GPS-RTK技术在杭州湾跨海大桥地震勘测中的应用

Application of GPS-RTK technology to earthquake reconnaissance and survey on the gulf of Hangzhou big bridge

杭州湾跨海大桥桥址区域发现大面积天然气,采用地震方法探明该地区地层结构及油气分布状况是合理开发油气以及为保证杭州湾跨海大桥施工建设和运行安全的需要,杭州湾跨海大桥桥址水域宽20余km,条件十分困难,用常规定位测量方法作业困难是不可想象的。在实时导航定位中采用现代GPS-RTK技术,实现了水上远距离、大范围的地震勘测提供导航与实时精确定位。在该工程中采取了一些措施如GPS-RTK数据采集时间与地震勘测时间步调一致,为解决潮汐近10m高差影响采用了海边水准测量以检核GPS-RTK高程(因GPS-RTK高程测量误差较大)并采用事后差分技术来提供震源三维坐标等措施,为地震空间定位分析提供了保障。对出现的问题、解决的方法以及亟待解决的问题等在文中均有总结和论述。

A large amount of oil field is found around the gulf of Hangzhou big bridge.It is necessary to explore the stratum's structure and its state of the oil field under the sea and to ensure the bridge's construction and its safety.The water area's width of Hangzhou big bridge is more than 20 kilometers,and because of the effect of tide,the sea water flows rapidly.The storm is very strong and its elevation changes fast.The difference between slack tide and ebb-tide is about 10 meters.The work condition is hard.So it is unimaginable to use common way to navigation and surveying.The author adopted the GPS-RTK technology,which is called the advanced technique of three-dimensional space position system,and navigated the ship in the oil field at long distance and at large-scale area and helped the geologic reconnaissance with high precision.During the processing several measures are used such as:the time between GPS-RTK data collection and the geologic reconnaissance should be synchronized;leveling survey on the sea shore to check the elevation of GPS-RTK(because of its high survey error);afterwards-difference technology to provide three-dimensional space coordinate,etc.As a result,the spatial earthquake analysis reliability is ensured.The problems and their solutions are summarized in this paper too.