Study On Mechanical Characteristics Of New Integrative Lining Structure Of Water-rich Tunnel And Its Engineering Application

With the rapid development of national economy,the number and mileage of high-speed railway tunnel and expressway tunnel are increasing,and the tunnel engineering is gradually developing to the complex geological environment of rich water strata and broken surrounding rock.A large number of tunnels have different degrees of leakage during construction and operation.The bearing capacity and stability of tunnel structure are greatly reduced.Through case study,this paper summarizes the harm and type of lining leakage,and analyzes the causes of leakage.In view of the causes of leakage,this paper puts forward the treatment ideas of leakage from two aspects of material and structure.Through the test of material properties,it is found that vinyl waterproof material has excellent properties,which can overcome the disadvantages of traditional waterproof board and provide a material basis for seepage treatment.The state of isolation between the first support,the waterproof layer and the second lining in the traditional lining structure is changed,and the close fitting with the first branch and the second lining can be realized.The integrated lining structure form of the second lining of the first supporting strong adhesive waterproof layer is put forward.The structure can improve the stress state of the lining structure,make the primary branch and the second lining play a synergistic bearing role,coordinate the deformation of the primary branch and the second lining,and improve the bearing capacity of the lining structure.Through the combination of numerical simulation and model test,the stress and deformation law and water pressure distribution law of integrated lining structure are discussed,which provides guidance and reference for the application of vinyl waterproof layer in engineering site and the design of lining structure.In this paper,based on the Yaojiayu tunnel of Binlai Expressway,the properties of vinyl waterproof material are studied by means of laboratory experiment,numerical simulation,model test and field test,and the stress and deformation characteristics of the new integrated lining structure are studied.The distribution law of lining water pressure and the progressive failure characteristics of lining structure provide a solution for the prevention and control of tunnel lining leakage water disease.The main work and research results are as follows:(1)The causes and types of tunnel lining leakage disease are analyzed,and the prevention and control ideas of lining leakage are put forward.Through the performance test of the material,the waterproof material with excellent properties was selected,and the impermeability,bond strength,tensile strength and extension at break of the waterproof material were tested.At the same time,two different types of composite specimens were made of waterproof board and new waterproof layer.The compressive strength and shear strength of the two types of specimens were tested,and the vinyl waterproof material was selected as the new waterproof material.(2)Based on the strong adhesion of vinyl waterproof layer,which can be closely attached to the foundation surface of primary support and second lining concrete,the integrated lining structure form of the second lining of primary support strong adhesive waterproof layer is put forward.The numerical model is established by FLAC3D to study the variation of lining water pressure under variable head height.The deformation characteristics of traditional lining structure and new integrated lining structure are compared and analyzed,and the influence of lining thickness change on tunnel lining structure deformation is preliminarily explored.(3)Based on the similarity theory,the water-rich surrounding rock section of Yaojiayu tunnel is selected as the engineering support,and the model test study on the mechanical characteristics of the lining structure of the water-rich tunnel is carried out.Through uniform hydraulic loading system and hydraulic loading system,the graded loading of ground stress and water pressure is realized,and the variation law of water pressure of lining structure under variable head height is analyzed when full sealing and drainage are used in tunnel.The stress characteristics of integrated lining structure and the progressive failure characteristics of lining structure are studied.(4)The field test of vinyl waterproof material was carried out in the project site,and the waterproof performance of the waterproof material was analyzed and evaluated dynamically.The construction of vinyl waterproof layer is fast and convenient,and has good engineering applicability,which provides a new solution and engineering reference for the prevention and control of tunnel lining leakage.