The Research On Risk Decision Making Of Construction Diversion Scheme In Rebuilt Project Based On QRA

The diversion scheme of reconstruction projects is the main influence factor of construction scheduling,which runs through the whole process of hydropower project construction.The selecting of diversion schemes not only affects the investrment of diversion system but also relates to the security of the whole project.Different from new-built projects,the construction diversion risk of reconstruction projects is influenced by factors like the construction flood,diversion mode,control and discharge rule of the original dam,downstream cofferdam flood control standard etc.Moreover the construction diversion system can guarantee the regular operation of the original dam and provide a dry working area simultaneously.The construction diversion of reconstruction projects has numerous correlative influence factors.Hence,the effect to diversion system brought by each risk factors is difficult to define.Quantified risk assessment is a way to identify the potential risk of the diversion system through risk analysis,classify potential risks,and quantitative describe the possibility and outcome of various kind of risk.Scheme evaluation is made based on different kind of risk,which can be applied to the diversion decision of reconstruction projects.This paper mainly studies on the construction diversion risk of reconstruction projects,which use their original dams as upstream cofferdams,and provides a diversion risk evaluation model of reconstruction projects.The risk sources of reconstruction projects' construction diversion are analyzed,and the quantified risk assessment method is adopted to covert the risk value into evaluation index as well as formulate risk evaluating standard;departure functions are built,and the evaluation indexes are calculated;the construction diversion risk decision model of reconstruction project is established.Main works of this paper are as followed:(1)The risk factors of reconstruction projects' diversion are studied,and the influence of original dam's control and discharge rule is analyzed as well.By adopting Monte-Carlo method the process of construction flood is simulated.According to the indexes as water balance equation of flood routing,reservoir regulation rules,flow volume etc,the failure events are distinguished,the model of construction diversion risk calculation of reconstruction project is established.Based on boundary conditions the systematic risk of reconstruction projects' diversion can be obtained.(2)The characteristics of reconstruction projects' diversion risk decision are studied,a quantified risk assessment standard is given.And by establishing departure functions,the risk can be quantified as evaluation indexes of investment departure,value departure and risk departure etc.which established a construction diversion risk decision model of reconstruction projects based on QRA.According to different risk endurance of decision makers,different weights are empowered to the departure of investment,value and risk.By adopting TOPSIS method,each potential diversion scheme are evaluated and the recommend scheme sorting are generated.(3)Combining with the construction diversion decision of certain dam reconstruction project,risk evaluation is made to the potential construction diversion schemes of the project,and the best scheme is selected.the case of real project proved that the construction diversion risk decision model of reconstruction project this paper established possesses great research significance.