The Research On Coupling Of Temperature Field And Stress Field To Railway Tunnel With High Temperature

Accompanying the western development strategy to be carried out deeply, more andmore railway tunnels are constructed in the western region of China as a common structure.Because of the complicated geological areas with a lot of mountains, the tunnels’ constructionin these areas are influenced by various geological disasters, which including a seriousone——high rock temperature. High rock temperature not only affects the construction andoperation on the structure, but also has negative effects on the safety of the structure of tunnellining.In this paper, according to the research of the combination of the heat transfer theory andthe measurement in the JI WO XI GA tunnel, which located in high altitude and high rocktemperature, the author has conducted the numerical simulation by using ANSYS finiteelement software, studied initial temperature distribution features of the tunnel site in highaltitude and high rock temperature area, and then regard it as the initial conditions, studiedcarefully about the distribution of stress in secondary lining under the interaction of thetemperature field and stress field. Finally, the author studies the effects caused by thermalinsulation layer which are installed between the first lining and the secondary lining.The main work and results are as follows:(1)The distribution features of initial temperature of tunnel area is studied by numericalsimulation using the ANSYS finite element software. Then the author know that the constanttemperature layer is located26meters below the surface, and the value is about25℃, thevariable temperature layer is located between the constant temperature layer and the surface.The temperature of the variable temperature layer is influenced by the environment outsidelargely. The subsurface temperature layer is located below the constant temperature layer.(2)Comparing the initial rock temperature which were measured and the data providedby numerical simulation, and the two results are consistent with each other. So the accuracyand reliability of numerical simulation results are verified.(3)Take the initial rock temperature as the initial conditions, simulate the stressdistribution of the secondary lining on the interaction of temperature field and stress field. Asfar as the section2is concerned, the results show that the inverted arch is under tensile stressof2.09MPa when applied only gravity, the maximum value of the compressive stress appearsin spring of arch, the value is12.3MPa; when applied gravity and temperature loadsimultaneously, and tensile stress which the inverted arch sustained is increased to2.14MPa.It changes greatly. The maximum compressive stress is still appeared in spring of arch, itsvalue is8.66MPa. (4) When applied temperature load only, the tensile stress that the inverted arch sustaindecreases with time; the compress stress of the in spring of arch always increase, but thevariation is so tiny. It’s increases from8.42MPa after loading a month to8.66MPa afterloading5years.(5)According to the results of numerical simulation, the maximum temperature of thesecond lining is45.976℃after loading five days without heat insulation layer, it distributesat the edge of the outer secondary lining. The minimum temperature distributes in the invertedarch, its value is28.342℃.Then placing10cm heat insulation layer between the first liningand the second lining，the maximum temperature of the secondary lining is30.226℃afterloading five days, it also distributes at the edge of the outer secondary lining. The minimumtemperature is28.024℃, it distributes in the inverted arch. Thus, the heat insulation layercould restrain the transmission of high temperature from surrounding rock to the tunnel to agreat extent.