Research On Earthquake Disaster Risk Assessment Method Of Regional And Urban Water Supply Systems

Our country is located between the Pacific Rim Seismic Belt and the Eurasian Seismic Belt.The earthquake area is wide,the earthquake intensity is high,and the frequency of earthquakes is high.Large earthquakes will have a serious impact on the safe operation of various infrastructure including urban water supply systems.It is urgent to improve the ability of urban infrastructure to resist earthquake disaster risks.However,there is currently a lack of effective water supply system earthquake disaster risk assessment methods to identify the degree of risk and control the risk.Therefore,the importance of studying regional and urban water supply system earthquake disaster risk assessment models to provide technical support for the compilation of earthquake risk zonation map and the urgency of providing decision-making basis for government agencies has become increasingly prominent.In order to solve the difficulties and bottlenecks in the seismic risk assessment of regional and urban water supply systems,based on the basic data of the earthquake disaster risk assessment of urban water supply systems in our country and earthquake damage data,research objects were divided into regional water supply systems with macro data and urban water supply systems with refined data.Based on uncertainty and certainty modeling ideas,research was carried out around the seismic capacity assessment model and the earthquake disaster risk assessment model of the water supply system.The main works and research results are as follows:(1)A multi-source basic database and earthquake disaster database for water supply system earthquake disaster risk assessment with 720 cities in our country have been established.The feasibility of BP neural network site classification method to determine the site category was analyzed.The seismic hazard analysis method was used to calculate the probability density function of the peak acceleration of ground motion and the probability of seismic intensity,and the seismic hazard curve of each city was drawn.(2)In view of the difference in the proportion of pipes in the regional water supply network,the factors affecting the vulnerability of the pipe network were analyzed.Based on the multi-source data of the pipe network,fortification intensity,site type,population,GDP,etc.,the earthquake resistance model and evaluation system of regional water supply network were proposed and established.Based on the catastrophe progression method and the fuzzy comprehensive evaluation method,the basic seismic capacity factor,self-seismic capacity factor and comprehensive seismic capacity index of the water supply pipeline network of 720 cities in our country are respectively calculated.Regional comprehensive seismic capacity model and index classification standard were established.ArcGIS was used to calculate and draw a classification map of the basic seismic capability and comprehensive seismic capability index of the water supply pipeline network in China's mainland.Taking the Wenchuan Ms.8.0 earthquake as an example,the comparison with the actual earthquake damage of typical cities in Sichuan verified the rationality of the comprehensive seismic capacity evaluation model.It breaks through the technical bottleneck that makes it difficult to assess the difference in seismic resistance of regional water supply pipe networks.(3)The feasibility of regional water supply network risk assessment based on entropy method was analyzed.The problems of the original risk entropy model were pointed out.A regional water supply network risk entropy assessment model based on entropy theory and comprehensive risk entropy index classification were proposed and established.The risk entropy index of the water supply pipe network of 720 cities in our country was calculated,and the earthquake disaster risk entropy index classification map of the water supply pipe network in China's mainland was drawn using ArcGIS.Taking the Wenchuan Ms.8.0 earthquake as an example,the comparison with actual earthquake damages in typical cities in Sichuan and Shaanxi verified the rationality of the risk entropy assessment model.It solves the uncertainty of the earthquake disaster risk assessment of the regional water supply system,and provides technical support for the compilation of earthquake disaster risk maps.(4)The seismic vulnerability classification of water supply system facilities was carried out,the vulnerability curves of water supply system and each facility were given based on earthquake damage data,the earthquake disaster loss rate expectation index model was proposed as a risk assessment model,and the earthquake loss rate expectation index of the water supply network of 720 cities were calculated.A grading evaluation standard was established.Comparing with the risk entropy index and the assessment standard,the result showed that there was a clear positive correlation between the earthquake loss rate expectation of the water supply network and the earthquake risk entropy.The risk levels of the evaluation units were basically the same.ArcGIS was used to calculate and draw the classification map of the earthquake loss rate expectation index of the water supply system and various facilities in the China's mainland at different time scales.According to the seismic hazard curve,a model of the exceeding probability of earthquake loss at different time scales was proposed.Taking Deyang as an example,the earthquake disaster loss during the Wenchuan earthquake was calculated,and the reliability of the model was verified by comparison with the actual earthquake loss.(5)Aiming at the needs of hydraulic analysis of water supply pipe network,an improved global convergence algorithm was proposed to perform low-pressure hydraulic simulation of water supply pipe network,which solves the problem of poor convergence of Newtonian iteration in pipe network leakage analysis,making the calculation results of the water pressure of the pipe network nodes more accurate and reliable.A seismic risk assessment model of urban water supply pipe network based on hydraulic analysis and evaluation grading standards were proposed.Taking Italy's Apulian water supply pipe network as an example,a Monte Carlo flow analysis program was compiled to simulate water supply pipe networks with different intensities.The seismic risk assessment results of the urban water supply network were analyzed,and the rationality of the assessment model and classification standards were verified through the reliability analysis of the user nodes of the water supply network.(6)According to the composition characteristics of the various subsystems of the urban water supply system,the risk propagation path of the water supply system was analyzed,and the risk propagation model of the water supply system was proposed.Taking the water supply system of Karamay City as an example,the overall earthquake risk assessment of the water supply system of the city was carried out.The various risk models proposed in this paper are compared and analyzed.The case study results show that the risk entropy model,the loss rate expectation model,and the loss exceedance probability model are suitable for regional and urban risk assessment.The refined urban pipeline network data supports hydraulic analysis models,The risk propagation model and the economic loss prediction model are suitable for urban risk assessment,and the assessment results have good consistency,which can meet the diversified needs of government departments for earthquake risk assessment models.