Study On The Surrounding Rock Stress And Anti-freezing Measures Of Cold Zone Tunnel Based On Temperature Change

With the development of One Belt And One Road in our country,the pace of China’s infrastructure construction will be faster and faster.In the northwest of high altitude and low temperature environment,the construction of the cold zone tunnel will be more and more and the construction is getting harder.Whether in operation or construction,there is more and more frost damage in the tunnel which built in the cold region.For example,the surrounding rock of the tunnel is affected by the cold air,which forms the permafrost.When the permafrost expands,it is bound by the unfrozen surrounding rock and lining.When the tunnel design is insufficient to consider the frost heaving force,the tunnel lining concrete cracking is easy to occur under the effect of frost heaving force,which leads to the destruction of tunnel structure.In addition to the structural damage caused by frost heave action,there are other freezing hazards in the tunnel.For example,due to inadequate or ineffective drainage measures in the tunnel,the tunnel seeps and water freezes during the cold season.The tunnel arch is formed to hang ice,which leads to the violation of tunnel space.Insulation in the discharge process,drainage of groundwater,resulting in a decline in the temperature and the formation of freezing,cause the drain plug,groundwater flowing into the tunnel pavement,formed frozen on the road,which seriously affect the traffic safety of the tunnel.How to take effective measures to solve the freezing damage in the construction or operation of the tunnel in the cold region is an urgent problem to be solved.Based on the Wu Nv Feng tunnel,the author studies the freezing damage of the tunnel in the cold region.The research contents of this paper include:(1)The author has consulted the literature materials of the existing cold region tunnels at home and abroad.On the basis of this,the author analyzes the prevention and control of the freezing damage of several typical tunnels in China,and summarizes the engineering characteristics of the tunnel in the cold region and the causes of the freezing damage.(2)The author obtains the temperature field distribution law of the Wu Nv Feng tunnel through numerical simulation,and determines the negative temperature range of the tunnel.Based on this,a reasonable hypothesis is put forward for the depth of the tunnel surrounding rock.(3)The author used elastic mechanics method(theoretical analysis)and elastic-plastic mechanics method(numerical simulation)to calculate the frost heaving force in the cold region,and obtained the distribution rule of frost heaving stress and unfrozen surrounding rock.(4)The author introduced the general anti-freeze insulation measures of the tunnel in the cold region,and on this basis,summarized the anti-freezing and thermal insulation measures of some cold areas in China.(5)The author adopted single-layer plate heat transfer flow method,circular cylinder wall heat transfer flow method and finite element method to analyze the laying method and thickness of insulation layer in the cold region tunnel and obtained the range of insulation layer thickness and better insulation laying method.