Study On Risk Consequence Evaluation Of Dam Break In China Based On Cloud Model And Improved Varibale Fuzzy Sets

Risk consequence analysis is an important but relatively backward part in reservoir dam risk management.At present,most of the studies on the risk consequences of dam break are based on the accuracy and certainty of flood disaster prediction,reasoning and evaluation.Due to the neglect of the fluctuation,incompleteness and fuzziness of flood disaster situation,the evaluation model proposed lacks reliability in science and universality,and the evaluation results are difficult to provide reliable guidance for practical work.Therefore,under the financial support of the National Natural Science Foundation of China(51679222,51709239),this paper studies the consequences of the dam breach in China's reservoirs based on the uncertainty research method.The main work and achievements are as follows:(1)Construction of weight calculation model of dam break risk consequence impact factor.Based on the analysis of hazards,exposure and vulnerability indices of dam-break flood disaster system,the entropy weight method is improved by making full use of the expectation and entropy value of cloud model,which satisfies the requirement of sample amount.The weight calculation model of cloud model-entropy weight method is established.The result maintains the rationality of index weight ranking and solves the problem of over-average weight distribution under the condition of multiple samples.(2)Establishment of dam break life loss assessment model.Based on the analysis of the formation path of life loss caused by dam-break flood disaster,the index set and evaluation set of factors affecting life loss caused by dam-break are constructed.The logarithmic transformation is used to improve the variable fuzzy relative membership model,and an improved risk consequence evaluation model of dam break life loss is established.The problem of non-linear transition of membership degree of traditional variable fuzzy set method in dealing with exponential change factor is solved.The improved model is applied to risk ranking of dam life loss,and the effect of downstream risk population on risk grade is considered.The analysis results are scientific,effective and of great practical significance.(3)Construction of dam break environmental impact assessment model The theory of set pair analysis is introduced,by using the scalability of set pair connection degree and its similar connotation with that of variable fuzzy set theory,to solve the problem of variable fuzzy evaluation model and the problem that a large number of qualitative indicators in the impact assessment are difficult to objectively determine.The coupled model is applied to the engineering examples,and the analysis results are more objective and more complete to reflect the uncertainty of the dam impact on the environment.(4)Spatial distribution of vulnerability to dam-break floods in China.Combining with the study of disaster vulnerability and the existing evaluation models of weight and risk consequence,we comprehensively study the vulnerability of disaster-bearing body in the whole country under the large-scale range of dam-break risk.Based on statistics,government bulletin,bulletin on water resources and basic geographic information data,we set the map of the 31 provinces and regions of the vulnerability and spatial distribution of dam failure,according to the national classification method of natural disaster risk.The results reveal the general level,spatial distribution pattern and regularity of vulnerability to dam-break disasters in China.