Abstract: In order to explore the movement rule of evacuees during stairs merging process,and to improve the accuracy of calculation of stairs evacuation time,firstly,based on the social force model,the force conditions of evacuees were analyzed,the momentum equation and energy conservation equation were adopted to compute the change rates of momentum and kinetic energy.A stairs merging flows model was constructed to describe the process of stairs evacuation.Then,a certain stairs evacuation environment was taken as the background,the stairs merging flows time of evacuees was computed by simulating the merging flows process,and the change rule of movement state of evacuees were concluded.The results show that the number of evacuees increases gradually with the increase of time,the stable state is reached at last,and the evacuees movement rate increases first and then decreases,eventually,the evacuees movement rate reach a steady state,that the biggest difference value of evacuation time between floors can be computed by comparing actual evacuation time and the simulated evacuation time,it is 4.4 s,the effectiveness of stairs evacuation model is verified.

Key words: stairs evacuation, merging flows process, evacuation time, social force model, momentum equation, energy conservation equation