Research On Influence Of Traffic Factors On Temperature Field And Thermal Insulation Design Of Spiral Tunnel In Cold Area

In order to develop a country with strong transportation network,the national transportation network is being built at high latitudes and high altitudes,and highway tunnels under construction or planned to be built in cold regions are increasing in China.In view of the fact that the design of cold and heat insulation is not perfect,the spatial and temporal distribution of the temperature field of spiral cold tunnels is not clear,and the impact of traffic on the insulation design of road tunnels in cold regions is almost blank.For the cold tunnel spiral tunnel,there are problems that the cold tunnel insulation design is not perfect,the temporal and spatial distribution of the temperature field is not clear,and the impact of traffic on the insulation design has not been carried out.In view of the above problems,this master dissertation relies on the Hebei Jinjiazhuang extra-long highway tunnel project,using theoretical derivation,field testing,numerical calculation and other methods to carry out research on the influence of traffic factors on the temperature field of spiral tunnels in cold regions and insulation design.This master dissertation explores the influence of spiral tunnel curvature radius and highway traffic factors on the temperature field and insulation of cold highways.The main results and research conclusions are as follows:(1)Field test results show that: the history of the temperature outside the tunnel entrance,lining surfaceand surrounding rock are consistent with the characteristics of the sine function;the fitting results of the sine function show that as the depth of the hole increases,the average temperature of the surrounding rock temperature function becomes larger and the amplitude becomes smaller;the test section on the same side increases with the radial depth of the measuring point,the average temperature of the surrounding rock temperature function increases and the amplitude becomes smaller.(2)By comparing and analyzing the air velocity field distribution law of spiral tunnels with different curvature radius,it is found that the velocity of each measuring point along the horizontal line shows an inverted “U” distribution,the straight tunnel is a symmetric inverted “U” shape,and the peak position in the spiral tunnel is shifted to the outer diameter of the spiral tunnel,and the greater the spiral curvature,the more severe the shift.(3)The asymmetry of the air velocity distribution causes the heat transfer rate on the outer diameter side of the spiral tunnel to be greater than the inner diameter side,which ultimately results in the temperature in the outer diameter direction of the tunnel being lower than the other side of the spiral tunnel and lower than the straight tunnel under the same conditions.Therefore,the temperature field of the spiral tunnel is unfavorable to the thermal insulation design,and it should be revised accordingly during the design process.(4)The daily traffic flow has a "double hump" shape,and the temporal change of daily weather temperature is characterized by a "single peak" shape.By compiling and loading the fitting functions of the two with the udf,a fluid-structure coupling calculation model considering traffic ventilation and temperature changes at the entrance of the tunnel is established.(5)The traffic flow and peak traffic hours have a greater impact on the temperature field,and the spiral tunnel is more affected by traffic factors than the straight tunnel.The outer diameter side of the spiral tunnel is more affected by the traffic factors than the inner diameter side.(6)Based on the non-pairing of the temperature field of the highway tunnel in the cold area,a calculatingmethod for insulation length is discussed based on the traffic flow into or out of the tunnel,and the main wind direction of the tunnel is blown in or out.