因铁路工程分阶段勘测设计,周期长、方案变化频繁,控制点标石规格大、费用高.为节省成本,采用两期建网方式实施,先以低精度、低密度方式建立基础控制网用于勘测设计,后期按规范要求精度等级建立精测网用于施工.两期网成果存在差异,造成精测网与设计文件不匹配、与既有工程不匹配,给后续施工带来影响.为解决这一问题,在总结实践工程经验的基础上,提出接轨处测量一次到位,既有控制点移设,勘测留点精测网时联测,按施工精度、基于精测网进行既有构筑物测量方法等措施,实现成果差异最小化,并对既有工程匹配测量方法进行探讨,为相关规范修订精测网建立时机提供参考.
Due to the phased survey and design of railway engineering,the cycle is long,the scheme changes frequently,and the control point markers have large specifications and high costs.To save costs,a two-stage network construction method is a-dopted.Firstly,a basic control network is established in a low precision and low density manner for survey and design,and lat-er,a precision survey network is established according to the required accuracy level in the specifications for construction.There are differences in the results of the two phases of the network,resulting in a mismatch between the precision measurement network and the design documents,as well as a mismatch with existing projects,which will have an impact on subsequent con-struction.To solve this problem,based on the summary of practical engineering experience,measures are proposed to measure the connection point in one go,move existing control points,conduct joint measurement during the survey and reservation of precise measurement network,and minimize the difference in results based on construction accuracy and precise measurement network for existing structures.The matching measurement methods for existing projects are also discussed,providing reference for the establishment of precise measurement network in relevant regulations revision.