The Research Of Several Factors About The Soil-structure Dynamic Response Under Earthquake Action

In this thesis, the finite difference software FLAC3D and finite element analysis software Midas gts regard as a platform, through the Midas gts establish a numerical model then imported into FLAC3D to analysis the seismic response of underground structures in a layed foundation, in which the property of the soil is diffrernt,as well as the different distribution of layered soil caused underground structures seismic effects. Finally, the calculation method of soil displacement that the soil and understructure dynamic calculation involved are discussed, the main research achievements include the following three aspects:The first part of the paper, Guo Zhuangzi subway station in Beijing subway line14was taken as a calculation model to analysis the structure in between two layers of the soil, when the soil parameters (shear modulus) change and to study the law of the seismic response of underground structures.By calculating Mises stress and horizontal displacement of the key points in the structural model, it found that the maximum Mises stress and horizontal displacement of the understructure occurred at G1/G2was about0.1, which means that in real engineering conditions, when the soil structure is located on the soil which the above is soft while subsoil is harder,the topsoil and subsoil shear modulus ratio is about0.1, then risk the structure suffered is greater.The second part of the paper by establishing analysis model under different geological conditions and setting Hardin/Drnevich damping to consider reasonable description the hysteresis curves and hysteresis loops of the soil under dynamic action, and dynamic interaction seismic response of underground structures analyzed due to the different nature of the foundation soil.It come to the following conclusions:1) Different soil distribution has a significant impacl on the seismic response of underground structures, In multi-geological condition, underground structures in soft soil under horizontal seismic response was significantly greater than other soil profile.2) In contrast, underground structures in the hard soil or underground structures in a better stratum and a weak harrier layer, At this point the structures in the relatively safe under earthquake.3) Distribution on the same soil engineering geology, the location of underground structures should be chosen uniform soil changes with depth, or have better holding power engineering geological layers.The third part of the paper by utilizing "Urban Rail Transit seismic design specifications"(draft) and Edushake program to calculate the level displacement of the layered foundation, and New Rail Transit Line of the Shijiazhuang Zhengding reserved engineering geology as calculation model, Analysis the relationship between peak displacement and depth of soil by different calculation methods. Differences arising between various methods is described and take reference recommendations to the "Urban Rail Transit Seismic Design Code"(draft) and engineering design displacement of the soil.1) Proposal when calculating soil displacement one-dimensional space equivalent linear (or finite element) by the "urban rail transit Seismic Design Code"(draft) should be increased for different engineering Geology how to select the views of seismic waves or provide multiple sets of reference values apply to different venues seismic wave data.2) For the design of the application, the proposed site should be used for engineering seismic data sets of numerical calculations based on engineering geological safety assessment, and then compared with the "urban rail transit seismic design specifications" in the recommended formula, derived its the maximum value as a reference design.