基于元胞自动机的地铁火灾疏散动态分析

在元胞自动机基本模型基础上,结合地铁人员疏散特征,开发一种扩展元胞自动机模型。模型采用危险度的概念来反映人员对地理位置的认识,以及火情对主观选择的影响作用,并引入附加危险度来实现人与人,人与障碍物之间的摩擦和排斥效应,该附加危险度随乘客运动实时调整。根据人行特征,采用八方向运动规则,结合人员密度确定乘客疏散速度,体现快即是慢的疏散规律。通过站台和站厅两幅总危险度图的布置,模拟整个地铁建筑中人员的逃生过程,以广州地铁二号线某中间站为例,分析了乘客高峰期和非乘客高峰期,以及地铁环境正常运行状态和火灾紧急运行状态下的疏散动态特征。仿真结果显示进入紧急模式下,即使乘客满员,楼梯和闸机的疏散能力能够满足地铁疏散要求。当预警滞后或控制不动作时,逃生所需时间有明显增加,整个疏散通道上,楼梯和站厅检票闸机处形成两处瓶颈,而且闸机疏散能力明显不足。

Simulation of Pedestrian Dynamics under Subway Fire Using Extended Cellular Automaton

Based on the basic automaton model rule, an extended cellular automaton model was brought out which included the pedestrian evacuation feature in subway platform. The conception of hazard degree was introduced to illustrate the cognition of pedestrian to situation, and the influence of fire on subjective selection. In addition, a so called additive hazard degree was brought out to realize the friction forces between the people, the repulsive forces of the wall and the barrier on human, which could be modified by the motion of pedestrian by real-time. According to the pedestrian feature, the eight-orientation rule was combined with variable moving speed under different pedestrian density to show the evacuation regulation of "fast induced slowness". Two filed maps of subway platform and exit platform were arranged to simulate the evacuation process under whole subway platform architecture. Making a middle station of Guangzhou Subway Line 2 as an example, the evacuation dynamic feature was analyzed during passenger peak time and general time, as well as platform system under normal operation mode and fire emergency mode. Results show that under the emergency mode, even if the train is packed, the stairs and the ticket examine gates meet the evacuation requirement. However, if the alarm and control system delays or faults, the escaping time increases, both the stairs and ticket examine gates induce the blocking of evacuation process, furthermore, the evacuation capacity of ticket examine gates is lack in evidence.