Simulation Research On Pedestrian Emergency Evacuation Considering Group Effect

In recent years,with the continuous improvement and development of urban construction technology,the size and complexity of buildings have gone beyond the past and become more diversified.The increase of architectural space and plane size provides convenient conditions for the gathering of people in public space to a certain extent,but at the same time,it also causes some potential safety hazards.Therefore,the evacuation research based on group dynamics has attracted extensive attention of scholars.In public space,most pedestrians tend to choose the mode of group evacuation,while the traditional evacuation dynamic model lacks the description of group behavior.In view of this,this paper studies the dynamic characteristics of Pedestrians’ Group Evacuation in buildings by improving the original social force model,so as to lay a good theoretical foundation for the safety management of group evacuation.The details are as follows.Firstly,it explores the advantages,disadvantages and improvement methods of the basic social force model.It is pointed out that the rules and parameters of the social force model are easy to understand and have strong ductility,but they are still insufficient in the description of group model and leader dynamics.However,the basic social force model can be made better by improving the basic component,adding new forces and combining with other theoretical models,moreover,the corresponding improvement ideas are put forward.Secondly,the experiments of leaderless evacuation and the group evacuation with leaders are designed and compared with ordinary evacuation scenes.It is found that group evacuation is more efficient than ordinary evacuation.What’s more,in group evacuation,the presence of leaders can further improve the evacuation efficiency.In the mean time,there is also the phenomenon of “intimate distance” in group evacuation.The “intimate distance” in the leaderless evacuation and in the group evacuation with leaders are initially calibrated as 0.72 ± 0.31 m and 0.63 ± 0.21 m respectively.Then it is found that there is the coexistence of “attraction” and “repulsion” between leaders and team members,and its specific scope depends on the scope of leaders’ vision.Finally,based on the experimental results of the exercise,leaderless group evacuation and the group evacuation with leaders,two improved social force models,are proposed.The simulation shows that the evacuation efficiency with leaders is generally higher than that without leaders,especially when the group size is small.However,in the case of multiple exits,evacuation with leaders will lead to a large imbalance in exit utilization.To a certain extent,it reduces the advantage of evacuation efficiency with leaders.Through the further simulation of the evacuation group with leaders,it is found that the overall evacuation efficiency caused by the leader’s initial position in the center of the room is higher than that caused by his initial position near the exit or other random positions.And an appropriate proportion of leaders can lead to the optimal overall evacuation efficiency.Increasing the exit width will certainly reduce the total evacuation time,and the positive effect is the most significant when the number of leaders is moderate.The research results of this paper can provide sufficient theoretical basis for the evacuation safety,evacuation efficiency and evacuation management of group evacuation behavior.The results will also be widely used in urban transportation hub buildings and ordinary buildings to provide safety guarantee for the daily travel and living work of urban residents.