DYWIDAG Systems Stabilize Excavation in Baltimore's Inner Harbor
In the 1970’s, the harbor area was rediscovered as an economic and cultural center of the city, and new buildings were constructed in the area. Construction activities continue to be strong – especially so in Harbor East. DYWIDAG is making a significant contribution to one of these projects: the construction of the high rise Four Seasons Hotel.
Context
The city of Baltimore, with a population of approximately 641,000, is the largest city in the state of Maryland and one of the most important seaports in the US. The city is an important industrial and commercial center as well as a significant location for research and development in pharmaceutics and medicine.
Due to its many historic buildings, Baltimore also attracts numerous tourists. The Inner Harbor, the city’s inland port, is especially popular with visitors. The harbor was a working port from the 17th century up to the mid 20th century.
Since then, an increasing number of museums, shops, residential buildings, restaurants and hotels have emerged in Baltimore’s Inner Harbor.
Since the new building is a mere 6m away from the port basin, the bathtub-like excavation for the fourstory parking garage, which is up to 18m deep in places, had to be stabilized by an 8,800m² tieback diaphragm wall. The excavation’s bathtub structure is supported laterally by the concrete slabs that form the parking garage floor.
Solution
DYWIDAG supplied a total of 537 temporary DYWIDAG Strand Anchors with 9-26 strands each in lengths of approximately 27 to 30m. In addition, DYWIDAG also supplied 65mm Gr 150 DYWIDAG bars and couplers for 36 temporary micropiles in lengths of 20,5m. These micropiles were later removed between the floors.
The work was made difficult by extremely differing soil conditions and high hydrostatic pressures. Due to the varying pressures, four different levels of tiebacks were used. In addition, DYWIDAG Strand Anchors were adapted individually to meet expected levels of pressure. In the lowest anchor row, strand anchors with up to 26 strands were successfully installed and post-tensioned. The completion of the new Four Seasons Hotel is planned for summer 2010.
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