Research On Stress Mechanism Of Suspension Bridge Tunnel Anchorage In Mountainous Area

With the continuous development of modern transportation system in China,the long-span suspension bridge scheme is widely used.Anchorage is an important part of suspension bridge.Its deformation,displacement and stress state will directly affect the safety performance and long-term reliability of suspension bridge.Compared with gravity anchorage;tunnel anchorage can make full use of geological conditions,reduce engineering cost and have less impact on the environment.But at present,the understanding of the calculation theory of tunnel anchorage is not mature enough.The design theory of tunnel anchorage has not formed a system,which limits the application of tunnel anchorage.Based on the engineering background of Chongqing Taihong Yangtze River Bridge,a three-dimensional finite element model is established according to the finite element analysis method and the actual construction environment.The stress mechanism of tunnel anchorage is analyzed.The stress distribution and deformation of the anchorage system are analyzed.Finally,the overload simulation is carried out.This thesis mainly carries out the following work:(1)Summarize the current research contents at home and abroad,study the approximate calculation theory of tunnel anchorage,and analyze some key problems in establishing the model,including the selection of material parameters and constitutive model;(2)Three-dimensional finite element analysis model including tunnel anchorage and surrounding rock is simulated by finite element software MIDAS-GTS to calculate the stress and displacement of tunnel anchor at different construction stages.The mechanical contact between anchor plug and rock mass and the stress variation law of rock mass are studied by finite element analysis method of contact problem,and the displacement and deformation of anchor plug body in the main cable direction under the design cable load are studied.Finally,the stability of the anchorage system under overload condition is verified by overload simulation,and the stability coefficient of the anchorage system is obtained.(3)The influence of the main design parameters of the anchorage system(cohesion C,anchorage inclination angle a,anchorage axis length L)on the directional displacement of the anchorage main cable and the stability of rock mass around the anchorage is analyzed in detail Some Suggestions on design and construction optimization are given.