Seismic performance of underground structures based on realistic soil and structural model

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The research aims to understand the accuracy and limitations of commonly used numerical modelling methods for seismic soil-structure-interaction (SSI) analysis of underground structures. To accurately simulate the seismic SSI effect on underground structures, it is necessary to model both soil and structures with realistic numerical elements. Especially, if cracks or local failure develops in the underground structure, the current numerical assessment method based on idealized elastic system is not expected to be accurate. In current design and performance assessment practice, the seismic SSI of underground structure is accounted for by using a very simplified approach which is based on sweeping assumptions on linear-elastic soil-structure system. The proposed research aims to investigate the seismic performance of underground structures based on realistic soil and structural model. The main goal is 1) to evaluate the accuracy of the traditional assessment methods in comparison with a numerical model with accurate representation of soil and structure, and 2) to evaluate the influence of nearby structure on the seismic demand on underground structure. The scope of the study is limited to an idealized subway station subjected to ground shaking. The numerical model will be built upon a distributed simulation framework which allows different analytical models to be integrated within one simulation. Taking the advantage of this advanced modelling technique, various factors influencing the seismic performance of the structure will be investigated. Numerical results will be compared with the closed form solutions to further address the limitations of the simplified methods that are being used in practice.