Study On Navigational Dynamic Risk Assessment For Large Water Diversion Project During Construction Period

With the booming development of inland waterway economy,the freight volume of shipping and the number of large hydraulic projects increase year by year.The large hydraulic projects are complex of various types of hydraulic structures,taking into account the function of flood control,power generation,water storage,shipping etc.,Thousands of large hydraulic projects have been built in inland waterway,which occupy navigable waters range.The construction period of large hydraulic project is long involving complicated construction process.It is unavoidable to exert a negative effect on navigating ships in nearby water,which severely affects the normal traffic order and poses a huge threat to the navigational safety of ships.Meanwhile,navigational risk influence factors such as the scope of construction,the intensity of work and environmental change are variable with the construction period.Therefore,based on the dynamic risk assessment of construction period,it is vital to propose security prevention and control measures and quantificational assess the risks in different construction stages to ensure the navigation safety during the construction period.In this paper,the navigation characteristics are analyzed to identify navigational risk influence factors in large hydraulic projects.Meanwhile,the uncertainty and randomness of navigational risk influence factors are described.Risk analysis model and dynamic risk assessment model are established based the navigational characteristics and the dynamic characteristics of risk influence factors during the construction period.The main contents are shown as follows:(1)Navigational risk influence factors identification on large hydraulic project during the construction period.Constructing the navigational risk assessment method based on Formal Safety Assessment(FSA)to analyze the navigational risk during the construction period of large hydraulic project.According to the analysis of navigational characteristics during the construction period and the method framework of FSA,the research is conducted according the proposed procedure “risk identification– risk assessment/risk analysis– provision of suggestions on decision-making”.And the navigational influence risks are identified based on Human Factors Analysis Classification Systems(HFACS).According to the data source and characteristics of large hydraulic projects,information execration method based on expert inference,the approach is proposed based on Evidential Reasoning Approach,Analytic Hierarchy Process(ERA/AHP),which is used to solve the problem that individual interference information lacks completeness using Conditional Probability Table(CPT)in Bayesian Network(BN)modeling.(2)Static risk assessment modeling for large hydraulic projects during the construction period.18 major navigational risk influence factors and 4 risk probabilities are proposed in terms of 5 aspects based on the framework of HFACS.Using the BN model based on the proposed method together with 10 experts’ knowledge information,the quantitative results of CPT in BN models and navigation risk factor’s possibility of occurrence,the static risk assessment for Gezhou dam’s expansion project is realized.(3)Dynamic risk assessment modeling for large hydraulic projects during the construction period.According to the analysis of navigational characteristics during the construction period,the uncertainty and randomness of navigation risk influence factors are described to identify the dynamic risk influence factors.With the introduction of Monte Carlo Simulation(MCS),certain probabilities of dynamic risk influence factors are transferred into probability distribution.The dynamic risk assessment for Gezhou dam’s expansion project as for an example is carried out using the proposed model,the risk of ship accidents,the risk of shiplock accidents and the risk of waterway accidents can be quantized dynamically,which finally realize the dynamic assessment of navigational risk during the Gezhou dam’s expansion project.It is of great significance to dynamically assess the navigational risk during the construction period of large hydraulic project.The uncertainty of large hydraulic projects is analyzed to assess the navigational risk dynamically,which optimize the risk assessment model for large hydraulic projects during construction period.Meanwhile,the Gezhou dam’s expansion project as an example is carried out using the proposed model in order to analyze the navigational risk,which provides theoretical basis and technical support for navigational safety and risk control.