Research On Construction And Operation Environment Temperature Control Of High Ground Temperature Railway Tunnel

Many railway lines are being planned and built in the western region of China.The special geological structure and super large buried tunnels in this region have made many tunnels in high temperature.The high temperature of the tunnel makes the environment temperature in the tunnel exceed the normal operation temperature of human body and machinery,which makes the tunnel construction difficult to continue,and also makes the railway face a series of safety risks in the operation period.Taking Layue tunnel and Sangzhuling tunnel as the research objects,this paper takes tunnel ventilation as the main means.According to the different climate and geological characteristics of each tunnel,the paper adopts the method of combining theoretical research with numerical simulation by programming,and deeply discusses the influence of different ventilation methods and other auxiliary measures on tunnel environmental temperature.The main research work and achievements are as follows:1.Based on the theory of heat transfer,a one-dimensional heat transfer model of surrounding rock–lining–air flow in tunnel–air duct wall–air flow in air duct along the tunnel longitudinal direction during the construction period is established.The calculation software is written to solve the temperature of dirty air flow in tunnel and fresh air flow in air duct under the condition of given inlet temperature of air flow and outlet temperature of air flow in tunnel face.The results show that:in the most difficult work area of Layue tunnel,when the construction is within 1000 m,the air temperature of the working face can meet the requirements of the specification when the air volume is just 60 m~3/s,but auxiliary cooling measures need to be taken for longer construction distance.2.The second development of the finite difference calculation software of tunnel operation temperature field is carried out to simulate the influence of natural wind and thermal insulation layer on the environmental temperature in the tunnel with high ground temperature,and the different influence laws of piston wind on ventilation and cooling of single track tunnel and double track tunnel are studied.This paper analyzes the cooling effect of sectional mechanical ventilation on the tunnel with high ground temperature and the rise of air temperature in the tunnel after the mechanical ventilation is stopped.The results show that:the natural wind has a positive and obvious effect on the reduction of tunnel wind temperature.The effect of the insulation layer is obvious,which is about 3℃lower than the maximum wind temperature in the tunnel without the insulation layer.The effect of the two-way train piston wind on cooling is limited,but the one-way train piston wind has a great influence on the wind temperature in the tunnel.3.Based on the comprehensive analysis of winter frost damage of high ground temperature tunnel in cold region,the feasibility of using heat conduction fracture zone of high ground temperature tunnel to realize winter lining antifreeze is discussed.The wind speed and ventilation frequency of mechanical ventilation are studied,and the ventilation prevention measures for different natural wind speed and driving pairs are put forward.The results show that:it is feasible to pass the ventilation through the transverse tube into the main tunnel to heat the lining of the tunnel and avoid freeze damage.The higher the speed of natural wind is,the more unfavorable it is to the tunnel antifreeze.Mechanical ventilation3.0 m/s can achieve the same antifreezing effect 2 hours per day less than mechanical ventilation 1.6m/s.