| How to ensure the resistance of safety and cold during operation of the tunnel has become a bottleneck,limiting the development of the transportation lifeline in Chinese seasonal frozen zone.This paper takes the existing YU Shuchuan tunnel of JI Tuhun railway as the research object.On the basis of fully learning from and absorbing the results of previous research,this paper puts forward a corrugated steel plate-polyurethane insulation lining(it is composed of corrugated steel plate,insulation layer and waterproof layer)to prevent frost heave by doing theoretical analysis,field monitoring and numerical simulation.It also studys the mechanical properties and insulation effect of corrugated steel plate-polyurethane insulation lining,summarizing the rapid construction technology of corrugated steel plate-polyurethane insulation lining,the temperature field formula of new insulation sleeve was also deduced and verified by field monitoring data,clarifying the change law of tunnel temperature field.It provides a reference for further improvement of the effect of control on tunnel freezing damage in seasonal frozen zone.The specific research results are as follows:(1)Aiming at the freezing damage of existing tunnels in seasonal frozen zone,The stress and strain changes of flat structure and corrugated steel structure were analyzed by numerical simulation when the tunnel vault and right shoulder were damaged by freezing(lining caving).Axial force,bending moment and displacement of high ladder temperature tunnel portal section is derived.The results show that the stress and strain control effect of corrugated steel structure is better than that of plate structure.At the same time,the finite element software was used to compare and analyze the variation law of tunnel temperature field under three working conditions: no measure,plate insulation lining and corrugated steel plate-polyurethane insulation lining.The results show that the change of temperature field along the outside and the initial support of the corrugated steel plate-polyurethane insulation lining is similar to its structure and is wavy.With the radial deepening along the tunnel,the influence of corrugated steel plate-polyurethane insulation lining structure on the internal temperature of surrounding rock gradually decreases,and the overall temperature of surrounding rock is significantly increased compared with no measures.(2)Based on the results of on-site investigation,the new rapid construction method of the corrugated steel plate-polyurethane insulation lining is summarized.With the advantages of fast construction speed,good insulation effect,preventing concrete spalling and falling,and convenient removal and replacement of the corrugated steel plate-polyurethane insulation lining,the problem of freezing damage of existing tunnels in seasonal frozen zone was solved.According to this construction method,the problems such as heavy materials,transportation and installation are solved,so that the work efficiency has been greatly improved,and the social and economic benefits are obvious.(3)A new theoretical formula of two-dimensional temperature field of thecorrugated steel plate-polyurethane insulation lining is proposed and verified by field data.The verification results show that: The temperature difference between the theoretical value and the measured value is between 0.3°C and 1.1°C,and the theoretical value is close to the measured value.The formula can quickly predict the insulation effect of the corrugated steel plate-polyurethane insulation lining and provide reference for the design of the corrugated steel plate-polyurethane insulation lining.(4)A new monitoring system of effect of the sleeve insulation for the existing tunnel in seasonal freezing area was established by installing the temperature measuring instrument and wireless acquisition device in different sections of the corrugated steel plate-polyurethane insulation lining and different depth of surrounding rock of the tunnel.The law of temperature change with time in each monitoring section of the tunnel is clarified.Focusing on the coldest months in the region,the following conclusions were drawn: At any time of the coldest month,the temperature of the monitoring points inside the second lining of the tunnel rose in a wave pattern along the longitudinal direction of the tunnel,and the temperature of the monitoring points rose gradually along the radial direction;The temperature of each monitoring point in the test section of the corrugated steel plate-polyurethane insulation lining increased significantly compared with that of the unapplied section,and the temperature of lining and surrounding rock all reached positive temperature.Through numerical simulation,the variation law of tunnel temperature field was further explored and compared with the measured value to ensure the accuracy of numerical simulation. |
