One Lincoln Street Arched Slurry Wall

One Lincoln Street is one of the most recent buildings constructed in downtown Boston. Its structure consists of a 36-story high-rise building directly connected to a 7-story low-rise building. Its substructure has five levels of underground parking garage to accommodate 900 cars in a city where prime real estate is becoming scarce. The excavation for the underground parking garage was supported by reinforced concrete slurry walls, which also serve as the substructure’s permanent walls. The stiffness of the slurry walls, together with the strut and tieback bracing system, minimized movement during excavation, which occurred in close proximity to existing buildings. Of particular interest is the northwest corner of the excavation, which was supported by an arched slurry wall, possessing a shape in plan of a quadrant of a circle with a radius of 50 feet. This paper presents key aspects of the analysis, design, construction and performance of the arched slurry wall. While the other slurry walls in the project were designed to support the 59 foot deep excavation with two levels of bracing, a remarkable feat by itself, the 3 foot thick arched slurry wall was analyzed, designed and constructed to support the excavation with no bracing. The analysis consisted of two-dimensional finite element models, modified to include the effects of three-dimensional arch action. Predicted lateral movement of the wall was minimal, having minor impact to adjacent structures, and measured inclinometer readings favorably support the predicted movements.