A Study On Temperature Field In Rock For Seasonally Frozen Soil Tunnels With A High Altitude

With the further implementation of the western development strategy, transportation infrastructure construction in the western region is meeting a new round of summit. More and more highway tunnel projects crossing complex geological conditions are being congstructed, many of them crossing the high altitude seasonal tundra included. In winter, Seasonally frozen freezes and melts in summer,whose repeated freezing and thawing action will affect tunnel’s safety and shorten the life of the tunnel. Therefore,the study on surrounding rock’s temperature field of seasonal permafrost tunnel of high altitude plays an important role.Based on the wenma highway tunnel project crossing high altitude and seasonal tundra, this thesis studies temperature field of surrounding rock of this tunnel’s Export segment in details. The main contents are as follows:1. Through on-site monitoring,this article grasps the variation of atmospheric temperature of where tunnel stands and studies its relationship with the temperature distribution of surrounding rock. Then, cosine function curve which descript change of atmospheric temperature is obtained. The change of Atmospheric temperature conforms trigonometric curve, The curve is as follows: T=16sin(л/6t-2/3л)+82. Through monitoring the air temperature inside the tunnel at different mileage,this article studies its relationship with the temperature distribution of surrounding rock. Then,the curve descripts the change of temperature inside tunnel with vertical depth is obtained.The temperature inside tunnel also conforms trigonometric curve.3. Through monitoring temperatures of the tunnel wall rock of different vertical depth, this article studies the relationship between the temperatures of surrounding rock and vertical depth. Then,the curve descripts the change of temperature of tunnel surrounding rock with vertical depth is obtained.Before tunnel completed, temperature of Rock raises into a stable level with vertical depth increasing in winter,oppsite in summer.4. By monitoring the temperatures of same longitudinal and different radial surrounding rock,this thesis studies the relationship between the temperatures of surrounding rock and radial depth. Then,the curve descripts the change of temperature of tunnel surrounding rock with radial depth is obtained. Gradient of rock temperature is greater under1.5m,but smaller beyond1.5m.5. By using numerical calculation software FLAC3D,the thesis studies the temperature field of surrounding rock of the exit section of tunnel under different temperature conditions and predicts the distribution of temperature field of surrounding rock of the exit section of tunnel during the operational phase, when Monthly average is lower than-4Celsius, Lining completely occur negative temperature.6. after a operational phase of5year, negative temperature range up to a new stable value1.26m in rock.