AN EVALUATION OF DESIGN METHODS FOR DRILLED SHAFTS (IN FLORIDA LIMESTONE). VOLUME 2 OF 2. FINAL REPORT

The objectives of this research were to improve our understanding and design procedures of drilled shafts socketed in weathered Floridian limestones. A database of 24 instrumented drilled shaft load tests was collected, and various correlations between rock properties and engineering parameters evaluated. Data reduction of instrumentation (sister bars and telltales) was evaluated and a computer program prepared. Six design methodologies for rock socketed shafts were examined for capabilities in predicting capacity and settlement, as well as their required input parameters. The geological aspects of Floridian limestones were summarized. The results of the investigation showed that Florida limestones are quite varied and their properties are usually assessed by RQD, unconfined compression, and SPT N values, with the latter two being used for design. A correlation between unconfined compression and side friction shows some promise. Both telltales and sister bars perform satisfactorily; however, the former requires greater attention to detail and is more affected by temperature than the latter. The rock socket side friction t-z curves are nonlinear, strain hardening, with no post peak strength reduction, and exhibit failure deformations ranging from 0.015 in. to 2.0 in., but generally less than 0.2 in. The majority of drilled shafts designed in Florida rely only upon side resistance of the rock socket and overburden, and conservatively neglect tip resistance. Geologically, 18 different limestone formations exist within Florida.

• Corporate Authors:

  University of Florida, Gainesville

  Engineering and Industrial Experiment Station
  Gainesville, FL  United States  32611

  Florida Department of Transportation

  P.O. Box 1029
  Gainesville, FL  United States  32602

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Parra, F
  • Townsend, F C
  • McVay, M C
  • Martinez, R E
• Publication Date: 1990-7

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 294 p.

Subject/Index Terms

• TRT Terms: Computer programs; Design methods; Field studies; Forecasting; Friction; Geology; Limestone; Load tests; Settlement (Structures)
• Uncontrolled Terms: Capacity; Drilled shafts; Field data; Unconfined compression
• Subject Areas: Bridges and other structures; Design; Geotechnology; Highways; I24: Design of Bridges and Retaining Walls; I43: Rock Mechanics;

Filing Info

• Accession Number: 00611893
• Record Type: Publication
• Report/Paper Numbers: FL/DOT/RMC/0441-2933
• Contract Numbers: C-2933
• Files: TRIS, USDOT, STATEDOT
• Created Date: Aug 31 1991 12:00AM