Dynamic Interaction Analysis Of Soil-Underground Structures Under Seismic Waves

Underground structures,especially tunnels,utility tunnel and underground stations,are important components of public infrastructure in modern society.However,the situation of underground structures is complex,the space scale is large,hidden safety hazards are not easy to find and maintenance is difficult.Especially,the soil along the coast is weak,the ground buildings in large and medium-sized cities are dense,and the underground pipeline system is intricate.Functional design is particularly important.In this paper,numerical simulation method is used to model and analyze the seismic response of underground structures from the innovative point of view of viscoelastic boundary,combined with ABAQUS large-scale finite element analysis software and MATLAB programming software.The specific work contents and achievements include the following aspects.(1)Seismic Response Analysis of the Utility Tunnel in Layered Site under Oblique Incident of Seismic WavesUsing ABAQUS large-scale finite element analysis software,the analysis model of utility tunnel under different site conditions is established.Based on the viscoelastic artificial boundary and the time-domain wave method of equivalent seismic load,and combined with the exact dynamic stiffness matrices of soil layer and half-space,seismic response analysis of the utility tunnel in layered site under the obliquely incident of seismic wave is realized.It can be concluded that the dynamic responses of the utility tunnel subjected to the obliquely incident seismic waves is significantly different from that of the vertical incidence.The integrated stress of the utility tunnel is mainly distributed in the corner of the tunnel and the upper and lower ends of the column.The change of the velocity structure of the layered soil has a significant effect on the seismic response of the utility tunnel.(2)Scattering of Plane P and SV waves by Half-Space Tunnel Lining Based on Viscous-Slip Interface Contact ModelBased on viscous-slip model,the contact state between tunnel lining and surrounding rock is simulated by using MATLAB programming software.The scattering problem of P and SV waves by tunnel lining in elastic half-space is solved by indirect boundary integral equation method.The magnification of surface displacement and the effect of dynamic stress concentration of lining are investigated in detail and profoundly.The results show that the stiffness coefficient and viscosity coefficient of contact slip boundary have great influence on the dynamic stress distribution of tunnel lining.When the slip stiffness is small,the effect of dynamic stress concentration in resonance frequency section is more significant;with the increase of viscosity coefficient,the amplitude of circumferential stress in lining decreasesgradually.In addition,the influence of stiffness coefficient and viscosity coefficient on dynamic response of tunnel lining is also controlled by incident frequency and angle.(3)Seismic Response Simulation of Underground Station Structure of Tianjin Z2 LineTaking the rail transit project of Tianjin Z2 Line as an example,on the basis of the above-mentioned research on soil stratification,soft and complex sites,the seismic performance,stress state and displacement response of the station structure and the dynamic interaction characteristics of the soil-station structure in the uneven soft soil site of Tianjin Binhai New Area under the action of basic intensity and large earthquakes were investigated.The simulation results can provide a basis for seismic design of underground subway structures on liquefaction foundation.The deformation of foundation soil of underground structure is the main cause of earthquake damage of underground structure.However,a large number of numerical simulation studies neglect the cohesion between soil layer and underground structure,resulting in the distortion of tangential and normal stress transmission between soil and structure in dynamic analysis.The change of geological conditions along the underground structure has a great influence on the earthquake resistance of underground structure.When passing through soft soil,the earthquake disaster caused by underground structure is more serious.