The excavation for the 53-story reinforced concrete One Museum Park West building (OMPW) in Chicago was constructed using combined support systems. The building was supported by caissons and a perimeter wall formed by secant piles which transitioned to tangent piles below the bottom of the cut. After installing the perimeter wall and deep foundations for the building, the excavation for the reinforced concrete central core was supported by a circular cofferdam made of sheet piles and steel ring beams. This excavation was made using conventional bottom-up excavation techniques. The excavation for the rest of the building was made using a top-down method and was laterally braced with reinforced concrete floor slabs structurally connected to the secant pile walls and the reinforced concrete core. Field performance data during construction of the OMPW basements were collected with settlement points, inclinometers and strain gages installed in the concrete basement slabs. Significant settlements were observed adjacent to the excavation during wall and deep foundation installation, central core construction and top-down excavation. The influence of concrete material time-dependence of the floor slabs on the performance during top-down excavation is evaluated and a method for the separation of temperature-related strains from the excavation-induced strains in the concrete is described. The construction of the basements is simulated with a 3D numerical structural model to study the influence of the concrete material time-dependence of the floor slabs in the excavation-induced movements resulting from top-down construction. Computed strains in the floor slabs are compared with the observed performance data collected from the strain gages. For use in numerical simulation of the entire excavation process, hypoplasticity constitutive parameters for clays (HC model) at the element test level were calibrated with tests conducted on high quality block samples obtained from the excavation of Block 37 project in Chicago. They included oedometer tests, bender element measurements, and triaxial tests following different stress probes, and were further refined with seismic cone penetration results. The entire OMPW excavation is simulated with the calibrated parameters with a fully coupled-flow deformation, three-dimensional finite element model. Influence of the construction of secant pile walls, concrete material time-dependence, and nonlinear concrete behavior of the perimeter pile walls on the performance of the OMPW excavation is determined. Conclusions about top-down construction are drawn in light of the measured and simulated performance of the OMPW excavation.
Agregar etiquetas para Performance, instrumentation and numerical simulation of one museum park west excavation = Desempeño, instrumentación y modelación numérica de la excavación del edificio “One museum park west”