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March 23, 2001 Lee Kennedy Co., Inc. uses Geo Jet Technology to Maximize Efficiency and Minimize Disturbance When Simmons College hired Lee Kennedy Co. to construct its new building at One Palace Road in the Fenway, two major issues needed to be resolved: how best to build underground parking below the water table, and how to do so without disturbing the Museum located across the street from the project site. The method needed to be reliable and economically feasible. Through a rigorous preconstruction process, Lee Kennedy Co investigated several methods and determined that the Geo Jet® earth retention wall system was the most appropriate means for completing the complex project. The Geo Jet system has minimal vibration and creates a temporary impermeable earth-retentive wall that allows for the excavation and construction of conventional footings and foundation installation. The Geo Jet process, developed in Italy, has been used primarily on the "Big Dig" and only a handful of times for buildings in the United States. Geo Jet is a method in which the soil is augured, while at the same injected with grout that mixes with the soil and creates a column in the ground. Grout can be injected into the soil at pressures up to 5000 psi. A total of 400 30-inch holes were augured around all four sides of the One Palace Road site. The holes were 30 inches wide and overlapped by 6 inches on each side. "Primary holes" were augured first and alternated every other hole until the grout set. Drilling the holes consecutively would have damaged the previous hole, therefore, holes were drilled in this "every-other" fashion. "Secondary holes" were augured in the same manner between the primary holes with the only difference being that an H pile was placed in each secondary hole. A variety of H pile sizes were engineered for this particular project. The heaviest are along Palace Road where the piles are w24 x 104 x 58' long. The soil mix wall of One Palace Road is 54.5' in length at its lowest depth.
Completion of the soil mix wall allows for tiebacks to be installed and then approximately 48,000 yards of material will be excavated from within the footprint of the garage. This will occur within a four-month schedule. Placement of all the concrete within the garage is expected to be completed in another four months. In order to fully control and manage any vibration to surrounding structures-two of which are on wood pile construction-two seismographs were installed in the Isabella Stewart Gardner Museum to monitor any movements. Additionally, water table wells within the museum are checked daily. In addition to the three under ground levels, the new building will contain four levels of academic, administrative and instructional space. The 60,000 square foot building will house the Graduate School of Social Work, the Graduate School of Library Information Sciences and technology and student services. Marc Buchan and Don Cook are the project manager and superintendent, respectively, for One Palace Road. In addition to the renovations they recently performed to South and Dix Halls at Simmons College, Marc has worked on projects that include the historic renovation of the Boston Public Library McKim Building and the New England College of Optometry. Don's project experience includes the exterior renovation of the Isabella Stewart Gardner Museum and the renovation/addition at International Cargo Port. << back
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Performing
construction with as little disturbance as possible to neighboring
properties is always the goal of any construction project. It is
even more so when one of the abutters is the Isabella Stewart Gardner
Museum, which houses 2,500 renowned artworks that date back many
centuries. Even more challenging is building three levels of underground
parking--two of which are below the water table--across the street
from the museum.
The
drill rig is equipped with an on-board computer that stores data
for every hole augured. The computer monitors the entire process
to ensure the proper density of the soil-cement mixture is met.
The data contains such information as drilling rate, grout pressure,
grout volume and grout flow. An average augured hole at the One
Palace Road site contains approximately 900 gallons of grout. |
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