Study On The Control Of The South-to-North Water Transfer Project During Freezing Period

The South-to-North Water Transfer Project is the world’s most magnificenttrans-basin water transfer project. The project will effectively resolve the seriouswater shortage problems in northern China. It will establish a reasonable dispositionof the water resources and will promote the country’s economy, society and theecological environment coordinated development. To guarantee the project securityand to reach the water distribution goal must solve the problems below: research andoptimize the distribution model under the ice cover; prevent and mitigate the icedisaster.Based on the theory of open-channel flow transients，Combined with the latestresearch progress at home and abroad，this paper establishes a simulation model tocomputes the hydraulic transients during the initial freezing period. By calculatingand analyzing the formation of ice-cover under different operation mode, found thatthe formation of ice-cover can be divided into two stages. In each stage, the hydraulicparameters show different characteristics.The deflection of the ice cover and the water level changes under ice-cover aredifferent. In order to maintain the stability of ice-cover, the water level changes areimportant. An ice-cover stability test is carried out in the ice model tank in the TianjinUniversity. A finite element model has beem build. The calculation results are veryclose to the experimental data. With the finite element model, this paper discusses theallowed water level changes uner ice-cover of different width and thickness.Based on the theory of pipe flow transients, this paper establishes a simulation modelto computes the hydraulic transients during the freezing period. The formula tocalculate the wave velocity under ice-cover is derived and the wave velocity of themodel channel is about170m/s. Take the upstream constant levercontrol for example,determined the scope of runoff and put forward a method to calculate the limitwater-hammer easily. The step-by-step method of flow regulation can effectivelyreduce the water-hammer during large flow adjustment.