Research On Dynamic Response Of Subway Station Structure In Inclined Liquefaction Field Based On Damage Theory

China is an earthquake-prone country with serious seismic damage,and with the rapid development of cities,it is inevitable that metro projects cross unfavorable strata in urban master plans,such as Nanjing Metro Line 1 and Guangdong Metro Line 2,so the seismic resistance of metro projects in unfavorable strata has become a research hotspot.Based on a subway station project,this paper investigates the dynamic response of a subway station in a tilted liquefaction site based on damage theory,and provides a theoretical basis for the future seismic protection of subway stations.The main research contents and results include the following four aspects:(1)The uniaxial tensile and compressive damage equations provided by Mazars damage theory are extended to multi-axes,and a two-scalar damage variable considering tensile and compressive stress damage is established and embedded into the classical Drucker-Prager principal structure model to establish a cyclic dynamic damage principal structure model,and the cyclic dynamic damage principal structure model is programmed by FLAC3D7.0 software.(2)The numerical analysis model of soil-subway station interaction system is established,the station adopts the cyclic dynamic damage principal structure,the numerical simulation analysis of different ground inclination and different seismic intensity is carried out,the dynamic response characteristics of the subway station and the liquefaction characteristics of the surrounding soil layer are compared and analyzed for the flat liquefaction site and the inclined liquefaction site,and it is concluded that the faster the growth of excess pore pressure at the top of the slope compared with the bottom of the slope for the inclined liquefaction site,the subway station The deflection angle and interlayer displacement are more related to the tilt angle and seismic strength of the site.(3)The development pattern of shear stress and sidewall dynamic earth compressive stress in the subway station is consistent,and the station generates larger shear stress and sidewall dynamic earth compressive stress when the super-pore water pressure grows;the appearance of ground dip increases the seismic response of shear stress and sidewall dynamic earth compressive stress in the station;compared with the tensile area generated at the bottom of the station in the horizontal liquefaction site,the top of the left wall and the bottom of the right wall of the station in the inclined liquefaction site appear as obvious tensile areas.(4)Different damage deformation occurs in the subway station under the earthquake action,and the damage factor increases with the increase of earthquake intensity and tilt angle;the weaker link of the station in the earthquake process is the connection of each member;when the subway station is established in the tilted liquefaction site,the left side wall will show obvious damage area.The developed damage principal model can better simulate the damage development law of the subway station.