This indicates the
feasibility of the CPⅡ traversebased method for the constrained gyroscope azimuth in the tunnel.
