Modeling And Features Of Crowd Emergency Evacuation Considering Behavior Variation Of Pedestrian Flow

In recent years,with the rapid development of social economy’s development in our country,the public places have become an important part of the resident’s daily life.These large public places have the following features: the high dense crowd,the large fluidity.Therefore,the security of these public places has become one of the most exciting fields in traffic science and engineering.In this thesis,based on the cost potential field cellular automata model,through considering the psychological characteristics of crowd under emergencies,such as panic,impulse,herd etc.,three extended cost potential field models are proposed to investigate crowd emergency evacuation to describe general system,counter-flow,poor vision system,respectively.The macroscopic behavior characteristics of pedestrians’ psychological changes and the dynamic mechanisms of pedestrian evacuation are investigated through numerical simulation and analysis.Additionally,we offer some advice on the emergency evacuation of pedestrians flow and the building facilities.The main contents of the thesis are as follows:Ⅰ.Through considering the influence of psychology tension to behavior variation of crowd under emergencies,an extended cost potential field cellular automata model considering behavior variation of pedestrian flow is established.The effects of the psychology tension,behavior variation,different proportion of pedestrian affected by the behavior variation for emergency evacuation are investigated,and the macroscopic behavior characteristics of emergency evacuation is also discussed.Based on the cost potential field function,through considering the psychological characteristics(e.g.,panic,impulse,etc..)of crowd under emergencies,the quantitative formula of behavior variation is introduced to reflect behavioral changes caused by psychology tension.Behavior variation under an emergency can also lead to an increase in the cost of discomfort,an extended cost potential field cellular automata model considering behavior variation of pedestrian flow is proposed.The numerical simulations are performed to investigate the effects of the magnitude of behavior variation on the evacuation efficiency in a room.The spatiotemporal dynamic characteristic during the evacuation process is also discussed.The results show that compared with the normal evacuation,the behavior variation under an emergency does not necessarily lead to the decrease of the evacuation efficiency.At low density,the increase of the behavior variation can improve the evacuation efficiency,while at high density,the evacuation efficiency drops significantly with the increasing amplitude of the behavior variation;the larger proportion of pedestrian affected by the behavior variation will prolong the evacuation time.In addition,the system size has no obvious effect on evacuation efficiency.Ⅱ.Combining the cost potential field cellular automata model considering behavior variation of pedestrian flow,an extended cost potential field cellular automaton is proposed to simulate pedestrian counter flow under an emergency by considering behavior variation of pedestrian flow induced by psychological tension.The influences of the psychology tension,a larger asymmetrical ratio of left walkers to right walkers for the macroscopic behavior characteristics and the phase diagram are investigated.Based on an extended cost potential field cellular automata model considering behavior variation of pedestrian flow.Considering the influence of psychological tension on the movement characteristics of the two groups pedestrians,and people prefer to walk on the right-hand side of the road for physical and social reasons in the channel.An extended cost potential field cellular automaton is proposed to simulate pedestrian counter flow under an emergency.The numerical simulations show that such as lane formation and segregation phenomenon for normal condition,and a moderate level of tension will delay the occurrence of jamming phase,and the larger asymmetrical ratio of left walkers to right walkers will improve the critical density related to the jamming phase and retard the occurrence of completely jammed phase.Ⅲ.Through considering the objective environment of poor vision,the function of visibility is introduced.An extended cost potential field cellular automata model considering visibility radius of pedestrian flow is proposed.The effects of the psychology tension,visibility radius,pedestrian density for emergency evacuation are investigated.A function is introduced to describe visibility radius caused by poor vision,which leads to the increasing cost of discomfort.An extended cost potential field cellular automata model considering visibility radius of pedestrian flow is proposed.The numerical simulations are performed to investigate the effects of factors such as psychology tension,visibility radius and pedestrian density on pedestrian evacuation.The results show that,in the process of emergency evacuation,the smaller visibility radius,the lower the evacuation efficiency;and the influence of on the evacuation efficiency is different.When the visibility radius is different,the influence of psychology tension on the evacuation efficiency is also different.The final chapter of this thesis is devoted to a summary and prospect,and points out the further study of the pedestrian flows.