Seismic analysis of the soil–structure interaction for a high rise building adjacent to deep excavation

• Numerical analyses of the building–excavation interaction and fixed–base models.
• Reduction of 35% in the interaction models' base shear compared to the fixed–base model.
• Reduction of 28% in the story drift ratio, while considering the excavation in modeling.
• Exerting impacts on the retaining wall and building by structure's modeling type.
• Surveying criteria for estimating the damage of a building adjacent to excavation.

Soil–structure interaction is referred to the process in which the soil response is influenced by the structure motion while the latter is influenced by the soil motion. It is of note that the excavation adjacent to the buildings can intensify the effects of soil–structure interaction. In the current research, the soil–structure interaction model and the building–excavation interaction model along with the fixed–base structure model were analyzed on the basis of finite difference method using FLAC2D, which is capable of analyzing the soil–structure interaction issues. Furthermore, the modified Mohr–Coulomb constitutive model was employed for the soil medium, allowing the implementation of dependency of stiffness on stress as well as the materials unloading behavior by means of the powerful programming language FISH (short for FLACish). Validation of the numerical model was accomplished based on the data extracted from the Tiltmeter installed on one of the columns of the building adjacent to the excavation and the Load Cells placed on the anchors of the excavation wall. The results illustrated that due to the high stiffness and rigidity of the retaining structure system, modeling of the building adjacent to the excavation, whether as surcharge or structural frame, would only influence the settlement profile of the building foundation under static conditions. On the other hand, in the seismic analysis, the type of modeling of the building adjacent to the excavation exerted a remarkable impact on the pile deformation, the bending moment of the pile, the condition for connection of the anchors and soil, the criteria for estimating the probable damage of the structure adjacent to the excavation, and the permanent settlement profile.

Schematics of Model 1 (soil stratigraphy), Model 2 (without surcharge), Model 3 (soil–structure interaction), Model 4 (building–excavation interaction), Model 5 (surcharge) and Model 6 (fixed–base) in FLAC2D:Figure optionsDownload as PowerPoint slide