Research On The Crowd Evacuation Security Simulation Base On2-Dimensional Cellular Automata

In recent years, some large public activities has increased infrequently, especially the large public collection leads to severe clogging and traffic jams, which brings high risk of trample incidents and may cause huge casualty and property losses. According to the statistics, too many large-scale crowd trample disasters has taken placed constantly in the global range every year. At present, China is in the period of society crisis, the population of city increases rapidly, the social activities happen frequently, and the safety problems are urgently needed to be solved for the development of cities. Therefore, it is a crucial subject to grasp the characteristics of occupant’s crowding and evacuation, and to find a more scientific people evacuation mode, which can help us to seek new approaches of reducing the risk of emergency.This paper mainly studies the movement characteristics of the crowd evacuation at first. Research shows the crowd evacuation is less complex than vehicular flow, because people can move without the limit of lanes and people are more flexible and intelligent than cars. Furthermore, the walkers are easily affected by others as well as the environment around, so the mutual interaction between people in the public places are regular, it includes convergence and rejection. Take the following action of pedestrian for example, it means that the latter pedestrian walks following the former one with an uniform speed and route. When a person walks in a crowd, he must keep a sufferable distance from surrounding people as can as possible in order to avoid mutual impact, because it makes people psychological uncomfortable and makes the walk speed slower. The most differences between people and cars are that people’s collisions are permissible but vehicles’ are not. In addition, the movement of people is also influenced by surrounding environment, lanes’ conditions and emergencies. All of these local and individual interactions, environmental and lanes factors and personal properties codetermines the crowd evacuation. In the occupants’ evacuation process, the people-people interaction and the people-environment interaction are sufficiently considered in this paper, and which have been divided into (1)the exit attraction,(2)the repulsion force between people,(3)the friction between people,(4)the repulsion force between human and barrier,(5)the attraction of surrounding people.Through analyzing the existing models, a new occupant evacuation cellular automata(CA) model based on the social forces model is presented in the paper, which overcomes the shortage of simulating the high density crowd and combines the advantages that CA has sampled rules and faster calculating speed.Through the analysis of the evacuation, the paper simulated the evacuation process of a plaza with one exit, a bi-directional channel and the special structure crowd by using the model, and also presumed that a trample accident happens in the process when the density of crowd in a high level. After setting the isolated belt in the exit and the entrances of the channel, the causality in the accident sharp decreases. Simulation results show that the model has a great applicability for evacuation under the high density crowd condition and the segregation phenomena has also been found in the bi-directional pedestrian flow. Besides these, setting isolated belt near the exit and the entrances of underpass not only remarkable decreases the density and the risk of tramper disaster, but also it can increase the evacuation efficiency, so it provides a new idea for infrastructure design about the exits and entrances.