Study On Dynamic Performance Evolution Model Of Thin Wall Cavity Defects In High-speed Railway Tunnel Lining Vault

Today’s national railway construction industry is booming,and the vigorous promotion of high-speed railway tunnel construction has provided a powerful impetus for the rise and prosperity of the motherland.At the same time,the construction of high-speed rail has also become a symbol of China’s great power,and the focus of aid construction.It is both flowering inside the wall and fragrance outside the wall.However,with the rapid development of the high-speed railway tunnel in the motherland,some problems have followed.The more prominent problem is that some in-service tunnels have different lining void defects.The void defects in the tunnel lining will change the contact surface between the surrounding soil and the lining,resulting in uneven distribution of loads in the tunnel lining structure.In the end,it will intensify the occurrence of diseases such as falling,cracking and water leakage in the lining of high-speed railway tunnels.Therefore,this paper takes 1)The key project of the National Natural Science Foundation of China(Project Approval Number:U1434211)"Research on the state response and decay mechanism of high-speed railway tunnels with defects under the action of trains and aerodynamic loads";2)The basic scientific research business of municipal universities in Beijing Project support(FZ01);3)Beijing Natural Science Foundation General Project(Project Approval Number: 8202012);4)the2019 Beijing University of Architecture Graduate Innovation Project(31081019002)as the foundation,and combines the current situation that some domestic high-speed railway tunnel lining structures have hollow defects,and comprehensively uses numerical simulation,field investigation and theoretical analysis.The research on the dynamic response law of thin-walled void defects in high-speed rail tunnel lining under train vibration load is carried out.The key research results and research contents of this paper are as follows:(1)By reading a large number of literatures on the defects of high-speed rail tunnels for data collection and information integration,we found the cause of the hollow disease in the domestic high-speed railway tunnel and hidden hazards.After summarizing,two major causes of void defects are: 1.The hollow lining structure of the high-speed railway has a void;2.The surrounding rock of the high-speed railway tunnel and the initial support have voids.(2)This paper refers to the domestic research data of the high-speed railway tunnel disease in the tunnels during the service period and the literature.After research and analysis,the evolution law of the dynamic performance of the high-speed railway tunnel lining structure under the cavity defect is obtained.(3)Through the introduction of the classical damage constitutive model and the introduction of damage mechanics,the theoretical framework of the concrete plastic damage model and the method for determining the plastic damage parameters are explained.According to the constitutive relationship of stress and strain of concrete mentioned in the domestic "Code for Design of Concrete Structures"(GB50010-2010),the layout and establishment of the plastic damage model of concrete is carried out,and the damage effect is added to the research scope,thus deducing the concrete about pulling Damage expression forcompressive stress.Finally,according to the conclusion,the method of checking the parameters of the series of parameters of concrete plastic damage model is discussed.It has contributed a small force to the related research on the defects of thin-walled voids in the lining of high-speed railway tunnels.(4)Using ABAQUS finite element software to establish a high-speed railway tunnel model,according to the location and size of the lining structure cavity,the numerical simulation of the dynamic performance evolution of the high-iron tunnel lining vault thin-walled cavity defects,and also the high-speed rail under the surrounding rock cavity defect The dynamic response of the tunnel is simulated.Because of the actual situation,on-site data on lining vault defects is more difficult to collect.Therefore,the numerical simulation data of the dynamic response of the high-speed railway tunnel under the surrounding rock void defect is compared with the actual measured data of a certain institute,and the numerical simulation results are basically consistent with the measured results.It is proved that the research direction and results of numerical simulation are correct.(5)Through the established model to obtain the high-speed railway tunnel in the lining structure of the hollow shape(including opening,rectangle,ellipse,regular triangle,inverted triangle,hexagon,parallelogram,trapezoid,diamond)and the size changes,the lining arch The dynamic response near the headspace cavity includes the displacement,acceleration,principal stress and other parameters of the corresponding test point.After analyzing the data,it is found that the dynamic response parameters(acceleration,displacement and maximum and minimum principal stress)of the lining vault are decreasing with the decrease of the cavity size under the conditions of various shape cavity defects.On the whole,parallelogram-shaped voids,open-shaped voids,and inverted triangle-shaped voids have a greater impact on the dynamic response of the lining vault,but the overall gap is not very obvious.The data analysis results reflect the evolution of the dynamic performance of the thin-wall cavity defects of the high-speed rail tunnel lining vault,and provide a certain theoretical support for the future high-speed rail lining structure safety.