Study On The Social Force Pedestrian Simulation Model With Consideration Of Scene Heterogeneity And Information Propagation

In recent years,irregular emergencies occur frequently,which not only cause huge economic losses to the society,but also pose a serious threat to people's lives and social stability.Therefore,how to organize a rapid,orderly and safe crowd evacuation has become an important issue to be solved urgently in the emergency disposal of public emergencies.It is of great significance to carry out the research on the modeling and Simulation of pedestrian flow mechanics,behavior rules and prevention and control methods for improving the relevant theories and management level of emergency strategy in China.In this thesis,based on the social force model,in view of two situations: the bi-direction pedestrian flow in walking street and emergency evacuation in a room,three modified social force models are presented by considering the heterogeneity of the scene,group differences in behavior,and the propagation of information.The crowd behavior rule and the formation mechanism of induced congestion are explored through numerical simulation and analysis.The key factors affecting the crowd evacuation efficiency are also found.The research can provide theoretical basis and decision-making reference for the planning,design of pedestrian facilities and crowd emergency management.Three main contents are as follows:(1)Considering to the difference of attraction intensity(e.g.,shops)and position distribution in a walking street,a social force model on scene heterogeneity effect is proposed.The influence of the asymmetry of attraction intensity on the overall motion efficiency of bi-direction pedestrian flow is studied.The macroscopic behavior characteristics of pedestrian flow and the formation mechanism of some typical phenomenon are discussed.The results show that the new model can display the complex phenomena of bi-direction pedestrian flow,such as "lane formation","cluster","coexisting phase" and "jamming phase".The staggered distribution on the same sides can effectively improve the motion efficiency of pedestrians in crowded streets.The above results can provide useful reference for the space planning,scene design and management and control of crowd in walking street.(2)In view of the spread and evolution of dangerous sources,considering the propagation of dangerous information,and a parameter "trust" is introduced to describe the trust degree of pedestrian to information and a corresponding social force model is proposed.The numerical simulations are performed to study the influence of trusting degree on the emergency evacuation efficiency.The results show that the trust has little effect on the evacuation time at low density,whereas,the greater the trust is,the less the evacuation time will be at high density.In addition,to increase the trust under the weak vision will greatly improve the evacuation efficiency.The above research has a certain significance for guiding the pedestrians' decision-making and improving the crowd evacuation efficiency.(3)Regarding the spread of nervousness in emergency,a social force model considering the effect of emotional spread is presented.The influence of nervousness spread on evacuation efficiency is studied,and the cluster,conformity,spatiotemporal dynamics and other issues in the process of crowd emergency evacuation are discussed.The results show that the spread of nervousness have a significant impact on pedestrians' decision-making behavior.At a large crowd density,an appropriate tension can improve the evacuation efficiency.However,when this nervousness exceeds a critical value,i.e.,the panic emotion appears,the spread of panic will make the crowd quickly gather at the exit,as a result,a phenomenon "arching" near the exit occurs.In addition,under the influence of panic,some pedestrians will blindly follow the other crowd and linger,which will hinder the movement of other pedestrians,resulting in the decline of average escape speed and a phase transition of evacuation system from order to disorder.Finally,the evacuation time increases and the evacuation efficiency decreases.The above results can provide valuable reference for the strategies of emergency evacuation and methods of panic crowd evacuation.The final chapter of this thesis is devoted to a summary and prospect,and points out the further study of the pedestrian flows.