Research On Seismic Isolation Performance Of Bituminous Backfill Grouting Material For Shield Tunnel

China is a country with frequent earthquakes.The basic seismic intensity is above 6 degrees in large area of our country.And China has a large number of tunnel projects located in high-intensity seismic regions in process of the development and construction.Tunnel engineering is safer during earthquakes than other buildings on the ground like bridge structures and tower block.However,a large number of tunnels still suffer from various damages under strong earthquake.And the post-disaster repair is extremely difficult because of the complexity of the environment.Therefore,the research on seismic isolation of tunnels is of great significance to the construction of tunnels and the design of seismic isolation in China.In this article,combined with the grouting technology of shield tunnel,the mixing ratio of asphalt grouting materials is firstly studied based on the current research of tunnel seismic isolation.Then the mechanical properties of the specimen made from asphalt grouting materials according to the optimal mixing ratio are analyzed by compression experiments.Furthermore,the dynamic response of the tunnel and the setting parameters of the seismic isolation layer are studied in case of practical engineering.The main achievements are as follows.(1)The mixing ratio of asphalt-based grouting materials is studied by the uniform test design method and the raw materials includes emulsified asphalt,cement,bentonite and water reducer.The influence of various factors of slurry on its performance are analyzed according to the requirements of post-grouting construction of shield tunnel,which can provide a reference for the application of the slurry in engineering.(2)The strength characteristics of asphalt-based grouting materials are analyzed through the uniaxial compression and triaxial compression experiments,and the seismic isolation performance of the material are discussed.Finally,the shear strength parameters are calculated based on the Mohr-Coulomb failure criterion.(3)Based on the actual project,a three-dimensional dynamic calculation model is established to analyze the acceleration,stress and displacement responses rules of the tunnel with grouting isolation layer.And the then a tunnel passes through the soft and hard boundary stratum is took as the background to establish a 3D dynamic model.The stress and displacement of these projects with grouting seismic isolation layer are analyzed to determine the reasonable stiffness,thickness and length of the seismic isolation layer.It can provides a reference for the seismic isolation design of engineering projects.