Longitudinal distribution characteristics of air temperature and influence factors in cold region tunnels
Affected by the severely cold climate,cold region tunnels are often faced with a series of frost dam-age problems,such as lining ice hanging,freeze-thaw damage or cracking,road icing and drainage system freez-ing failure,which pose great challenges to the construction and operation of tunnels. The sub-zero temperature environment is the necessary condition for frost damage in tunnels,thus mastering the longitudinal distribution of air temperature in tunnels is the basis and premise of frost damage research and engineering control measures in cold regions. However,various tunnels differ in environmental meteorology,engineering structure and traffic conditions significantly,resulting in obvious discrepancies in the longitudinal distribution characteristics of air temperature,causing many difficulties in accurately predicting and obtaining the longitudinal distribution of air temperature inside cold region tunnels. Therefore,in order to obtain the distribution characteristics and influence factors of air temperature in cold region tunnels,literature research and statistics and analysis methods were used to collect and sort the field measuring data and related influence factors of air temperature inside 52 cold region tunnels in China. According to the distribution characteristics of air temperature inside tunnels in cold regions,they are divided into three types:symmetric,asymmetric and cut-through type,and then the length and burial depth of each type of cold region tunnels are statistically analyzed. On this basis,the influential mechanism of temperature in tunnel site area,geothermal heat of surrounding rock and ventilation in tunnel on air temperature in the tunnels is discussed. Subsequently,the natural wind,engineering construction,mechanical ventilation and traffic factors that cause air flow inside the tunnel were analyzed,and then the primary and secondary influ-ence order of each factor was pointed out. The research results indicate that when the natural environmental fac-tors at both ends of the tunnel portal are basically the same and the elevation difference between the two ends of the entrance is not significant,the air temperature inside the tunnel usually shows a symmetrical distribution. When there is a significant slope inside the tunnel or it is affected by the prevailing wind direction outside the tun-nel,the air temperature inside the tunnel often shows an asymmetric distribution. When the tunnel length is short,the burial depth is small and unidirectional wind is prevalent,the air temperature distribution inside the tunnel often presents a cut-through type. In addition,in terms of the primary and secondary factors affecting the temperature distribution inside cold region tunnels,the environmental temperature in the tunnel site area(tunnel entrance and exit) plays a decisive role in the distribution of temperature inside the tunnel,the burial depth of the tunnel determining the geothermal effect has an important impact on the temperature inside the tunnel,and venti-lation is the key factor affecting the temperature inside the tunnel. Among the various factors affecting ventila-tion,natural wind and longitudinal slope design are the main factors influencing the longitudinal distribution of air temperature inside tunnels with slight entrance and exit elevation differences and short lengths and tun-nels with significant entrance and exit elevation differences and long lengths respectively,while engineering ancillary structures,mechanical ventilation and traffic factors are relatively secondary. This research will pro-vide reference for the study of frost damage,insulation laying design and operation and maintenance of cold region tunnels.
cold region tunnelfrost damagelongitudinal distribution of air temperaturestatistical analysisinfluence factors
万方数据
维普
