利用高精度GPS测量建立坝址区测绘基准的探讨

针对超长隧洞及大型水利工程测绘基准问题，提出了利用高精度GPS测量技术建立坝址区测绘基准的基本方法，主要包括:GPS测量与地面观测混合测量控制网的实用平差模型，平面控制基准的联合数据处理、基于面拟合的GPS跨河正常高差未知参数估计，河流两岸的正常高程基准的传递等。通过坝址区施工控制网点的GPS大地高和水准正常高之差，建立了坝址区似大地水准面基准模型，从而使GPS测高来代替高精度的几何水准或三角高程测量成为可能，也真正实现了GPS三维测量的目的。

Application of high- precision GPS positioning technology in establishment of engineering surveying and mapping reference at dam area

We present the ideas of using high-precision GPS measurements to establish surveying and mapping basis at dam area,including: a adjustment model for integrated surveying control network of GPS measurement and ground-based observations,which solves the united data-processing problems of plane control basis,unknown parameters estimation of the normal height difference crossing river based on surface fitting,which solves the transmission of normal height datum of two river sides.Through difference between GPS geodetic height of control area network and the normal height of the local Geoid,the baseline model of quasi-geoid at dam site is established,so that GPS high-precision instead of geometric leveling or trigonometric leveling level is possible to conduct to achieve a truly three-dimensional measurement of GPS.