Dynamic Model Of Unsaturated Loess And It's Application To The Seismic Response Of Subway Station

The subway is one of the most effective methods to solve urban traffic congestion and pollution of the environment, used by many large cities. People generally considered that the subway as the underground structure has stronger anti-seismic capability. But Kobe earthquake and other earthqakes show that the subway may also occur severely damaged under the earthquake, and it is very difficult to repair. Subway station is the hub of metro operation. There are many equipments and persons. It will bring large economic and societal losses when it is destroyed. With the development of economy, the dimension of subway construction is extened increasingly. It is necessary and pressing to study on the response of the subway station under the earthquake. The study is usually in the saturated soil area, and it is a less in unsaturated soil area. On the basis of previous researches about the structure and unsaturation of unsaturated soils, this paper establishes the dynamic model of the unsaturated soils. The seismic response of the unsaturated soils field and the subway station in unsaturated soil area are analyzed by finite-infinite element coupling method with the establisded model. The main content of the paper including the followings five aspects:(1) The stress-strain of five kinds of water content unsaturated soil under three kinds of consolidtated pressures is studied through the soil of static triaxial shearing test. The effect of water content and consolidtated pressure to the strength and deformation is analyzed. The stress share ratio is defined to study the structure of unsaturated soil, the effect of two factors are analyzed. The stress-strain of three kinds of water content unsaturated soil is studied through the soil of dynamic triaxial shearing test. The damp and dynamic modul between water content are analyzed.(2) The dynamic model of reconstituted unsaturated soil is established based on the theory of bounding surface model. It contains the parameter of water water content in order to express unsaturated. The itact unsaturated soil's dynamic model is established based on model of reconstituted unsaturated soil by introducing the parameter of stress share ratio.(3) The programming steps of the unsaturated soil's dynamic model is given and the detailed numerical calculation formula is deduced. The programm of the model is writen by Fortran language on the platform of the finite element software ABAQUS. The tests of soil are modeled to validate the established models.(4) On the basis of the established unsaturated soil's model, the seismic response of the unsaturated soils field and the subway station in unsaturated soil area are analyzed by finite-infinite element coupling method. The effects of some factors, such as water content, soil structure, depth are analyzed.