Study On The Human Crowd Characteristics And Trampling And Crowding Risk In Subway Station

As an independent system,the evaluation of metro station’s operation safety can be achieved through the monitoring of passenger flow at key points.The key index of reflecting risk of passenger flow needs to be analyzing by synthesis,such as contact force between individual and the velocity changing rate when the density of passenger flow reaches a critical value especially when the body is contacting to each other.In this paper,first of all,taking the metro station as the point of view,a macroscopic model is established to simulate the passenger flow movement of typical facilities by analyzing the on-site collection data and a system is set up to simulate the distribution of passenger flow in the station.Secondly,through the study of evacuation rule,congestion and injury mechanism of high density flow in different key facilities,in view of different evacuation scenarios,field test and simulation analysis of possible contact force in the crowd are carried out.Thirdly,according to the study of mechanical stability of human body and classification of contact force,the cluster risk standard of passenger flow in metro under safety consideration based on the questionnaire survey is put forward,providing technical means for passenger flow risk and reference for operation enterprise to make management measures.This paper has mainly carried out the following aspects of study and achieved the corresponding results:(1)According to this research,the passenger flow statistics system has been secondary developed to realize detection area by accurately detecting within the minimum time granularity of passenger’s velocity,density and flow first.Then the testing equipment is installed at typical station.The passenger flow data is collected to analyze passengers’movement character and the density-velocity functional fitting relationship at typical facilities.(2)Combing the streamline of station’s passenger flow,the metro station passenger flow distribution measurement system has been constructed based on system dynamics.It can realize the fast simulation of flow distribution under the condition of known traffic input data.The fitting results can be used as the basis of risk standard analysis at the key facilities.(3)Macroscopic fluid flow model is established in high density situation in metro stations.Lax-Wendrofff difference scheme with second-order accuracy is used to solve model’s algorithm.By solving this model,flow patterns are obtained in front of bottleneck facilities,obstacles and under disturbance situations.The results show that this macroscopic model can effectively simulate passengers’ movement at typical walking facilities such as the crowd turbulence.This can provide a basic theory of establishing the contact force model with an initial distribution of passengers.(4)Contact force with personnel position and travel time,s distribution under the real scene in the light of two typical congestions and trampling scenarios are obtained with contact force field test by ensuring testers’ safety.The internal contact force analysis of mass evacuation is carried out by particle flow simulation software PFC2D and the fitting relationship among the contact force and initial density,expected velocity and the evacuation number of crowd in the course of scramble evacuation.Moreover,the curves of typical pedestrian contact force are got.(5)Based on the theory of human dynamics,a dynamic model of pedestrian walking is built on the basis of the Lagrange method.The force stability of high density pedestrian walking is analyzed.On the same time,the force curve of crowd evacuation process is used as the external excitation to load the human body model,and pedestrian walking process is carried out.Combing with the analysis of force stability and the conclusion of the safety threshold of human body’s contact force,safety grade of contact force on human body is classified.(6)The crowd risk model is established.Flow density and egress time are the key characters for panic.The panic function is established for calculating the crowd risk.Based on the specific case station and its historical passenger flow data,the flow distribution system in metro station is simulated in this paper.Accordingly,the crowd risk is calculated at typical crowded places.