Design and Performance of a Temporary Concrete Diaphragm Wall Excavation Support System in South Boston, Massachusetts

摘要

This paper discusses the design, analysis, and performance of a reinforced concrete diaphragm "slurry" wall temporary excavation support system in South Boston, Massachusetts. The excavation support system was required for construction of two deep below-grade parking garages transected by an existing underground transit tunnel. The excavation was approximately 8.8 m (29 ft) deep for one garage and approximately 14.3 m (47 ft) deep for the other. The excavations were supported with a combination of internal and external bracing. A PL AXIS 2D finite element model using the Mohr-Coulomb constitutive model for soil was used to perform staged construction analyses pre-construction. The model was calibrated post-construction using the hardening soil constitutive model based on field measured displacements from inclinometers. The calibrated model indicated that the hardening soil model provided better agreement with the actual slurry wall displacements and highlighted the sensitivity of the Boston blue clay parameters in the model.