| As the junctions and natural barriers between regions,the rivers separate the communication between the two sides.The bridge undertakes the important function of connecting the cross-strait traffic,and it is also the key position and bottleneck of connecting the two sides.In the emergency state,once the bridge is seriously damaged,the traffic connection between the two sides will be cut off,which will seriously affect the traffic for crossing river of personnel and materials.In order to timely respond to the emergency events with bad nature,urgent time and serious damage,effective measures need to be taken at the first time to make rapid decision-making and response,so as to prevent the further expansion and escalation of the events.Therefore,the guarantee of traffic for crossing river under emergency state is particularly critical and important.Using the emergency standby bridge to restore cross-strait traffic is a main means of traffic guarantee for crossing river under emergency state.Since the current research on traffic for crossing river focuses on daily traffic and less on the emergency events of river crossing bridge damage,this paper takes the traffic for crossing river in the emergency state of bridge damage as the research object,and carries out the research from the aspects of emergency standby bridge location selection,emergency transportation route selection and so on.Based on the analysis of the research status at home and abroad,firstly,this paper describes the function and location principle of emergency standby bridge,and constructs the location model of standby bridge.Then,based on the operating conditions of the standby bridge site,the construction time of the bridge site and the material transportation time,the selection model of emergency transportation route is proposed.Finally,the proposed theoretical model is applied to a case,and the relevant contents of the emergency river crossing traffic guarantee mechanism are added,so as to provide theoretical guidance and technical support for the construction and guarantee of traffic for crossing river in emergency.The research content of this paper mainly focuses on the following aspects:(1)The site selection model of standby bridge for emergency river crossing is constructed.Firstly,based on the set emergency scenario,determine the functional positioning of the standby bridge.Secondly,based on the analysis of the influencing factors of bridge location,12 qualitative location principles are proposed,and the candidate set of emergency standby bridge location is determined based on this.Then,aiming at the minimization of the number of bridge sites and the minimization of material transportation distance,an emergency standby bridge site selection model is constructed.Finally,the applicability of tabu search algorithm is analyzed,and the site selection model is solved to obtain a set of optimal emergency standby bridge location scheme.(2)An emergency transportation route selection model is proposed.Firstly,combined with the analysis of the actual scene of emergency state,explore the enabling conditions of emergency standby bridge.Secondly,based on the construction time of bridge site and the transportation time of emergency materials,the emergency transportation route selection model is proposed,and the emergency transportation route mode of "one main and two auxiliary" is formulated.Finally,the applicability of the path planning algorithm is analyzed,and the A* algorithm is used to solve the shortest path.(3)Case application is carried out.Firstly,the emergency standby bridge location scheme is obtained by solving the location model.Secondly,based on the use of emergency standby bridge,the transportation route selection scheme of bridge construction materials and emergency demand materials is obtained by using the route selection model.Finally,formulate an emergency cross river traffic guarantee mechanism to ensure the accurate implementation of emergency decisions from the three stages of preparation,response and recovery. |
