Dynamic soil-structure interaction of underground structures adjacent to tall buildings

Underground structures are commonly constructed near existing or new tall buildings in dense urban areas. During earthquake shaking, tall buildings generate base shear that is carried by the building foundation and surrounding soils. This base shear may be transmitted to adjacent underground structures, increasing the seismic demand on the underground structure. In the current practice of seismic design of underground structures, Engineers often rely on numerical models to evaluate the seismic response of a tunnel in dense urban area. However, these numerical models generally have not been validated against the field data because of the lack of experimental data. Therefore, the numerical model used in the analysis might be less reliable. Additionally, engineers often use simplified procedures in evaluating an underground structure under seismic loading that do not consider the soil-structure interaction among the superstructure, underground structure, and the surrounding soils in the system. These limitations in the seismic design of underground structures adjacent to tall buildings can lead to underestimation or overestimation of the seismic demands imposed on the underground structure. Therefore, the present study was conducted by combining the results from dynamic centrifuge tests and numerical simulations to evaluate the impact of highly idealized adjacent tall buildings on the seismic response of underground structures. The study was started by developing calibrated numerical models by comparing the numerical simulations with the corresponding measurements from the centrifuge tests. The numerical model can reproduce the seismic behavior observed in the centrifuge including the additional loading demands imposed by adjacent building on underground structures. A large-scale parametric study using three-dimensional (3-D) nonlinear finite element analysis with more realistic soil-structure-underground structure (SSUS) representation was then performed to evaluate the impact of variability in the SSUS system on the seismic response of underground structures. The effects of different building heights, building foundations, underground structure configurations, and soil profiles are evaluated using a suite of ground motions. These configurations represent the range of conditions that are likely to be present in dense urban environments. The results show that (a) as the adjacent building became taller and hence the base shear increased, greater dynamic earth pressures were transmitted to the underground structure, (b) the dynamic earth pressures were reduced with increased building-to-underground-structure distance, and (c) the racking displacements of underground structures were strongly dependent on building foundation and underground structure configurations such as basement depth, pile length, and the depth of the underground structure. For design purposes, these interactions need to be considered by modeling a realistic building and underground structure representation in a SSUS system to evaluate the added demands that a given building will impose on underground structures including cut-and-cover boxes and bored tunnels.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste