In the development of China’s railroad tunnels,most of the railroad tunnels built in the 1970 s to 1990 s were straight-walled tunnels with rounded vaults and straight walls on both sides.Due to the limitations of the design and construction level as well as the years of tunnel operation,tunnel diseases have gradually come to the fore and the lining deterioration rate has been increasing,which seriously affects the safety of railroad operation.In this paper,based on the operational disease status of 79 straight-walled tunnels in service on the Xiangyu line,statistical analysis of tunnel lining disease characteristics is carried out through on-site research,and numerical calculation methods are used to investigate the typical structural disease characteristics and the mechanism of damage caused by the lining cavities and lining cracks under different surrounding rock levels,and to propose structural water leakage,cavities behind the lining,cracks,etc.for straight-walled railroad tunnels.(1)Investigated and counted the characteristics of lining diseases of straight wall tunnels in service of Xiangyu Line.By using the methods of manual knocking and ground penetrating radar detection,and combining with the data of recent autumn inspection,this paper makes a statistical analysis of the lining diseases of 79 straight wall railway tunnels on Xiangyu Line,and finds out the main location,types and distribution proportion of the types and grades of the seepage,cracks and cavities in the lining of the tunnels.The number and size of the lining voids are obviously more than those at the waist of the arch,and there are fewer voids in the side wall.Length of lining cracks mainly concentrates in 2~4m,and width mainly concentrates in 1~5mm;Seepage and drip accounted for a large proportion in the types of seepage water leakage disease,and the proportion of drip line and drip water was small,and the situation was worsened in the rainy season.(2)The damage mechanism of the typical structure of the straight wall railway tunnel is studied and analyzed.Using Midas GTS NX software,set up different levels of surrounding rock under the condition of hole behind the lining and lining crack disease characteristics typical numerical model,based on the actual working condition of diseases occurring location points strength and stress characteristics of lining structure is analyzed,through the stress,displacement and bending moment data behind the lining cavity and damage caused by the fracture mechanism is discussed.The change of cavity radial depth has little influence on the stress and deformation of the vault and the waist structure,but has great influence on the side wall and tunnel bottom.The circumfluence width of the void has the greatest influence on the force and deformation of the lining behind the void and its surrounding area,and the influence area increases with the increase of the width.The longitudinal length of the void has little effect on the lining.Cracks in the vault have a great influence on the lining of the inverted arch,and cracks in the waist of the arch have a great influence on the lining of the arch,and the influence of cracks in the waist of the arch on the lining should be paid more attention.(3)Put forward the treatment countermeasure of the lining structure of the straight wall railway tunnel.A decomposable rail car integrated operation platform has been researched and developed,which has been applied in the tunnel disease construction to reduce safety risks and improve labor efficiency.According to the actual situation of tunnel diseases in Xiangyu Railway,the paper puts forward the methods of backfill grouting,anchor net spraying,grouting sealing and installation of plastic steel truncating water tank to treat the structural diseases of lining,and provides suggestions and references for the treatment of the diseases such as cavity,crack and leakage behind the lining of the old straight wall railway tunnel. |