Research On Operation Safety Prediction Method And Measures Of Long-distance Continuous Tunnel Group

In recent years,with the rapid development of the national economy,in order to meet the travel needs of the people,the construction of expressways in China has been continuously promoted.Due to the restriction of route corridor and geological conditions,long-distance continuous tunnel groups have been formed in the western region of China.Some factors,such as the short distance between tunnels,the high tunnel line ratio,the great difference of visual environment between inside and outside the tunnel,and the unstable mental state of drivers entering and leaving the tunnel continuously,are the inducements of traffic accidents in the long-distance continuous tunnel group.Therefore,it is necessary to systematically study the characteristics of the long-distance continuous tunnel group,to find out the physiological and psychological state of the drivers in the long-distance continuous tunnel group,to predict the safety and comfort of the long-distance continuous tunnel group with different characteristics,and to design the corresponding operation safety measures.Based on the Yibin-Panzhihua expressway,this paper studies the methods and measures for the safety prediction of long-distance continuous tunnel group operation by means of data investigation,numerical simulation,questionnaire and field test,and obtains the following results:1.Through data investigation,three factors affecting the safety of tunnel group division are determined: driver’s visual distance,pollutant flow,and length of stranded vehicle.Based on different speed limits and different upstream tunnel lengths,tunnel group was composed of adjacent tunnels with longitudinal entrance spacing within 50～925m.Through the real vehicle test of the driver in the tunnel group section,the state indexes of the driver in the long-distance continuous tunnel group section are proved as follows: 20 km is taken as the comfortable driving length index of tunnel group sections;Drivers should not drive for more than 2.5 hours continuously on long-distance continuous tunnel sections;It is not advisable for drivers to go through eight tunnels in a row within 20 minutes.The tunnel group with a length of more than 3km and a number of more than 3 tunnels is determined to be a long-distance continuous tunnel group.2.Based on the statistical analysis of traffic accidents in long-distance continuous tunnel group,the types and spatial distribution of traffic accidents are found out,and nine factors affecting the safety and comfort of long-distance continuous tunnel group operation are obtained.The classification prediction principle of long-distance continuous tunnel group operation safety and comfort is given.In this paper,the weights of 9 influencing factors are calculated by the AHP-Entropy method.The characteristics of tunnel group and the orifice account for a large proportion of the weight,reaching 0.4797 and 0.2776 respectively.The classification quantization values of different influencing factors are given,and the classification prediction method of long distance continuous tunnel group operation safety is established3.The effect of shading shed,light belt and other measures is determined through questionnaire survey and field test on long-distance continuous tunnel group sections.The scheme of setting safety measures for long-distance continuous tunnel group operation is formulated,including the design scheme of light belt,approach road ring frame scheme,road widening scheme and setting scheme of multi-function transfer belt.The setting scheme of long-distance continuous tunnel group operation comfort measures is formulated,including setting scheme of shading shed,selection scheme of tunnel wall material,setting scheme of service area,setting scheme of parking area.According to the principle of each measure,the method of measure setting in stages and the priority of different measure setting are given.