Research On Water Pressure On Lining And The Stress Characteristics Of Lining Structure Of Water Rich Karst Tunnel In Urban Rail Traffic

With the development of urban rail traffic,it is inevitable for tunnel to cross a high pressure water-rich stratum.in the past, "Exclusive" principles were often used when come across high pressure water-rich stratum,Less likely to consider the water pressure,but it created many bad influences to ecosystem and engineering.In this paper,in order to protect the environment and insure the durability and safety of engineering,in the concept of taking positive measures to retain water and limit emission to design tunnel,and consider the influence of water to the stability of tunnel and lining structure.Based on the zhongliangshan tunnel of rail transit line 1,theoretical analysis and field test and numerical simulation analysis were used to study on the water pressure on lining and the stress characteristics of lining structure, the main contents and results are as follows:① Based on the investigation on the hydro-geological of the engineering,Take the analysis of the performance characteristics of stability of tunnel and lining structure,show the main performances of the influence of water to the stability of surrounding rock are decrease of cohesion and internal friction angle and effective stress,the main performances of the influence of water to the stability of lining is the splitting force to the concrete which produced by the moving water in concrete cracks and Karst water in the corrosion of steel bar.② Based on the site monitoring of lining structural stress in the tunnel construction and lining water pressure test,obtain the change regularity of the water pressure on lining in variety length of drainage failure,reveal the distribution regularity of the contact pressure between initial support structure and secondary lining,concrete stress,steel bar stress.③ On the basis of field test and numerical simulation,analysed the influence of the accessibility of drainage system laying behind the lining of tunnel on the seepage flow of the surrounding rock and reinforced zone and the secondary lining,obtained stress characteristics and the water pressure distribution regularity of the reinforced zone and initial support structure and the secondary lining in variety length of drainage failure.Using FLAC3 D to simulate the construction of tunnel, obtained the stress characteristics and the water pressure distribution regularity of the reinforced zone and initial support structure and the secondary lining in the construction of the tunnel.④ Analysed the influence of different thickness and Permeability coefficient of reinforced zones on the Seepage field and stress field and displacement field and stability of the reinforced zone and initial support structure and the secondary,obtained the distribution regularity and change characteristic of the Seepage field and stress field and displacement field of the the reinforced zone and initial support structure and the secondary and the stability of the secondary lining,also obtained the reasonable design value of thickness and permeability coefficient of reinforced zone.⑤ Aim at the problem of unsteady seepage field after the tunnel excavation,based on the Bernoulli equation and Darcy,obtained the Relationship between permeability coefficient and water pressure under the unsteady seepage flow,qualitative verified the credibility of numerical simulation.