| It is common that river ice arises, in varying degree, from low temperature in somesections that flowing through cold areas. This phenomenon may bring many troublescharacterized by disturbing electric power generation and water division, shorteningshipping lines, increasing load of hydraulic structures, interfering river sedimentmovement, especially producing ice dam and ice jam which can cause enormouslosses to the nation and the people. Many natural rivers and conveyance channels inhigh latitude countries are suffering from such problems, typically including Canada,Russia, American and Japan. In China, Northeast region, Xinjiang region, and YellowRiver basin have been worst affected by the above–mentioned problems. Therefore,South-to-North Water Diversion project in China, with a long span of latitude fromthe north subtropical humid climate zone to the warm-temperate semi-humid climatezone, must meet more serious challenges from water division during the ice age. It isvery necessary to research relative problems for large-scale water division projects.On the basis of former research experiences and results, this paper, choosingSouth-to-North Water Diversion project as the research object, adopts acomprehensive research method integrated theory analyses, model experiments andnumerical calculations, deeply analyses the main mechanizations and processes of theice hydraulics, and further focuses on the water division capability in the ice age andice disaster prevention and control. The main research achievements include:1、 This paper provides a radiation degree-day method for ice thicknessforecasting which both adapts to hydrostatic conditions and hydrodynamic conditions.It is characterized by its unity that a formula can describe in detail the whole processfrom ice growing to melting. Moreover, the author proposes a new set of amplitudecontrol indexes of water level for keeping ice cover stability. In South-to-North WaterDiversion project, the allowable amplitude of water level should not exceed20centimeter, and the daily allowable amplitude should not exceed15during thefreeze-up phase.2、It is reasonable that the physical model of ice jam design with gravitysimilarity as the general principle, on the basis of analyzing on the related physicalmodel rate. Through the model experiments of real ice, this paper reveals the icesubmergence mechanism and the condition of ice jam formation, and further providesthe judgment criterions on ice submergence both in the ice-flowing phase and in theice-melting phase.3、This paper builds simulation models of water division in the conveyancechannels during the ice phrase based on the formation of ice jam from icesubmergence, hydraulic thickening and mechanical thickening. And then this papernot only clarifies respectively the water division capability in the ice-flowing phrase, in the freeze-up phrase and in the ice-melting phrase, but also analyses the effect onwater division capability from the roughness and the percolation of ice jam.4、This paper also analyses the effect on the hydraulic characteristics of theconveyance channels respectively from ice cover roughness, sluice gate control andthe freeze-up length ratio (freeze-up segment/the whole channel). Two controloperation methods are provided based on the operation constraint condition forkeeping ice cover stability in the freeze-up phrase.5、In the case of South-to-North Water Diversion project, this paper, choosingreal ices as experiment materials, respectively researches the effect level, theinfluencing factors, and the failure mode due to the three kinds of forces: expansiveforce of ice cover, uplift force of ice cover and impact force between integral ices andbroken ices6、The author develops the net-style ice boom with two axes which can advancethe intercepting effect, also proposes the measurement index and calculation formulafor judging intercepting effects, then analyses on the anchor end tension, and finallydetermines the reasonable distances of the ice booms... |
PDF Full Text Request