Field Performance of Structural Slurry Wall

Geotechnical instrumentation for both routine monitoring and research was conducted during construction of the new Harvard Square Station, part of expansion of a rapid transit line in metropolitan Boston. The cut‐and‐cover structure was designed with slurry walls (cast‐in‐place concrete diaphragm walls) that were used both for initial excavation support and as final structural walls. The purpose of the study was to develop a better understanding of slurry walls systems that will benefit future design and construction of slurry walls as permanent structures. In conjunction with analytical studies, the field measurements provided better understanding of slurry wall behavior both during construction and the long term. The field measurements summarized in this report focused on lateral movements, bending in the wall as measured by strain gauges, and settlement of the wall and adjacent structures. Field measurements showed movements to be small, and bending in the stiff wall to be less than design values. Design recommendations are given.