Mid-term Diversion Risk Analysis And Evaluation Based On The Joint Distribution Between The Flood Peak And Volume Of High Rockfill Dam

For the high dam built and built at the present time,because of its strong adaptability to geological conditions and relatively few construction costs,the rockfill dam has become a mainstream dam type.Because the high rockfill dam is mostly concentrated at the high mountain and canyon area,in which place the water level and flow rate vary greatly,besides the flood environment at the dam site is complex,so the study of construction flood simulation become very difficult.At the same time,construction of high rockfill dam is characterized by large quantity of dam filling,long construction period and high filling rate,and the construction diversion process throughout the entire construction period,especially in the later diversion process,diversion engineering failure light to cause project schedule delay,while the downstream of urban and rural residents life and property safety of the greater threat.Therefore,it is of certain engineering significance and research value to measure and analyze the mid-term diversion risk of high rockfill dam.In this paper,a systematic study was carried out on the calculation and analysis of mid-term diversion risk of high rockfill dams.With establishing the joint distribution of peak and quantity by Copula function,and the risk measurement model of mid-term diversion was set up based on the uncertainty of hydraulic and construction schedule.Based on that,the three parameter interval number was used to analyze the diversion risk.The main research contents and achievements of the paper are summarized as follows:(1)Based on the Copula function,the construction model joint distribution of flood peak volume was established.Using the original hydrological data to get analysised,determining the marginal distribution function of construction flood peak and volume,the calculation result fitting linear K-S test.Through the judgment of the different types of Copula function optimization,using the selected peak value linear establish joint distribution function,calculation of relevant parameters,the corresponding return period through the joint distribution function of extraction.According to the multiple ratio expansion method,the flood curve is processed to get the construction flood process line.At the same time,combined with the hydraulic uncertainty,the flood routing method was used to calculate the distribution of water level before the dam,so as to realize the dynamic analysis of the construction flood process,so as to provide basic data sources for risk calculation.(2)In order to further study the middle diversion risk factors,the paper focuses on uncertainty factors of the construction progress,the number of days month effective construction and construction strength,due to the construction characteristics of rockfill dam,combining with the related data,the dam site rainfall information,receive the monthly downtime days edge distribution function;the factors of uncertainty affecting the construction schedule analysis,focusing on the days of month effective construction and construction strength of two,due to the construction characteristics of rockfill dam,combining with the related data,the dam site rainfall information was collated,received the edge distribution function of the number of months.At the same time,calculating the construction strength data and similar engineering data,and the uncertainty of construction strength was analyzed.Finally,the results of the water level distribution in front of the dam are obtained by coupling the Monte-Carlo method.It also provides a feasible basis for the establishment of the risk measure model.After obtaining the risk measure model of the mid-term diversion of high rockfill dam,paper introducing three-parameter interval number theory,the interval range mathematical expression of decision index such as total cost of construction diversion,risk loss and shutdown days was put forward,and the weight of interval number is determined by subjective and objective method.(3)Based on the concept of relative closeness degree,the ratio between index value and reference point is calculated,and the advantages and disadvantages of diversion schemes are sorted out,so as to achieve multi-objective decision of construction diversion scheme.Finally,taking the construction diversion of a high rockfill dam for example,the risk calculation model is established,and the risk of medium-term diversion is obtained,and the diversion scheme is optimized and sorted.Through the analysis of the results,so as to provide the basis for the engineering practice.