Safety Evaluation Of Winter Operation Of Long-Distance Water Conveyance Open Channel In Severe Cold And Cold Regions

China has a vast territory and a complex climate,with large differences in temperature between the north and the south.In order to make full use of water resources and alleviate the serious shortage of water in some areas,China has invested in the construction of a large number of large-scale water diversion projects,such as the project of water diversion from the Yellow River into Qingdao,Luanhe-Tianjin water diversion project,the middle route of South-to-North water diversion project and the eastern route of South-to-North water diversion project.As an important part of the water diversion project,the open channel in severe cold and cold regions of northern China has cold winters,low temperatures and low water during the dry season,which leads to a decrease in the flow velocity and water depth of the open channel,a greatly reduced water delivery capacity,and a frost heaving damage to the basement of the channel slope.In the changing section of the open channel and the change of the channel section,ice dams are prone to occur,resulting in elevated water levels and flooding of the canal,which threatens the safety of people on both sides of the strait,seriously affecting the structural safety and water supply efficiency of the open channel.Therefore,it is very necessary to analyze and evaluate the winter operation safety of long-distance water conveyance open channel in cold regions.The purpose of this paper is to achieve the winter operation safety of the long-distance water supply open channel in severe cold and cold areas.Based on summarizing the winter operation experience of domestic and foreign water diversion canal projects,consulting a large number of documents,collecting norms,field research,and consulting experts,the winter operation safety evaluation index system for long-distance water conveyance open channels in severe cold and cold regions is constructed.Based on the characteristics of winter operation in open cold and cold areas,combined with asymmetric closeness and matter element extension,the winter safety operation evaluation model for long-distance water conveyance open channel in severe cold and cold regions is established.Taking the open channel section of the project from DATONG river to QingWangChuan as the research object,the collected engineering data is the support,the theoretical analysis is the guidance,the model calculation is the basis,and the result is re-examined as the means,and the example is verified.Firstly,by summarizing the engineering experience and the research results of the predecessors,this paper summarizes the main influencing factors of the winter operation safety of the open channel in severe cold and cold regions.Guided by WSR theory,a comprehensive system of initial classification evaluation index system is constructed.After expert discussion and discussion,the final winter operation safety evaluation index system forlong-distance water conveyance open channel in severe cold and cold regions regions is determined.Secondly,the graded quantification of the evaluation indicators should be based on the current national norms,technical regulations,and related monographs.In the absence of the above criteria,the standard values of the expert experience standard values or higher-level documents are used as reference.In addition,the analogy "Stipulation for Safety appraisal of sluice" classifies the winter operation safety level of the long-distance water supply open channel in severe cold and cold areas into Class I(safety),Class II(basic safety),Class III(unsafe),Class IV(very no Safety).Thirdly,according to the characteristics of winter operation of long-distance water conveyance open channel in severe cold and cold regions,an improved matter element extension evaluation model is adopted.Based on the quantified value of the evaluation index level,the classical matter element matrix and the node matrix are established,and the distance range of the object to be evaluated and the classical domain is calculated.The entropy weight-G1-game theory combined weight method is introduced,and the level of the object to be evaluated and the degree of bias to another level are calculated in combination with the asymmetric closeness.Finally,taking the main canal,the East 1 main canal,and the East 2 main canal of the from DATONG river to QingWangChuan as example,combined with the actual data,the improved element-element extension evaluation model is used to evaluate the three-section open channel.By calculating the maximum post progress,the operational safety level of the three sections of open channels in the winter is classified as Level II basic safety.The evaluation results are consistent with the actual situation,which verifies the scientific and practical operability of the model constructed in this paper.