Modeling And Simulating Of Pedestrian Evacuation Under Typical Dangerous Scenes

The large public places provide great convenience for people's activities,such as sports,environment,religion,culture,learning,business,etc.When the major activities are carried out,the crowd in public place is in dense and crowed state.Once dangerous events occur,the pedestrians are prone to be panic.It is easy to cause the casualties and property losses when the layout of public place is unreasonable,the evacuation facilities are incomplete,and the evacuation management is not in place.When the dangers occur,we should study the dynamic diffusion characteristics of dangers and the pedestrians' movement rules.So we can formulate the reasonable evacuation strategies to control and guide the crows effectively,which can significantly reduce casualties.As the important research field of public security,the pedestrians' quick and safe evacuation in case of dangers has attracted serious attention from scholars and researchers at home and abroad.Based on the traditional pedestrian evacuation model,this paper proposes the pedestrian evacuation models under fire and smoke,toxic gas,flood and terrorist attack scene respectively.The models combine the dynamic diffusion of dangers with the pedestrian evacuation.The pedestrians' evacuation behavior and the dynamic movements with fire spreading are studied by the new models.The main researches in the paper are as follows,1.This paper proposes FFCA-Fire model combining the fire and smoke diffusion with pedestrian evacuation.The model studies the fire smoke dynamic diffusion mechanism.The fire spreads with a certain speed.The smoke produced by fire spreads upward on the early stage.When the smoke reaches the top of room,it diffuses around horizontally and spreads downward from the top of room and eventually fills the whole room.With the dynamic change of the fire and smoke,the movement behavior of pedestrians is divided into three stages: normal walk,bent-over walk,and crawl.In the new model,the influence of the fire and the smoke on the movement of pedestrians is modeled by the fire floor field and the smoke floor field respectively.In this paper,the pedestrian evacuation scenario that pedestrians evacuated from the room with fire ans smoke is described,and the numerical simulations are carried out to study the evacuation dynamics.The influences of personnel density,exit width,fire location,fire and smoke spread rate,on the evacuation efficiency are analyzed in detail.The simulation results can bring some guidance to design the building structure and make the evacuation strategy in emergency situation.2.This paper proposes FFCA-Toxic Gas model combining toxic gas(smoke)diffusing with pedestrian evacuation.The particle system of unity 3D is used to model the toxic gas(smoke)diffusion process.Pedestrians have initial health point.With the toxic gas spreads continuously,pedestrians inhale more toxic gas(smoke).When the critical inhalation volume is exceeded,the health point of pedestrians will decrease.When the health point decreases to 0,the pedestrian loses the moving ability and cannot evacuate smoothly.With the toxic gas(smoke)spreading,pedestrians' visual scope declines gradually,and pedestrians tend to move to the direction that more pedestrians moving to.Using the new model,numerical simulations are carried out to study pedestrians' evacuation dynamics from the room.The pedestrian evacuation process with toxic gas(smoke)particles diffusing is studied by plotting scenarios.The influence of the toxic gas(smoke)particles producing rate,the initial health point,the herding field,the critical particles concentration value and the guiding behavior on evacuation dynamics are analyzed in detail.Those results can bring some guidance to make the evacuation strategy in the toxic gas(smoke)diffusing environment.3.This paper proposes FFCA-Flood model combining flood spreading process with pedestrian evacuation.The dynamic spreading process of the underground flooding is analyzed.The flood water depth rises gradually,and the pedestrians' moving behavior in such situation can be described by four stages.i.e.,walk normally,walk slowly,move to shelters,and stay for rescue.The pedestrians' movement characteristics in the flooding environment are considered.During the evacuation,the pedestrian tends to move to the exits and higher place,hold the support objects,move along with the flow,and keep out of danger,which is modeled by the static floor field,height floor field,support floor field,flow floor field,and danger floor field,respectively.Using the new model,we set up the scenario that the pedestrians evacuate from the subway platform and subway train with flood for numerical simulation.The influence of water depth rising rate,the pedestrians' exit choosing behavior,the support floor field on the evacuation are analyzed in detail.The initial positions and trajectories of not-evacuated pedestrians are given.The effect of shelters on pedestrians' rescue is also studied.The results show that,pedestrians should choose the door nearest to evacuate and avoid gathering around the support objects to ensure safety evacuation.If necessary,we can set some shelters to buy some more evacuation time.4.This paper proposes FFCA-Terrorist model to study the pedestrian evacuation dynamics and police control behavior with terrorist attack(knife and ax)in public places.The movement characteristic of pedestrians,terrorists,polices and security guards and the interaction mechanism of them are analyzed.Terrorists attack on the target pedestrians,while being counterattacked by pedestrians and stopped by police and security guards.Pedestrians,polices,and security guards have different characteristics in prevailing against the terrorist.When pedestrians are attacked by terrorists,they respond with a certain probability,which can make terrorists losing their moving ability.The police can stop terrorists' attack and make terrorists losing their moving ability within a certain distance or in contact with terrorists.The security guards stop terrorists' attack and make terrorists losing moving ability when they are in contact with the terrorists.The new model takes the counteraction of four kinds of people as the breakthrough point to study the evacuation dynamics under the terrorist attack(knife and ax)environment.The effects of terrorists' number and distribution,exits' setting,polices and security guards' number,distribution and the control strategy on pedestrians' evacuation are studied in detail.The results can provide the basis and the technical support for evacuation management and control strategy for terrorists in the terrorist attack(knife and ax)environment.