Study On The Safety Coefficient Of Evacuation In Road Tunnel Fire

Highway tunnel is semi-closed and narrow,so high standard management mode is adopted during operation.It is reported that the accident rate in the tunnel is significantly lower than the whole line.However,the accident,especially the fire accident,is more serious than the road section outside the tunnel.Therefore,reducing the probability of tunnel fire and improving the efficiency of evacuation after disaster have become the key points of tunnel safety operation.Generally speaking,the research on tunnel fire at home and abroad mostly focuses on the aspects of combustion theory,fire scene,fire source type,structural damage,human injury,etc.And there are few researches on evacuation behavior of people under fire,which singlely adpoted numerical simulation to explore the evacuation characteristic in fire.The hypothesis of software boundary condition is given by hypothesis,which leads to the difference between the analysis result and the actual situation.The scientific and technological background of this dissertation is the National Science and Technology Support Program(2011BAG07B05-4)—Key Technology for Disaster Prevention and Mitigation of Offshore Extended Immersible Tubed Tunnel.The engineering background of this thesis is the safe operation of Hong Kong-Zhuhai-Macao immersed tube tunnel.Through theoretical analysis,numerical calculation,physical experiment,evacuation behavior measurement and other methods,this thesis has carried out a more systematic study on highway tunnel fire evacuation problem.By analyzing the effects of temperature,visibility and toxic gas on personnel evacuation in tunnel fire,the critical value of temperature-visibility-CO concentration for personnel evacuation is determined.Markov chain probability distribution statistical method was used to obtain the typical fire scenarios corresponding to the six burning scales of 5MW,20 MW,25MW,30 MW,40MW and 60 MW.The functional models of available time T(A),required time T(R)and safety evacuation coefficient of highway tunnel and their analytical expressions are established.The following studies were mainly carried out.1)Study on tunnel combustion theory and its influence on evacuation.In the case of tunnel fire,the fire products that have an important impact on personnel evacuation mainly include temperature,visibility and toxic gas.Gas temperature is of great significance in determining whether tunnel occupants and tunnel structures are exposed to heat,estimating the time required to detect fire and the possibility of fire spreading,and designing ventilation system.The visibility in the tunnel seriously affects the success rate of evacuation.Toxic gas is a direct factor affecting the fatality rate of fire evacuation.2)Study on evacuation behavior and safety evacuation coefficient model of tunnel fire personnel.Through the statistical results of the questionnaire survey,it is found that the vast majority of people know little about tunnel facilities and tunnel fire safety evacuation knowledge,and do not know the location and use of tunnel facilities.In tunnel fire,the psychological behavior of evacuation personnel is significantly related to gender,age,education level,fire education level and other factors.Based on the analysis of the basic law of tunnel fire evacuation and its influencing factors,the function model of available time and necessary time of safe evacuation is given,and finally,the function model of the safety evacuation coefficient of tunnel fire personnel is established.3)Study on typical fire evacuation scenarios based on Markov chains probability distribution statistics.By analyzing the fire scenarios of different tunnel types,the main influencing factors,the corresponding fire scenarios and the occurrence probability of that the burning vehicle ignited other vehicles in two-lane and three-lane tunnel fire accidents are obtained,and it is found that the occurrence probability of fire scenarios decreases exponentially with the increase of the burning scale.4)Study on available safe evacuation time(ASET)function model.By analyzing the factors that influence the available time of tunnel fire evacuation,combining with existing engineering examples and evacuation practice,the available time model of tunnel fire evacuation under the influence of longitudinal wind speed and combustion scale is obtained through single factor and multi-factor analysis method.5)Study on require safe evacuatio time(RSET)function model.The require time function model of tunnel fire personnel safety evacuation is discretized into four parts:evacuation preparation time,evacuation movement time,exit queuing time,and passage movement time.Different influencing factors and function solutions of these models are studied,and the require time function model of tunnel fire safety evacuation based on discrete model is finally obtained.The important boundary conditions in the model were obtained by means of outdoor measurement and physical experiment.The main innovative achievements are as follows:1)Based on the Monte Carlo method,the fire scenario analysis method of two-lane and three-lane tunnel was established,and the factors influencing the ignition conditions of burning vehicles in different sections of tunnel fire were obtained,and the occurrence probabilities of different fire scenarios and their corresponding burning scales were obtained.2)The available safe evacuation time(ASET)of personnel under the influence of temperature,visibility and CO concentration was obtained.The rule of available time for safe evacuation under the single factor of longitudinal wind speed and combustion scale was investigated.The function model of the available time of safe evacuation under the influence of longitudinal wind speed and combustion scale and its analytical formula are presented.3)The model boundary parameters of evacuation preparation time,evacuation movement time,exit queuing time,and passage movement time were obtained based on outdoor measured.A multi-component multi-cluster evacuation motion model based on reinforcement learning was established.The calculation method of evacuation movement time is given.The function model of the require safe evacuatio time(RSET)based on discrete element and its analytical formula are presented.4)The function model and analytical formula of safety factor of tunnel fire evacuation are put forward and established.The personnel evacuation model based on statistical analysis established in this dissertation provides a theoretical basis for the realization of personnel evacuation evaluation and evaluation.The model of evacuation path under reinforcement learning method provides support for numerical solution of evacuation path and personnel in tunnel fire.This dissertation puts forward the safety coefficient of evacuation in road tunnel fir,which opens up a new way of thinking and provides a new theoretical framework for fire evacuation of highway tunnel.It could realize the quantitative assessment of personnel evacuation in the existing operating tunnel,and provide scientific support for the setting and design of disaster prevention and mitigation and fire fighting facilities in the proposed tunnel.