Roberts, Don V.
Partner, Dames and Moore, Los Angeles, Calif.
Darragh, Robert D.
Associate, Dames and Moore, San Francisco, Calif.
Pages: 20 Published: Jan 1962
Previously published data on allowable building settlements have not included cases where the settlements were due to the fill loads. In this paper, comparisons have been made between calculated and observed areal fill settlements of 1 to 4 ft at the San Francisco Airport. The effects of these settlements on buildings supported on pile foundations and spread footings are reported for three aircraft hangars and one terminal building. These data indicate that the Terzaghi theory of consolidation permits reasonably accurate settlement calculations for the consolidation of a postglacial marine clay (bay mud) under fill loads. Differences in fill thickness resulting from shear failures of the soft bay mud during site grading can cause serious problems in building and site behavior. Surcharge fills are effective in reducing postconstruction settlements and hangar foundation costs in areas of shallow bay mud. Light steel frame buildings supported on spread footings can withstand total settlements of 1 ft and differential settlements of several inches. Pile foundations must be designed for the negative friction forces imposed by subsiding soils if settlements are to be controlled.
Paper ID: STP47042S