Study On Evacuation And Infection Of Heterogeneous Individuals Based On Social Force Model

With the improvement of productivity,public buildings develop towards large scale and complicated functionality,which leads to dense people and complex crowd composition.Widespread concern and research are also aroused by some public safety issues,such as evacuation and infection transmission in crowded places.The crowd is not composed of individuals of uniform nature,and there are differences in physical condition,behavioral characteristics and cognitive level,which we call the heterogeneity of individuals.This paper focuses on the impact of differences in individual size and health status on evacuation and the spread of infection.It is difficult to make a more accurate evaluation by simulation with unitary individual attribute,so the factor of individual heterogeneity is important in the evacuation design of public places for people of all ages.Crowded places are also high-risk places where infection spread.If there are infected persons,the flow of crowd will accelerate the spread of infection.Understanding its inherent laws is the first step in public health prevention.The influence of individual heterogeneity in the crowd is studied from two aspects.First,this paper focuses on the evacuation process of binary mixed crowd from a single exit room,and explores the influence of size difference on evacuation efficiency.Second,taking the pedestrians’ exit process in a typical subway station as an example,the microscopic crowd infection is simulated and the effectiveness of control measures is analyzed.The main research contents of this paper are as follows:In order to explore the influence of individual size difference on evacuation,the evacuation characteristic time under ideal condition is introduced,and through theoretical calculation,it is found that the increase of size difference will reduce the evacuation characteristic time.However,the simulation shows that when the desired velocity is high,the increase of size difference will increase the evacuation time.In order to explore the internal reasons,the evacuation process of binary mixed crowd from a microscopic point of view is observed.By comparing the proportion of arch-clogging under different size differences,it is found that with the increase of size difference,the proportion of arch-clogging with longer delay time increases,which leads to the increase of total congestion delay.Furthermore,the stability of arch-clogging is analyzed,and the following conclusion is got: The delay time caused by arch-clogging increases with the increase of the proportion and size of large individual in arch-clogging cluster.The arch-clogging is dominant when the desired velocity is high,so the increase of size difference will obviously reduce the evacuation efficiency.Finally,a strategy is proposed to improve evacuation efficiency in this paper,that is,separate evacuation of large and small individuals,and the effectiveness of the strategy is verified by simulation.Then,the infection process of pedestrians’ exit process in the subway station is analyzed.In order to put forward targeted prevention and control measures to reduce the risk of infection,the influence of infection radius and infection probability are compared.The results show that the value of infection radius will significantly affect the spread of infection.Afterwards,corresponding measures are put forward,and the effectiveness of various measures are verified through simulation.The results show that infected people can be significantly reduced by setting reasonable barrier facilities and increasing pedestrian spacing.In addition,a higher desired velocity can also reduce infected people.It should be noted that the effectiveness of the measures will be weakened with the increase of total number of outbound people.Therefore,in addition to the implementation of prevention and control measures,the number of inbound people should be controlled to reduce the risk of infection spread.In short,the influence of individual heterogeneity in public buildings on evacuation process and infection spread are considered in this paper.It provides a certain reference for the rational layout of public buildings with complex personnel composition,the formulation of evacuation strategies and the formulation of prevention and control measures during the epidemic in public places.