Study On Thermal Utilization Method And Thermal Environment Improvement In Subway Tunnel

China's "13th Five-Year Plan" emphasizes that the central city should strengthen the infrastructure connection with the surrounding cities.In response to national calls and their own actual needs,Hangzhou-Shaoxing intercity railway came into being,connected with the Hangzhou and Shaoxing subways.Nationwide,the subway system has been greatly developed in major cities,but at the same time,the problem of the thermal environment in the tunnel is also increasingly prominent.Due to the relatively small tunnel space in the metro area,the heat emitted by the train operation can not be ruled out in time.After long-term operation,the temperature of the soil around the tunnel will increase and heat accumulation will occur.The metro tunnels usually use mechanical ventilation to exclude excess heat.Although this method can achieve the effect of reducing the temperature of the tunnel,the heat is excluded directly,resulting in ta waste of heat and increasing the operation cost.Therefore,a method which can not only reduce the temperature of the soil around the tunnel,improve the thermal environment of the tunnel,but also make use of the heat is needed.This paper is based on Hangzhou-Shaoxing intercity railway project.The method s of numerical simulation and theoretical analysis are carried out to analyze two different methods of heat utilization in the tunnel,one is to use the piston wind in the tunnel for heat transfer with the soil around the tunnel in winter,and the other is to prefabricate heat transfer tube in shield tube for heat transfer with the soil around the tunnel.Both the two methods can achieve the purpose of improving the thermal environment of tunnel and the utilization of heat in tunnel.The specific research works are as follows:1.Taking the section tunnel of Hangzhou-Shaoxing Intercity Railway Project as the research object,the heat transfer theory of the piston wind and the soil around the tunnel are analyzed.The finite element simulation software Comsol is used to analyze the convective heat transfer between the winter piston wind and the soil around the tunnel,the temperature change of the piston wind and the soil around the tunnel are analyzed.Through the inlet and outlet temperature of the piston wind,the heat transfer of the piston wind can be calculated.In order to extract the heat in the piston windBetter,the heat pump unit needs to be designed.2.Taking the section tunnel and the station of Hangzhou-Shaoxing Intercity Railway Project as the Research Object,the heat transfer theory of the prefabricated heat exchange tube which is as the heat transfer in the shield segments is analyzed.The arrangement of heat exchange tubes in the shield segments,the connection method between the heat exchange tubes and series connection method of heat exchange tube between segment rings are analyzed,and the operation principle of the whole heat transfer system is analyzed.By establishing radial model,the influence of circulating water in the heat exchange pipe on the soil temperature field around the tunnel is analyzed from two conditions of refrigeration and heating.The effect of the heat exchange tubes on the bearing capacity of shield segments is analyzed from the aspects of the bearing area and moment of inertia.Through the comparison of two kinds of heat transfer methods,a more valuable method of heat transfer is selected.3.For the more practical application of the heat transfer method,the design of the heat transfer scheme is combined with the actual project,calculating the quantity of the project and estimating the cost.