NEW YORK'S GLACIAL LAKE FORMATION

In response to the suggestion that the differential settlements between the center and corner of some buildings be taken into account when determining tolerable settlements of buildings, it is noted that no evidence of cracks or other distress due to settlement has been observed, even in the case of a building when the differntial was 1.5 inches (38 mm) after nine years, the largest observed. This is due to the fact that 75-85 percent of the primary settlement occurred during construction. Variables important in determining the settlements to be anticipated include bearing values derived from plate bearing and trial tests assuming relationships for isotropic conditions, estimated preconsolidation load, and, in the case of tailer buildings, stability analyses against wind forces. The choice of what building supports to use was dictated primarily by economic considerations: short piles rather than spread footings or mats in the case of the granular supporting layer existing well below ground water (thus eliminating the need for dewatering) and mats rather than spread footings in the case of building loads being high enough to require nearly contiguous footing. Although excavation was only carried down to the sand above the varied silt layer, dewatering was sometimes necessary. This requires careful determination of well-point depth and spacing, proper sanding-in of points, and allowance of adequate time to accomplish the drawdown. In response to the suggestions that more sophisticated methods of estimating settlements would yield better results and that the "antiquated" methods actually used might not always yield as good results as they did in this instance, it is noted that these sophisticated methods when applied to some of the writer's cases actually yielded less accurate results and hence are probably not applicable in those instances.

  • Availability:
  • Supplemental Notes:
    • Discussion of Proceeding Paper 12218 by James D. Parsons, June, 1976.
  • Corporate Authors:

    American Society of Civil Engineers

    345 East 47th Street
    New York, NY  USA  10017-2398
  • Discussers:
    • Parsons, J D
  • Publication Date: 1978-9

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00183211
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 13999
  • Files: TRIS
  • Created Date: Nov 14 1978 12:00AM