Publication Abstract

Proceedings of the 30th Annual Conference on Deep Foundations, 2005, Chicago, Illinois, USA, (DFI)

Design and Construction of Specialty Foundation for the Historic Virginia State Capitol Building
Robert S. Thomas, Bernard M. Tarralle, Nasser Massoudi

The Commonwealth of Virginia is restoring and expanding its Capitol of great historic significance. Designed by Thomas Jefferson in 1785, it is the second oldest Capitol building in the United States. The building expansion required excavations immediately adjacent to its South Portico. The building, which rests on shallow brick footings, is very sensitive to any disturbance caused by construction and excavation. A comprehensive and secure plan of operations was devised by the design team to ensure that this national monument remains unharmed by the new construction. Various construction techniques were implemented to satisfy the strict movement goal of 0.25 inch and distortion of L/2000. They consisted of jet grout columns to stabilize the upper soils, compensation grouting for future foundation leveling, a tied-back reinforced concrete diaphragm wall for excavation retention and foundations, and real-time instrumentation for monitoring. This paper describes the design approach for the retention system, providing information on the various construction phases and techniques, and reports on the movements recorded by the real-time monitoring system during the course of the project. At the time of this manuscript preparation, and the deep excavation complete to final grade, the results that the extremely restrictive building movement criteria have been met. The success can be credited to detailed design, close cooperation among the project team, prudent construction methods, and real-time monitoring.

 article #1278; publication #72 (AM-2005)