Study On Optimized Setting Theory And Method Of Rescue Sites For High Speed Railway Bridge

The train accidents have occurred occasionally in the world, which attach great importance to safety of the high-speed rail and timeliness of railway rescue. The bridges take a greater proportion in the high-speed rail, and rescue work is extremely difficult on the bridge. For enhancing the high-speed rail security, the rescue site is a necessary and feasible disaster prevention facility.At present, the reseach about rescue sites on high speed railway bridge is in its infancy. The systematic engineering is not perfect enough. The standards have yet to be worked out. And the optimized setting theory and method is still a blank. Around the rescue point layout optimization problem, the main work and conclusions are as follows:(1) By researching the concept and the structural composition of the rescue point for bridge, four setting modes of rescue point on bridge have been proposed, including vertical evacuation mode, longitudinal evacuation mode, lateral evacuation mode and composite mode. The suggestions on the arrangement type of vertical evacuation mode have been given according to analyzing and comparing the escape efficiency of four vertical evacuation routes. The cross passage interval and width have been researched, and two arrangement types have been presented, including longitudinal arrangement at uniform intervals along the platform and at either end of the platform.(2) The rescue point layout optimization problem has been discussed for safe evacuation, and the grading standard of the rescue point has been presented. Firstly, the psychology and behavior of passengers when evacuating urgently has been investigated and analyzed. Secondly, FDS has been applied to simulate the scene when fire occurs in the middle and head of the train respectively. And EVACNET4 has been used to simulate the evacuation along platform on the rescue point. The influence of the fire warning area on platform length and platform width on evacuation time have been researched. The main conclusions are as follows: ? In the view of the fire warning area, the platform with lenth of 450m is rational in economics.? The platform's width of 1.75m is the characteristic changes demarcation of evacuation time. When effective width is less than 1.75m, the evacuation time is longer obviously. When effective width is more than 1.75m,there is no obvious change presented. According to the results, it is suggested that the effective width should be 1.75m, and the corresponding structure width should be 2m. Judging on the required safety egress time on rescue point and based on evacuation properties, the rescue points have been divided into four grades, such as speediness, safety, owe safety design and unsafe design.(3) The constrained optimal method has been used to location decision-making of rescue sites for long bridges. The location decision-making model has been built by constraints of spacing, risk grade and rescue time, aiming at minimal sum of the rescue time that relief vehicles reach the rescue sites from the local rescue departments. Three constraint conditions have been researched. Firstly, the distance between two adjacent rescue sites has been studied based on factors, such as train braking distance, time range that a train reaches the rescue site and how long passengers need to go to rescue sites in the most unfavorable situation. It's suggested that when the bridge length is more than 10km, the evacuation functional rescue points should set at the intervals of 6?10km. When the bridge length is more than 20km, the fire functional rescue points should set at the intervals of 15?20km. Secondly, the operational risk factors of high-speed railway have been identified. The risk factors have been classified into two generic groups, which should be avoided and which should be aimed at. The former has been assessed based on Bayesian network. The probability grade of the risk that would damage the bridge's structure should be A or B. Finally, Dijkstra method has been introduced to seek the optimal path between the emergency officials and rescue sites, and the influence of the rescue time on the location decision-making of rescue sites has been analyzed. The rescue time that relief vehicles reach the rescue sites from each local rescue department should be less than 1h. An engineering example has been given to illustrate the decision-making steps. The result shows that this model can successfully solve the location decision-making problem of rescue sites on long bridges.(4) A calculation model of parking probability of bridge has been established according to event tree analysis method, and the judgment criteria whether need to set rescue points for the bridge in tunnel groups is proposed. The disaster-prevention method of the adjacent area composed by bridge and tunnel has been discussed. It is proposed that the adjacent bridge and tunnel should be seen as a system to arrange the rescue points according to following factors:tunnel length, line equipment number in the tunnel, service gallery, etc. Under the background of tunnel fire, two parking ways have been analyzed when the train catches fire in the high-speed railway tunnels.And a calculation model of parking probability has been built according to event tree analysis method. The calculation formula of parking probability has been deduced. Finally, the grading standard of parking probability has been given. It is suggested that the rescue point should be set on the bridge if the probability that the train parks on the bridge reaches 0.3 once catching fire in the adjacent tunnels.(5) The multiple objective decision with finite alternatives has been studied. The decision model for the setting plans of the rescue site has been built based on Vague Set. Finally, an engineering example has been given to illustrate the decision-making steps. The result shows that this model can successfully solve the setting plans decision-making problem of rescue sites for bridge.