Location And Evacuation Route Planning Of Urban Emergency Shelters From The Perspective Of Resilience

In the world’s urbanization process,the number and scale of cities are increasing,and various unknown risks restrict the sustainable development of cities,so the security issue is getting more and more attention.At present,the ability of domestic cities to resist disasters is still far from keeping up with the speed of economic development.Once major disasters hit large cities,they are vulnerable to losing their urban functions and causing significant losses.Therefore,improving the disaster prevention and reduction function of the urban system and building resilient cities have become the current research hotspot.The shelter is an important part of urban emergency management,and its resilience construction plays a positive role in preventing and resisting various natural disasters.In view of the earthquake disaster,from the perspective of resilience,this thesis conducts research on three aspects of resilience evaluation,location optimization and emergency evacuation path optimization of shelters,and expounds the connotation and evaluation model framework of earthquake resistance and disaster prevention resilience of shelters,so that shelters can stably play the basic functions in the post-disaster emergency response process.A multi-objective location model for shelters is established based on the objectives of cost,efficiency,coverage,and resilience to complete the corresponding allocation of shelters and demand points.Based on the above location model,an emergency evacuation path optimization model with road capacity constraints is constructed with the goal of time and resilience,which can improve the disaster resistance of shelters after sudden earthquake disasters and minimize the exposure time of evacuation personnel in danger.The main research work of this thesis includes the following three aspects:(1)For the evaluation of resilience to earthquake and disaster prevention of shelters,this thesis analyzes the connotation of resilience,and selects indicators suitable for shelters from three aspects,namely absorption capacity,recovery capacity and adaptation capacity,and constructs the evaluation of resilience to earthquake and disaster prevention of shelters.Fuzzy analytic hierarchy process(FAHP)is applied to determine the index weight.At the same time,it combines the cloud model theory to complete the evaluation of resilience levels of shelters.Finally,a case study of shelters in Shanghai urban area is conducted,and relevant data information on evaluation indicators is obtained based on field research obtained and geographic information system(GIS).Then,the resilience evaluation levels of31 shelters selected in the urban area of Shanghai are obtained.The results show that most of the shelters in Shanghai urban area are at a moderate level of resilience,which is more suitable for the actual construction situation.This evaluation system can effectively identify the weaknesses of shelters in responding to earthquake disasters,propose targeted measures,and summarize some management implications for improving the resilience level of shelters.(2)For the problem of emergency shelter location,this thesis proposes a multi-objective location optimization model that takes into account the objectives of cost,efficiency,coverage,and resilience,with the minimum construction cost of shelter,the minimum total evacuation distance,the maximum total evacuation population,and the maximum resilience of shelters.The resilience goal is reflected by the resilience level calculated by the resilience evaluation model for earthquake resistance and disaster prevention of shelter.In this location model,qualitative and quantitative methods are combined to deal with the uncertain environment after an earthquake,and particle swarm optimization is used to solve the model to obtain a multi-objective Pareto frontier solution set,and an optimal solution decision-making method is given.Finally,a case study of Yangpu District in Shanghai is carried out to verify the effectiveness of the model and the algorithm through comparative analysis and sensitivity analysis.The results show that the model and algorithm can effectively solve the problem of shelter location and the allocation of evacuation personnel,and combine decision-making methods to provide the most appropriate location allocation scheme.In addition,the location results that consider the resilience level of shelters are better than those that do not,and more shelters will also be established.(3)For the optimization of emergency evacuation routes,this thesis proposes a dual-objective model considering resilience and time.Based on the results of resilience location,GIS network analysis is used to calculate the shortest path group between demand points and shelters,and particle swarm optimization algorithm is used to solve the model to minimize the evacuation time and optimize the resilience of the evacuation network,obtaining the evacuation personnel grouping results for each demand point.Then,the user equilibrium principle is used to handle the traffic allocation of congested nodes,and a relatively optimal evacuation route and evacuation time are obtained.Finally,a case study using partial data from Yangpu District of Shanghai City verifies the effectiveness and feasibility of the model and algorithm.The calculation results show that the shortest path group obtained by combining GIS network analysis of road network conditions has better advantages than the shortest path group obtained by directly applying the Dijkstra algorithm.Evacuees will give priority to the roads with short walking distance,large capacity and far away from hazard.In addition,the models and algorithms are also reasonable and effective in evacuating personnel and reducing the delay time of intersection nodes.