Emergency Evacuation For Elementary School Students' Group Based On Cellular Automata Model

In recent years,all kinds of accidents caused by pedestrian jams frequently happened.It not only brings huge losses to society but also seriously threatens people's life and property.Especially elementary school students' group has become as one higher risk crowds in stampede accidents because of their special psychological and behaviors characteristics.How to establish reasonable evacuation model for elementary school students' group and further to explore macroscopic characteristics and jamming mechanism of the pedestrian flows has been a key to reduce the corresponding accident.In this thesis,based on the existing cellular automata models,through analyzing the special behavior characteristics for elementary school students' group different from the normal people,such as panic,squeezing,and conformity,three emergency evacuation cellular automata models related to the room without barrier,the room with barrier and static field including different evacuation strategies are presented,respectively.By modeling and numerical simulation,the influence of special behavioral characteristic for elementary school students' group on macroscopic behavioral characteristic of pedestrian flow and evacuation dynamics mechanism are discussed.Besides,some relevant proposals have been provided for the setup of building and crowd management from the qualitative perspective.The main contents of this thesis are as follows:Ⅰ.Through considering the squeezing behavior for the elementary school students' group under emergency evacuation,a cellular automata model with squeezing behavior has been proposed and the influence of squeezing behavior on emergency evacuation of pedestrian flow is studied.On the basis of general Cellular Automata model,introduced the concept of pushing and extruding to describe own unique behavior characteristics of schoolchildren in the moving process,established corresponding Cellular Automata model of emergency evacuation.By numerical simulating,emphatically studied the influence of different density of the extruding crowd onevacuation efficiency and discussed the typical spatiotemporal dynamics characteristic in the evacuation process.The result shows that at low density,the number of people pushing and extruding has less influence on evacuation efficiency.With the increase of density,there occurs local jam in the evacuation process,as the percentage of the number of people pushing and extruding increases,evacuation efficiency dramatically reduces.When the initial density is0.7,the percentage of the number of extruding is percent 80,the evacuation efficiency reduced percent 70 relative to no extruding.Ⅱ.The aforementioned cellular automata model with squeezing behavior is extended to the room with barrier,and the influence of the interaction of squeezing behavior and barrier on evolution law and evacuation efficiency for the elementary school students' group is investigated.In addition,the reasonable layout of classroom is discussed.Based on aforementioned cellular automata model with squeezing behavior under the emergency evacuation,a cellular automata model considering different layouts of classroom is established.The numerical simulation is performed to study the influence of different layouts of classroom on evacuation efficiency.The results show that to set an aisle next the wall with exit in the classroom will be helpful to improve the evacuation efficiency.Ⅲ.As for a lecture hall with barrier,the evacuation efficiency for the elementary school students' group under two kinds of static fields is explored and the comparatively better evacuation strategy is obtained.As for a lecture hall with single exit,a cellular automata model for the elementary school students' group with consideration of different evacuation strategy and static field is set up.The numerical simulation is performed to study the relationship between the number of pedestrians,the percentage of moving pedestrians,the outflow at the exit with time step.The results show that to maximize the use of the aisle near the chairs and to avoid the jamming when pedestrians select the shortest route will have the significant influence on improving evacuation efficiency.The final chapter is devoted to a summary of the thesis and a prospect offurther study for the pedestrian flows.