Research On The Influence Of Different Soil Distribution On Underground Structure Under Seismic Load

After entering the 21st century,the rapid development of urbanization in our country,urban population increased year by year,which makes the urban traffic congestion problems highlighted increasingly,to travel life traffic jams.The key to solve the problem of urban traffic congestion is to reasonable development and utilization of urban underground space,including the development of subway project are beneficial to ease traffic pressure on the ground,solve the problem of urban traffic congestion,improve the efficiency of daily travel.However,in recent years,China’s earthquake disasters have occurred frequently,and the subway station,as a public transportation area with dense population,it has received widespread attention for its seismic problems.There are many factors that can influence of subway station seismic,such as the size of the structure of the buried depth,structure,characteristic parameters of seismic wave and the effect,etc.,which subway station of soil properties is one of the important factors that affect the structural seismic performance,especially when the structure in a variety of properties of different foundation soil.Therefore,it is of great practical significance to study the seismic response of different soil layers to underground structures.Taking a subway tunnel as an example,the tunnel section is a single-layer double-span box structure with a discontinuous column in the middle.The column spacing is 4m.The soil-structure model is established by the finite element software UC-WCOMD.The value.range of foundation soil is 3 times of station height and width respectively.The artificial boundary is chosen to be close to the actual viscoelastic boundary conditions.Kobe seismic waves of Japan,which are input in different directions to the overall model are selected,Dynamic response analysis,the influence of different soil layers on the underground structure is discussed.The analysis results can provide reference for the actual engineering design.The main research results of this paper are as follows:(1)The influence of soft soil layer distribution on the dynamic response of subway tunnel is different.When the soft soil layer is located at the top of structure roof,the upper end of the structure column shear failure occurs.When the weak soil layer distributes in the middle of the structure side wall,the tensile and shear failure occurs at the lower end of the column.When the weak soil layer is located at the lower part of the structural bottom plate,severe damage occurs to some structural units but no damage occurs.By analyzing the simulation results,it can be concluded that the influence of weak soil layer on seismic waves has a weakening effect.When the subway tunnel has a better holding layer and the soft soil layer is located at the bottom,the structure is not likely to be destroyed under the earthquake.(2)Under different directions,the dynamic response and structural damage of Kobe seismic wave show different behavior.Under the action of NS + UD seismic wave,the instability of the structure is more and the damage of some component elements is larger.The seismic wave action in the direction of EW + UD Under the structure damage is less,some components damage less.In the Kobe seismic wave,the influence of NS direction on the structure is greater than that of the EW direction.The weak parts of the metro station are mainly concentrated at the two ends of the center pillar,the combination of the side wall and the roof and floor,and should be taken as the key part in the design and construction.(3)The influence of the distribution of different soil layers on the seismic response of the subway tunnel is different.When the soil layer is less and evenly distributed around the tunnel,the dynamic response of the structure under earthquake is more obvious and intuitive.When the soil layer is more and more complex around the tunnel,the parameters and distribution of the soil layer are the important factors that affect the seismic performance of the structure.When locating and selecting buried depth of underground structures,we should try to avoid the soil with poor soil quality around the structure,and choose the best geological conditions for the soil layer to vary uniformly with the depth and the bearing stratum.