Influence Analysis Of Tunnel Structure On Seismic Response Of Ground Considering Groundwater Conditions

With the continuous development of China's economy and the emergence of logistics express industry,the transportation system of many large cities has meet an unprecedented challenge.In order to alleviate the increasingly serious urban traffic pressure,many cities will be looking to the underground tunnel structure.After many years of development,now the subway has become the most important vehicle.At the same time,the research on the seismic effect of underground tunnel structure on the site has become an important subject at home and abroad,and it will provide useful reference value for underground engineering construction.This paper uses the finite element method and the following problems are studied :(1)A three-dimensional model of homogeneous soil and layered soil with a single tunnel is established,by selecting circular,rectangular and horseshoe shape cross sections tunnel to study the seismic response of tunnel section and groundwater on the site of different underground water level.The research shows that the influence of tunnel section on seismic response of site is different under different geological conditions;With the increase of groundwater depth,the seismic response of the ground surface is larger,and the seismic amplification effect of layered soil site is generally greater than that of homogeneous soil.(2)Considering the seismic response of the site under different groundwater levels,by establishing the parallel double tunnels with different spacing in the homogeneous soil and the layered soil site respectively,we can study the influence of tunnel spacing on the acceleration and displacement of the site and the influence of groundwater depth on stress of tunnel lining.Analysis shows that the magnitude of the tunnel spacing does not simply increase or decrease the seismic response if considering the geological conditions.The tunnel lining is also affected by groundwater in the seismic response,and the maximum stress position changes obviously due to liquefaction.(3)Through the establishment of single-tunnel and double-tunnel finite element models respectively,the influence of pore-water pressure on tunnel structure is studied.Analysis shows that the single tunnel can greatly amplify the pore water pressure.In the case of double tunnels,the peak pore water pressure between the tunnels is slightly larger than the outside of the tunnel.