【作者】 刘毅；

【导师】 沈斐敏；

【作者基本信息】 福州大学 ， 桥梁与隧道工程， 2018， 博士

【摘要】 随着社会经济的不断发展,有限的地面空间已经很难继续满足城市快速发展需求,近年来,国内外很多城市都开展了集商业、娱乐、交通为一体的城市地下综合体的规划建设。城市地下综合体与传统地面高层建筑不同,具有深埋地下、单体面积大、疏散出口有限等环境特点,当发生火灾进行紧急疏散时容易出现横向疏散距离长、同一层待疏散人数多、人群易恐慌等问题。现有的疏散行为研究多基于地面高层建筑展开,其研究成果无法直接应用于城市地下综合体。因此,如何针对城市地下综合体的环境特点展开人员疏散行为研究成为了现阶段亟需解决的重要问题。本文从宏观—介观—微观三个尺度,通过构建模型、设计实验、优化算法对城市地下综合体环境中的疏散行为展开研究,主要工作内容和结果如下:(1)从宏观尺度以疏散群体为研究对象,针对城市地下综合体内待疏散人员多、疏散出口有限的特点展开研究。基于系统动力学理论构建城市地下综合体大规模群体疏散简化模型。通过与疏散模拟软件Pathfinder和FDS+Evac进行对比,结果表明:所构建的系统动力学模型具有较高的准确性,它结合了连续型模型和离散型模型的优点,在模拟计算时间不受人群规模限制的同时,还可以对群体内个体之间的相互影响作用进行描述,再现“快即是慢”等典型群体行为特征。(2)从介观尺度以疏散群体为研究对象,以疏散个体行为策略的博弈为主要研究内容,针对城市地下综合体环境中人群易恐慌的特点展开研究。基于“自私系数”和“恐慌阈值”建立了改进的群体疏散演化博弈模型,通过模拟个体疏散行为策略变化再现了人群由“非恐慌”向“恐慌”的转变过程。研究表明:在非恐慌状态下自私系数越高群体疏散效率下降越快,而降低个体的自私系数可以使群体的疏散效率保持在较高水平;在系统总收益一定的前提下,是否出现群体恐慌与人群恐慌阈值的大小有关,阈值越高群体越容易陷入恐慌而发生踩踏事故。因此建议采取合理措施降低系统的恐慌阈值,有效遏制群体性恐慌产生和扩散。(3)从微观尺度以疏散个体为研究对象,针对城市地下综合体横向疏散距离长、环境复杂的特点,对疏散过程中影响疏散路径选择行为的因素展开研究。选取F市某城市地下综合体进行现场实验;为了使研究结果更具普适性,设计并发放了 570份调查问卷增加参与人员数量,通过构建结构方程模型对问卷数据进行深入分析,结合实体实验结果最终确定了关键影响因素。研究表明:问卷调查和现场实验因为研究对象所处的应激环境不同而导致二者的研究结果存在一定差异;光照条件、路径距离(长短)、人流导向以及指示标记对人员疏散路径选择行为影响较大,且在不同应激状态下各因素的影响效果存在一定差异。(4)从微观尺度以疏散个体为研究对象,针对城市地下综合体内可疏散路径繁杂的特点,在考虑危险区域实时扩散的基础上对传统蚁群算法进行改进,建立了城市地下综合体疏散路径选择模型。研究表明:相对于传统的四边形栅格地图,改进的六边形栅格地图可以保证每次向任意方向移动距离均等,单位时间内向任意方向的移动速度相等;在一般情况下,人员移动速度vp=1.7m/s;CO浓度、O2浓度、烟尘能见度和温度四种火灾产物中,CO浓度最先达到安全临界值,以此确定火灾危险区域扩散速度vk=0.137m/s;疏散模型可以迅速为受困人员提供一条安全合理的疏散路径,大幅减少受困人员在危险区域的滞留时间(在实验场景中疏散时间减少36%),同时可以避免出现移动过程中误入危险区域或“穿墙”的现象。此外,编制了软件《智能疏散路径寻找系统》(软件登记号:2017SR530933),尝试将研究成果转化为实际应用。更多还原

【Abstract】 With the continuous development of social economy,limited space on the ground is difficult to meet the demand of high-speed urbanization.Nowadays,many cities in China and other countries have already carried out the planning and construction of their underground complexes integrating commerce,catering and entertainment.Different from traditional high-rise buildings above the ground,urban underground complexes are deeply underground,huge single size and limited in evacuation exit.Consequently,some common problems may occur during the fire emergency evacuation,such as long horizontal evacuation distance,large number of people waiting for evacuation at a same floor,the crowd panic problem,and so on.The most popular evacuation researches nowadays are mainly based on high-rise buildings above the ground,from which the research results cannot be effectively applied to solve the evacuation problems of urban underground complexes.Therefore,it is important to study and solve the existing problems on the evacuation behavior of urban underground complexes at current stage.Research in this paper was conducted in macroscopic,mesoscopic and microscopic dimensions on evacuation behavior in urban underground complexes through model construction,field experiments,software algorithms programming.The main research and results are as follow:In macroscopic dimension,the research on large-scale emergency evacuation behavior in urban underground complexes was conducted with the crowd waiting for evacuation as research object and evacuation model construction as research content.System dynamic model was applied to the construction of evacuation model through interdisciplinary methods.Compared with pretty matured simulation software for evacuation-Pathfinder and FDS+Evac,it was revealed that system dynamic model constructed in this paper was pretty high in accuracy;it integrated the advantages of both successive and discrete models and was free from the restriction of crowd size during the analog calculation;meanwhile,it was able to describe the interaction of individuals within the crowd,reproducing the typical features of group behavior:"faster is slower".In mesoscopic dimension,the panic mood of the crowd trapped in the urban underground complexes was conducted with the crowd waiting for evacuation as research object and the game of individual behavior strategies as main research content.Improved game model for the evolution of group evacuation was constructed on the basis of selfishness coefficient and panic threshold.By simulating the changes of individual behavior strategies,the model reproduced the changes from non-panic to panic mood of the crowd.The research showed that the efficiency of crowd evacuation would decrease with higher selfishness coefficient under non-panic conditions,whereas the evacuation efficiency would be higher with decreasing selfishness coefficient;when overall outcome from the system is stable,the outbreak and large-scale spread of panic was related to the panic threshold of the crowd,and the higher the panic threshold,the more likely they would fall into panic and stampede.Therefore,it was recommended that reasonable measures should be taken to reduce the panic threshold of the system to effectively suppress the occurrence of mass panic and prevent its rapid spread.In microscopic dimension,the research on the influencing factors of the behavior of evacuation route selection was conducted in light of the characteristics of long horizontal distance for large-scale evacuation and complex environment of urban underground complexes.In this research,a part area of an underground complex in city F was selected to conduct field experiments.Five different scenarios were set up to simulate the influence of different factors in the complex environment on the evacuation route selection.In order to make the research results more universal,570 questionnaires were designed and distributed to increase the number of participants.Through the construction of the structural equation model,the questionnaire data was analyzed in depth,and the key influencing factors were finally determined in combination with the results of physical experiments.The research showed that the questionnaires and field experiments had different results due to the different stress environments where the research objects in;illumination conditions,route distance,direction of pedestrian flow and instruction markers had a great influence on the evacuation route selection,and there were certain differences in the effect of various factors in different stress state.In microscopic dimension,with individual evacuees as the research object,considering the complicated evacuation routes in the urban underground complexes,ant colony algorithm was improved on the basis of considering the real-time spread of danger zone of the fire and the model for evacuation route selection of the urban underground complexes was established.The research showed that,compared to the traditional quadrilateral grid map,the hexagonal grid map used in the model would guarantee that the distance of moving in any direction was equal and the moving speed was also equal in unit time;normally,the pace of crowd is vp=1.7m/s;among the four types of products of the fire,CO concentration,O2 concentration,visibility of smoke and dust,temperature,CO concentration is the first one to reach the critical value of safety,so its diffusion velocity was used to determine the spread speed of danger zone of the fire——Vk=0.137m/s;the model could quickly provide a safe and reasonable evacuation route for the trapped people;greatly reduce their stranded time in dangerous areas and avoid straying into dangerous areas or“walk through the wall" during the movement.A software "Intelligent Evacuation Route Search System"(software registration number:2017SR530933)was programmed to try to put the research results into practice.更多还原