Research On Time-varying Risk Assessment Model Of Tanker Road Transportation Route For Liquid Ammonia

Hazmat is indispensable raw materials for social production,and its demand has been increasing with the rapid development of the industry in recent years.It is a key link for road transportation to complete the " first mile " and " last mile " of hazmat transportation.Due to the poisonous,flammable,and explosive characteristics of hazmat,it is easy to cause catastrophic consequences such as leakage,fire,and explosion after an accident,and serious losses to the surrounding people and the environment.Therefore,this paper starts from the analysis of the accident cases of road transportation of dangerous materials of tanker,explores the influence scope of toxic gases under different diffusion scenarios,and analyzes the impact of changes in the transportation environment on the leakage probability and consequences of road transportation accidents of dangerous materials,then constructs a time-varying risk assessment mode of road transportation of dangerous materials based on conditional value-at-risk(CVa R),on the basis of which,sets up a route selection model.At last,it takes the liquid ammonia as an example.The result of this research can provide theoretical and technical support for avoiding high-risk route and emergency hedging.The main research are as follows:(1)Research on the occurrence mechanism of accidents in the road transportation system of tanker for dangerous materials.This research has collected 813 tankers’ data about road transportation accidents of dangerous materials,and analyzed the characteristics and laws of the accidents.Based on the Truck Sim simulation software,an in-depth study of the typical rollover accident is carried out.From the perspective of the system,it has explored the occurrence mechanism of accidents in the road transportation system of tanker for dangerous materials.(2)Research on the influence scope of toxic gases under different leakage and diffusion scenarios.Based on the Gaussian gas diffusion model,it has analyzed the concentration of toxic gas after its leakage.Taking liquid ammonia as an example,it has made use of the Matlab programming software to draw the diffusion concentration contour curve and the hazardous areas of different levels,revealed the evolution of ground concentration distribution and diffusion range under different leakage duration and diffusion duration.The simulation results can effectively predict the peak and duration of the ground concentration at the observation point,so as to guide the relevant person to have an emergency evacuation and hedging.(3)Research on the time-varying risk assessment model of the road transportation route of dangerous materials based on CVa R.It has considered the decision maker’s risk-averse level.Based on the road leakage accident probability and accident consequence under time-varying conditions,it has established the time-varying risk assessment model for road transportation routes of dangerous materials based on CVa R.(4)Application research on time-varying risk assessment for road transportation route of dangerous materials.It has established a single-objective route selection model based on risk,designed genetic algorithm(GA)to solve the model,and obtained an efficient route.It has also established a bi-objective route selection model based on risk and cost,designed the non-dominated sorting genetic algorithm of elite strategy(NSGA＿Ⅱ)to solve the model,then obtained Pareto non-dominated solutions.At last,it has verified the effectiveness and practicality of the model through the analysis of an actual case in city A’s road network.Calculating the transportation cost and time-varying transportation leakage probability of the road section.Setting the accident scenarios of the liquid ammonia leakage.Analyzing the time-varying leakage accident consequences of the road sections under different airflow direction.And obtaining the efficient liquid ammonia route selection scheme according to the algorithm.Decision makers can choose transportation routes and departure times according to the personal risk-averse level to improve public transportation safety.