“5.12”汶川大地震发生后,地震灾区内的国家高等级控制点被破坏殆尽,并且灾区余震、泥石流不断,传统的依赖地面标石维持基准的方式不具可行性。为了满足蓝家岩特长隧道勘测和施工的需要,采用GPS定位技术、大地水准面精化技术建立了隧道测量基准。 After the May 12 earthquake in Wenchuan, the high-level national control points in the quake-stricken area were destroyed and the aftershocks and mudslides continued in the quake-hit areas. The traditional way of relying on the surface dredging stone to maintain the benchmark was not feasible. In order to meet the needs of the Lanjiayan extra long tunnel for surveying and construction, the GPS tunneling technique and the geoid refining technique were used to establish the tunneling datum.