Drilled shaft resistance based on diameter, torque and crowd (drilling resistance vs. Rock strength) phase II : final report.

Details

• Creators:
  McVay, Michael C. ; Rodgers, Michael O.
• Corporate Creators:
  University of Florida. Dept. of Civil and Coastal Engineering
• Corporate Contributors:
  Florida. Department of Transportation
• Subject/TRT Terms:
  • Compressive strength
  • Evaluation
  • Field tests
  • Laboratory tests
  • Limestone
  • Load tests
  • Rock drilling
  • Torque Drilling
  • monitoring
  • rock strength
  More +
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States;Florida
• Edition:
  Final report
• Corporate Publisher:
  Florida. Department of Transportation. Research Center
• Abstract:
  The research focused on evaluation of Florida limestone’s unconfined compressive strength, qu, through ; drilling parameters – crowd, torque, penetration rate, rotational speed, and bit diameter – in both the ; laboratory and field for assessing a shaft’s side shear. Synthetic homogeneous limestone blocks of ; various strengths were cast in the laboratory and allowed to cure for 14 days; The blocks were then ; drilled with rock augers of two different diameters at multiple penetration rates and drilling rotational ; speeds. Both crowd and torque were measured in real time. Estimation of rock strength, qu from drilling ; relationships developed by Karasawa (2002a) and Teale (1965) were evaluated. It was found that ; Teale’s specific energy approach could estimate rock strength, qu using the multiple diameter drill bits ; expected in field drilled shaft construction. ; In the field, shaft installation was monitored (crowd, torque, penetration rate, etc.) at three sites (Little ; River, Overland, and Kanapaha) from which rock strength, qu was estimated along with shaft side shear. ; For side shear, FDOT’s design equation in limestone was used with split tension strength initially ; estimated from qt/qu ratio established by field cores; subsequently, Johnston’s qu vs. qt/qu relationship ; was used. The estimated unit skin friction in multiple rock formations and segments was compared by ; instrumented segment during Osterberg, Statnamic, and top-down static load testing. The mean bias ; (measured/predicted) unit side shear in limestone was 1.00, and the coefficient of variation, CV, was ; 0.07. The results suggest that estimating rock strength and shaft side shear using drilling parameters is ; viable, especially considering the currently available rig monitoring equipment (Jean Lutz, Bauer, etc.).
  More +
• Format:
  PDF
• Funding:
  FDOT Contract No. BDV31-977-20;UF Contract No. 00
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/30996/dot_30996_DS1.pdf
• File Type:
  [PDF - 11.50 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:2ad085555bf770bdfec4ff896e86a7cb32fac608fb6255231378da15a51f4938b4f2e24d67f62f21fbcb957960ec27612df744b7e90374e82298c56f15981a21