长大桥隧工程的GPS跨障碍高程控制

为解决长大桥隧工程GPS高程控制中障碍物两侧的高程基准不一致问题,提出了一种改进的GPS水准方法:首先由直接的函数拟合方法分别拟合障碍物两侧的似大地水准面,进而求得各自的地面垂线偏差;再根据天文水准原理,由两侧所求的垂线偏差计算跨障碍的高程异常差。根据以上思路进行研究,并以跨越31km海湾的杭州湾大桥进行试验,试验结果与二等几何水准比较,最大较差29mm,最小较差3mm,平均较差16mm,达到二等几何水准精度。

GPS height control survey across obstacle for long span bridge and tunnel

The key problem of GPS height control survey for long span bridge and tunnel is that the height datum on each side of the obstacle is not consistent.So the general GPS leveling method can not be used directly.A new method in this paper is offered to solve the question,which is based on astronomical leveling.First,the general GPS leveling method is used to fit local quasigeoid on each side of the obstacle separately and then surface deflection is determined.Afterwards,principle of astronomical leveling is adopted to compute height anomaly difference across obstacle.The new method based on the above thought is put to the test in the Hangzhou Bay Major Bridge which spans 31 km.The result of the test is compared with grade two leveling.The max difference is 29 mm,the minimum difference is 3 mm and the average difference is 16 mm.Accuracy of the new method reaches grade two leveling.