地理信息系统和遥感在水文上的应用

地理信息系统和遥感在水文上的应用［德］Ｇ．Ａ舒尔兹１水文中的遥感采集遥感资料的探测器必须安装在进行测验的平台上。这些平台可以是：（１）地面观测平台（杆、塔、机动车）；（２）气球；（３）飞机和遥控飞行器；（４）火箭；（５）卫星。极轨卫星绕椭圆形轨道运行...

Working status of the 2nd channel sluices''''prestressed concrete piers at the Gezhouba Project

In China,the Gezhouba Project is the first one to adopt prestressed concrete peirs with large tonnage capacity,to bear huge water thrust from the gates.For the purpose of monitoring the working status of these peirs,a great number of electric dynamometers,reinforcement meters and strain gages were installed, and a lot of observation data has been obtained.The analysis is carried out with observation data of ten years since commission of the sluice.Analytical results show that the prestressing loss occurs mainly during construction period;annual average prestressing loss rate.of various dynamometers during operation period amounts to 0.45%,with minimum loss rate of 0.03% and maximum loss rate of 1.04%;since beginning of operation,the total prestressing loss rate indicated by various dynamometers amounts to 14.05% in average,which exceeds anticipated value of 12% However,the concrete's stresses at the necks of the piers are all in compression status,and the prestresses maintain in a state of higher level.The working status of prestressed piers is normal.