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 Monitoring Rock Drilling Rock Strength Shaft Side Shear Torque Drilling

  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.).
  
  
• Format:
  PDF
• Funding:
  FDOT Contract No. BDV31-977-20;UF Contract No. 00
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:2ad085555bf770bdfec4ff896e86a7cb32fac608fb6255231378da15a51f4938b4f2e24d67f62f21fbcb957960ec27612df744b7e90374e82298c56f15981a21
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/30996/dot_30996_DS1.pdf
• File Type:
  [PDF - 11.50 MB ]