The interaction of structural loads and rock/soil conditions in South Florida is not well understood. This note is a step toward quantifying how the South Florida limestones and soils respond to large area loads. The construction of a regional sewage treatment facility in Dade County, Florida, involved preloading a site underlain with loose sands and soft limestones. The soils at this site along with the settlements anticipated and produced by the preloads are examined in this note. The purpose of the preload was to measure the magnitude of possible settlement and to induce settlements prior to construction. At the same time, the settlement was calculated by summing the expected deformation in each layer, which in turn was calculated by multiplying the stress in each layer by the thickness of the layer and then dividing the result by the modulus of compressibility. Generally, the calculated settlements were higher than those measured in the field, perhaps because the soil modulus correlation in sand is not absolute, the sand stratum thickness beneath the oolitic limestone is quite variable, and the average subsurface conditions at the settlement plate location may not be representative of the soil conditions at the boring ocations, i.e., erratic soil conditons occur over short distances. Incomplete muck removal may account for those few instances where the field measurement were higher than predicted. The total settlements were from 1.4 -5.1 inches (36-130mm) at the site. After removal of the preload, rebound in almost all cases was less than 0.5 inch (13mm). The data indicates that the magnitude of total settlement is related to the thickness and density of the sand strata underlying the oolitic limestone.

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Filing Info

  • Accession Number: 00196151
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 14621 Proceeding
  • Files: TRIS
  • Created Date: Oct 17 1979 12:00AM