Modeling And Simulation Of Evacuation Behavior For Blind Pedestrians Based On Cellular Automata

With the rapid growth of urban population,safe evacuation has become an important research field of public safety.In a limited space,it will often lead to high-density crowd flow,and the evacuation efficiency will be greatly reduced.In addition,the occurrence of special crowd in public will make the interaction among pedestrians,between pedestrians and the environment produce new dynamic characteristics.How to establish the mixed crowd evacuation dynamic model including blind people is worthy of in-depth study.Therefore,this thesis takes the blind group as the key research object.Considering the unique psychological and behavioral characteristics for blind pedestrians,a variety of benefit parameters are introduced to establish the corresponding cellular automata models of crowd evacuation under three different situations: with the blind under normal conditions,the indoor evacuation model considering guidance under power failure and the blind evacuation model considering the influence of obstacles.The evacuation dynamic characteristics of mixed population including blind people in different evacuation scenarios are discussed,and the generation mechanism of congestion is analyzed,which provides theoretical support for the optimization of blind evacuation strategy.The main contents are as follows:I.Evacuation behavior characteristics of mixed crowd with blind people under normal circumstances: Based on cellular automata theory,a mixed crowd evacuation model including blind people under normal conditions is established.The different influencing factors,such as crowd density,proportion of blind people,assistance probability and whether there is guidance source,are numerically simulated.The results show that the greater the proportion of blind people in the mixed population,the lower the evacuation efficiency.At low density,the guiding effect of guiding source is more beneficial to the evacuation of mixed people.With the increase of crowd density and the proportion of blind people,helping behavior can effectively speed up the evacuation and improve the evacuation efficiency.II.Evacuation behavior characteristics of mixed crowd including blind people under power failure: On the basis of the above evacuation model and considering the influence of power failure on emergency evacuation efficiency including blind people,an indoor evacuation model with guidance role is established to optimize the evacuation guidance strategy of relevant crowd.The evacuation scenes with different crowd density and different proportion of blind people are simulated,and the data of two cases with and without guidance source are compared.The results show that it is very easy to produce “edge effect” for the case without guidance source under power failure.After setting the guidance source,the “arching effect” at the exit will replace the “edge effect”.With the increase of pedestrian density,this phenomenon will become more and more obvious.III.Effect of exit obstacles on the evacuation efficiency of blind people:For in a single exit obstacle in room,the control variable method is adopted to study the effect of indoor obstacles on the blind evacuation efficiency rule.A blind evacuation model with obstacles is proposed.Considering the location,size and other factors of obstacles,different evacuation scenarios are constructed and simulated numerically.The shunt effect of obstacles is discussed and the layout strategy of obstacles is optimized.The results show that the longitudinal obstacles in front of the exit can effectively play the diversion role of obstacles when the obstacle is at a certain distance from the exit,which will improve the evacuation efficiency of the blind;A transverse obstacle of appropriate length can constrain the trajectory of the blind people and facilitate the completion of evacuation,but when the transverse obstacle is too long,it will create new jam on both sides of the obstacle and hinder the evacuation of the blind.The final chapter is devoted to a summary of the thesis and a prospect of further study.