Seismic Response Of The Above-ground Structure-soil Underground Structure Interaction System

In the 21 st century,China has entered the golden age of underground space development and utilization.The main underground structures so far include: subway stations,tunnels,underground pedestrian road networks,underground railway networks,and underground integrated pipeline corridors.With the development of construction technology,the size and scale of underground structures have made great breakthroughs.Due to the limited urban underground space resources,there are more and more close-range crossing projects between underground structures and above-ground structures.The multiple reflections and refractions of seismic waves by underground structures will inevitably affect the dynamic characteristics of the site and affect the seismic response of adjacent structures.In addition,the earthquake on the ground structure will cause disturbance to the site soil and affect the seismic response of the underground structure.In the Japanese Hanshin earthquake,the Taiwan Jiji earthquake and the Wenchuan earthquake,many underground structures and adjacent ground structures were damaged.Therefore,in order to ensure the overall earthquake resistance and disaster prevention capability of the city,it is necessary to take into account the seismic performance of the underground structure and adjacent ground structures,and as a whole system,study the seismic response law of the above-ground structure-soil-underground structure system.This paper first verifies the correctness of the modeling method by simulating the shaking table test.Then through the overall three-dimensional modeling calculation of the above-ground structure-soil-underground structure.And systematically consider the space effect of the underground station,the stiffness of the surface structure,the structural structure of the surface structure and the underground station,the relative position and the basement of the surface structure,etc.Analyze the influence of several factors on the seismic response of the whole system.It can provide reference for the simplified calculation of structural design in the above-ground structure-soil-underground structure complex system.The research found that:1.By comparing the results of shaking table test and numerical simulation,it is shown that the modeling method of underground structure-soil-surface structure is feasible;2.Based on the calculation and analysis of the working conditions of this paper,the following interaction rules can be obtained:(1)Spatial effects of underground structures:(1)The spatial influence range of the surface single station is 1.50B(B is the single station width),so in the calculation of the underground structure design,the L-3B(L is the length of the underground structure)in the middle part of the underground structure can be The 3D calculation problem is simplified and calculated for the plane problem;(2)The influence range of the Y-direction end wall and the transfer node is: 0.8B2 and 1.8 B2,(B2 is the cross-transfer station Y-direction station width),and the influence range of the cross-transfer station on the Y-direction of the soil surface is 1.5B2,perpendicular to the seismic input direction,the station within the range of L2-2.6 B2 between the transfer node and the end wall can be reduced to a plane problem for calculation.(2)Impact of surface structure on soil:(1)The influence of the surface structure on the surface response of the soil is 12 times the width of the surface structure;(2)When the first-order frequency of the surface soil is close to the frequency of the surface structure,the seismic response of the surface structure is the largest;(3)The presence of the basement blocks the transmission of seismic waves and has a degrading effect on the seismic response of the soil surface.(3)Influence of surface structure on underground structure:(1)With the decrease of the stiffness of the surface structure,the interlayer displacement angle of the top of the subway station of the single station and the cross-change station increases;(2)The influence of the surface structure on the displacement response of the underground structure decreases as the distance between the two increases;(3)The presence of the basement blocks the transmission of seismic waves,and the presence of the basement reduces the inter-layer displacement angle of the subsurface structure.(4)Impact of surface structure on surface structure:(1)As the number of surface structures increases,the acceleration amplification factor and horizontal relative displacement of the surface structure will decrease.(5)The impact of underground structures on the soil:(1)In the direction of seismic wave input: the influence of the single subway station on the soil is 9 times the width of the metro station structure,and the impact of the cross-change station on the soil is 9.5 times the width of the metro station structure.(2)In the perpendicular to the ground motion input direction,the influence of the cross-transfer station on the soil is 10.7B2.(6)Impact of underground structures on surface structure:(1)Both the single station and the cross-transfer station will amplify the acceleration seismic response of the surface structure,in which the amplification effect of the single station is relatively small;(2)The influence of the underground structure on the acceleration amplification factor of the surface structure decreases as the stiffness of the surface structure decreases.