An estimated one million dollars was saved by installing a specially designed braced sheet piling system to support the foundation excavation of a 35-story building. An existing on-site structure required the 45-ft-deep, 265 x 270 ft. evcavation. Immediately after digging and shoring the first 140 x 270-ft. stage with a 3 levels of strutted sheet piles, and installing a strongback diaphragm wall at the site's mid-point, work was begun on a second adjoining stage. Simultaneously crews set lower level framing steel for the building in the first stage excavation. As concrete slabs for the buildings three basement floor levels were placed in the rising structural steel, they joined the foundation mat bracing against the diaphram wall. Thus the slabs took over lateral bracing loads as excavation for the second stage descended. Successive levels of first-stage pipe struts and waler were cut loose and pulled through holes in the sheet piling for reinstallation at the same levels in the new excavation alongside. Details are outlined of the multi-phase digging: foundation operations, foundation piling, predrilling through fill and old timber, sheet pile driving and bearing pile installation. The welding and jacking of pipe struts are also described. The foundation work had to overcome problems created by a water table at - 14 ft. Another project on a twin building is described in which the contractor braced the bulkhead with four levels of pipe struts diagonally placed in a diamond pattern to provide maximum working space in the center of the excavation. Maintaining a range for hauling equipment, the contractor excavated for 130 x 13 ft. center foundation mat. Bracing was done against the mat for successive balanced excavations and mat placements around the perimeter. Four levels of bracing were required because, on this site, excavated to its full dimensions, the installation started from near grade.

  • Corporate Authors:

    McGraw-Hill, Incorporated

    330 West 42nd Street
    New York, NY  United States  10036
  • Authors:
    • Drossell, M R
  • Publication Date: 1975-8

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Filing Info

  • Accession Number: 00127480
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 10 1976 12:00AM