针对水汽辐射计观测数据和并址的GPS观测数据,用GAMIT软件求解了台站的天顶总延迟和湿项延迟.运用湿项延迟与水汽含量之间的转换关系,对GPS监测的大气可降水量与水汽辐射计观测的水汽含量进行了对比研究,得出结果:由GAMIT解算出的水汽含量与WVR观测值的差值平均值为0.02 mm,均方差为0.02 mm,由气象文件求出的水汽含量与WVR观测值的差值平均值为0.03 mm,均方差为0.02 mm.表明用地面GPS监测大气水汽含量是完全可行的.

Results of GPS positioning are usually represented in WGS-84 frame. In the applica-. tions in construction, local grid frame is usually adopted. This paper introduces two algorithms for transferring the GPS result to local grid frame,plane transfer model and the space transfer model. The plane transfer model is understandability and reliable, but it is not suitable for large area GPS network. The space transfer model can be used in large area GPS network. Space transfer model can be divided into seven-parameter and there-parameter model. Because ellipsoidal heights on Beijing-54 ellipsoid are usually not known precisely,its inference to plane coordinate precision is analyzed and we found that the precision of the plane coordinate influenced by the ellipsoidal height is very small. The difference between seven-parameter and there-parameter model also discussed.

GPS测量得到的是WGS-84中的地心空间直角坐标,而工程施工中通常使用地方独立坐标系,要求得到地方平面坐标.如何实现两者的转换,一直是工程施工中关心的热点问题.介绍了从GPS定位结果至平面坐标的两种转换模型.平面转换模型原理简单,数值稳定可靠,但只适用于小范围的GPS测量;空间转换模型可用于大范围GPS测量,按实际情况又分为7参数转换和3参数转换两种.鉴于54坐标点的大地高通常不能精确得知,对这两种转换方法得到的平面坐标的精度进行了比较,得出大地高精度主要表现为对高程的影响,对平面坐标影响较小的结论.此外,还讨论了7参数与3参数模型对转换结果的影响.

介绍GAMIT软件的参数设置,以消除或减弱GPS的主要误差,获取高质量的基线处理结果.通过对GAMIT的基线解算结果H文件的处理,求解基线的重复率,平面上重复率不超过3 mm,垂直方向不超过7 mm,并对基线解算质量进行了评定.在研究全球板块运动或区域性地壳形变时,以GPS单天解的基线结果作为输入量,考虑各期计算结果之间的相互联系,计算得到台站漂移量和漂移速度,从而得到地壳运动信息.对中国境内IGS站的算例分析表明,在ITRF2000框架下,计算出的漂移速度与IGS站提供的速度大小与方向基本一致.

This paper introduces how to solve the height anomaly of GPS points using the EGM96model,and then gain the mormal height of these points.Based on the comparison with the general fitting,something useful is reached.

For obtaining the orthometric or normal height of a point, the geoidal difference or height abnormal value needs to be known at the point. The accuracy of obtain height is determined by the accuracy of the corresponding geoidal difference or height abnormal value used. In this paper, EGM96 is used for calculating height abnormal value of any point on the earth surface. When calculating the coefficients of interpolation model of the local height abnormal value, the height abnormal values on the known points are removed first by EGM96, the remained values are used for calculation the interpolation coefficients. Then the height abnormal value of any point is calculated by the obtained interpolation model and added by the height abnormal value calculated by EGM96. This method has been used in a GPS leveling route, the improvements of height accuracy obtained are not significant. But for large area, this method should be useful for improvement of the obtained height accuracy.

We analyze the dependency of the GPS positioning precision on station location in an idealized positioning environment. Using a weighting function to account for an averaged number of satellites at different latitudes, we demonstrate that GPS positioning precision for ambiguity fixed solutions reduces when the latitude increases. We also quantify that the positioning precision in the north-south direction is worse than that in the east-west direction at all latitudes using the same approach.

沉管式水下隧道施工,是将已预制好的大型构件沉放到水中事先开挖好的沟槽中,再在水中拼装成一体的技术.为保证沉管对接精度,必须对大型构件的铸造误差进行严格控制.本文给出了如何求解构件的长度、端面尺寸、安放到设计位置后的倾斜度,进而解算铸造误差的数学模型,并应用于实践施工中,取得了较好的效果.