基于北斗的超长距离跨河高程测量技术研究与实践

Research and practice on ultra long distance cross river elevation measurement technology Based on BeiDou

目前常用的跨河高程测量方法有水准测量、测距三角高程测量、GNSS测量。常规水准测量视距较短,测距三角高程测量对场地条件要求非常高,要求测点间相互通视并同步对向观测,测量精度受风力、大气折光、距离远近影响较大,随着测量距离的增加,垂线偏差的影响也随之增大,导致精度降低。当跨距超过3500 m时,没有相关标准规范可以遵循,对于跨度10 km以上的超长距离跨河高程传递测量,更是一个较大的挑战。本文研究对超长距离跨江工程进行高程测量的方法。首先介绍基于北斗跨河水准测量方法的基本原理;然后以沪渝蓉高铁崇太过江隧道跨长江高程传递为例,阐述在跨河水准测量实施过程中水准控制网的布设方法、外业测量质量控制、数据处理及精度分析等。实践结果表明,在地势较平坦、高程异常变化率相对平缓的测区,通过布设强制观测墩、优化设计控制网网形、采用双测线跨河水准测量方法,内外符合精度指标均可满足二等水准测量要求。本文成功实现了10.2 km超长距离跨河水准测量技术在沪渝蓉高铁崇太过江隧道二等水准传递应用,对类似工程项目有很好的借鉴和参考意义。

At present,the frequently used methods for cross-river elevation measurement include leveling,ranging trigonometric elevation,and GNSS cross-river elevation measurement.Conventional leveling has a relatively short sight distance,and ranging trigonometric elevation measurement requires very high site conditions,requiring mutual visibility and synchronous alignment observation between measurement points.The measurement accuracy is greatly affected by wind,atmospheric refraction,and distance.As the measurement distance increases,the influence of vertical deviation also increases,and the accuracy of trigonometric leveling has decreased.When the span exceeds 3500 m,there is no relevant standard specification to follow,which is a considerable challenge for cross-river elevation transfer measurement with a span of more than 10 km.This paper studies the use of measurement method for elevation measurement of ultra-long-distance cross-river projects.The basic principle of BeiDou cross-river leveling method is firstly introduced in the paper,taking the elevation transmission of Chongming-Taicang river-crossing tunnel of Shanghai-Chongqing-Chengdu high-speed railway as an example,the layout scheme of leveling control network,field measurement quality control,data processing,and accuracy analysis are elaborated during the implementation of cross-river leveling measurement.The practical results show that:In the survey area with relatively flat terrain and relatively gentle change rate of elevation anomaly,the control network is optimized by laying compulsory observation pier,and the two-line cross-river leveling method is adopted.All the accuracy indexes attached inside and outside meet the requirements of second-order leveling.The 10.2 km ultra-long-distance cross-river leveling technology has been successfully applied to the second-class level transmission in Chongming-Taicang cross-river tunnel of Shanghai-Chongqing-Chengdu high-speed railway,which has very good reference significance for similar engineering projects.