Study On Design Water Level For Flood Control Based On Risk Analysis

The design water level under the influence of typhoon has become one of themost important factors to determine the safety of engineering structures, constructioncosts and a reasonable structure. Under the premise of ensuring the security of coastalconstruction projects, both to avoid the economic waste, but also consider the degreeof risk of a variety of unfavorable load simultaneously, under the influence of typhoon,seek a comparison of design water level probability distribution pattern for floodcontrol based on risk analysis, this is the focus study of this paper.The field of marine environmental engineering risk analysis began in the1970s,initially mainly used in the ship. Later, and gradually risk analysis applied to marinestructures. Risk analysis can be broadly divided into three types: qualitative analysis,quantitative analysis and semi quantitative analysis. The event of a disaster does nothave serious consequences, may be according to the results of qualitative analysis,carry on qualitative risk assessment; for a high-risk coastal engineering andconstruction, need quantitative evaluation on the basis of qualitative, this can providea reliable foundation; semi quantitative risk analysis methods does not producequantitative results. There are many probability distribution pattern used to designwater level, each of them accessed through hypothesis testing, but select a differentmode of the probability distribution of the marine environment parameter designvalue, so how to get more reasonable probability distribution mode, in order to moreaccurately calculate design value of the marine environment parameters, is worthy ofattention. How on the basis of risk analysis, more accurately flood level design values,as well as a comparison of the probability distribution pattern for design water level,is the focus of this study, based on the above issues, this paper carries out researchwork are the following aspects: Firstly, a risk analysis method combines a joint probability distribution functionof typhoon surge water and upstream flood, there provide a mean both a probabilisticcharacteristics of random variables can be considered in a typhoon process, also thequantitative measure of flood control based on risk analysis. There the calculation ofdesign water level divide into two phases, first phase, taking the different randomvariables as a priority variable, get the water level joint return value by using of threekinds of two dimensional probability joint distribution function; the second phase,taking joint return value as the foundation, which is get from different priorityvariable, there introduces3risk methods, such as breakwater overtopping riskanalysis, risk analysis based on joint return level, again to resist of risk analysis, andcarry out typhoon surge and upstream flood the design values for further analysis,then to get their failure rate values.Secondly, extremum method uses a process of extreme value method” samplingmethod”, than ever before to take annual extreme value, not only to increase thesample size, but also more realistic reflection of the probability characteristics of theflood. Rank correlation analysis uses to describe the relationship between the dates.Thirdly, in this paper, taking risk rate as a measure of the probability distributionmodel pros and cons of quantitative criteria.