Analysis Of Tunnel Vibration Response And Operation Settlement Under Train Load In Loess Area

With the rapid development of underground rail traffic,the deformation and vibration of soil caused by subway train load become an important factor affecting the safety of metro operation.At present,the study about dynamic characteristics of loess under dynamic load and deformation mostly based on the earthquake,but the study of dynamic characteristics and deformation under the long-term train load are relatively few.Based on the above two points,this paper make the following research:1)Through vibration triaxial test,study relations of dynamic stress,dynamic strain and dynamic stress,residual strain in unsaturated loess area.we learn that under the same dynamic strain the higher confining pressure,consolidation stress ratio,the greater the dynamic stress amplitude.2)Through the cyclic triaxial test,the residual strain of unsaturated loess will increase with the increase of the amplitude of dynamic stress.3)Using ABAQUS numerical to analyze we can learn that vertical direction vibration response is greater than the horizontal vibration response;The surface vibration response well occur " Local amplification " phenomenon when there is some distance away from tunnel axis;Ground vibration response near the surface and tunnel adjacent area appears the phenomenon of "local amplification;the lower the load frequency,the greater the vibration response of the earth's surface;Soil outside the tunnel adjacent area,the lower frequency vibration response is;Different tunnel adjacent area of the soil,the vibration response is not the same,the acceleration response of the high frequency load is bigger,the velocity response of low frequency load is bigger,the intermediate frequency load displacement response is larger;At the rate of a certain value,the vibration response is the largest4)Through the Chai-Miura model combining with layered summation method to calculate the surface accumulated settlement.We can learn that when the soil close to tunnel,the static and dynamic deviatoric stress distribution will mutate;At the beginning of the metro vehicle load,soil sedimentation velocity increase quickly.When settlement gradually stable over time with the increase of cycle number,maximum value subsidence of the ground is 18.0 mm and the settlement at the bottom of the tunnel is 1.07 mm.Plastic deformation mainly occurs in the adjacent tunnel area.