Drilled Shaft Load Testing - Pages · • AASHTO Guidelines for Drilled Shafts in Rock provided...
29
Transcript of Drilled Shaft Load Testing - Pages · • AASHTO Guidelines for Drilled Shafts in Rock provided...
Drilled Shaft Load Testing
Ironton-Russell Bridge over the Ohio
River
ODOT OGE Workshop
Eric Kistner
May 7, 2013
Presentation Outline
• Project Background
• Drilled Shaft Capacity Estimates
• Test Planning and Preparation
• Osterberg Cell Test Results
Project Background
• Existing Bridge Constructed in 1922
• Replacement under construction
approximately 0.45 miles downstream of
existing bridge
• Owner – State of Ohio
• Designer - URS Corporation
• Geotechnical Engineer - Stantec
• Contractor – Brayman Construction Corp.
• Construction Inspection/Engineering - Figg
• Load Testing – LoadTest, EL Robinson
Project Background
Project Background
Rendering by URS
Drilled Shaft Capacity Estimates Proof Core – Test Shaft 1
• Ignore any capacity gained from
overburden soils
• Ignore capacity gained from coal/soft shale
horizon
• Estimate nominal unit side and base
resistance for the weathered and
unweathered sandstone bedrock
• Used combined shaft and base resistances
for design of drilled shafts
Drilled Shaft Capacity Estimates General Assumptions
Drilled Shaft Capacity Estimates AASHTO Guidelines – Side Resistance
Drilled Shaft Capacity Estimates AASHTO Guidelines – Tip Resistance
Drilled Shaft Capacity Estimates
Assumptions for Side Resistance
Structure Component
Bedrock Horizon Top of Horizon Elevation (feet)
Unconfined Compressive Strength (ksf)
Rock Mass Deformation
(Em/Ei)
Reduction Factor to
Account for Jointing (αE)
Pier 3 Weathered Sandstone
475 293 0.1 0.55
Pier 3 Unweathered
Sandstone 467 879 0.6 0.8
Pier 3 Coal/Claystone 457 -- -- --
Pier 3 Unweathered
Sandstone 451 879 0.6 0.8
Pier 4 Weathered Sandstone
475 293 0.1 0.55
Pier 4 Unweathered
Sandstone 467 879 0.1 0.55
Pier 4 Coal/Claystone 458 -- -- --
Pier 4 Unweathered
Sandstone 451 879 0.1 0.55
Drilled Shaft Capacity Estimates
Assumptions for Base Resistance
Structure Component
Bedrock Horizon Top of Horizon Elevation (feet)
Rock Type Rock Mass
Quality m, s
Pier 3 Weathered Sandstone
475 -- -- --
Pier 3 Unweathered
Sandstone 467 -- -- --
Pier 3 Coal/Claystone 457 -- -- --
Pier 3 Unweathered
Sandstone 451 C (Arenaceous) Good
1.231, 0.00293
Pier 4 Weathered Sandstone
475 -- -- --
Pier 4 Unweathered
Sandstone 467 -- -- --
Pier 4 Coal/Claystone 458 -- -- --
Pier 4 Unweathered
Sandstone 451 C (Arenaceous) Good
1.231, 0.00293
Drilled Shaft Capacity Estimates
Estimated Ultimate Axial Capacities for River Towers
Structure Component
Bedrock Horizon Top of Horizon Elevation (feet)
Unconfined Compressive Strength (ksf)
Side Resistance
(ksf)
Base Resistance
(ksf)
Pier 3 Weathered Sandstone 475 293 9 --
Pier 3 Unweathered Sandstone 467 879 22 --
Pier 3 Coal/Claystone 457 -- -- --
Pier 3 Unweathered Sandstone 451 879 22 279
Pier 4 Weathered Sandstone 475 293 9 --
Pier 4 Unweathered Sandstone 467 879 15 --
Pier 4 Coal/Claystone 458 -- -- --
Pier 4 Unweathered Sandstone 451 879 15 279
Test Planning and Preparation
• Two test shafts (left in place to support
false-work)
• Osterberg method – test axial capacity
• Lateral load test – test behavior of the shafts
under lateral loading
• Used to confirm assumed bedrock
parameters
• Used to make design adjustments if
necessary
• Group effects not tested
Test Planning and Preparation
Test Planning and Preparation
Test Planning and Preparation
Test Planning and Preparation
Osterberg Cell Test
Test Planning and Preparation
Test Planning and Preparation
Test Planning and Preparation
Osterberg Cell Test
= 279 ksf x π(4’)2
11,750 kips = 18.7 ksf
25’π(8’)
Hold Time = 8 minutes
Test stopped due to
plunging in upward
direction at 16,000 kips
Osterberg Cell Test
Osterberg Cell Test
Weathered Sandstone
Unweathered Sandstone
Osterberg Cell Test
Results of Test vs. Recommended Values
Based on 0.25 inches of deflection
Bedrock Horizon
Stantec Geotechnical Report, March 2011
Osterberg Cell Load Test, July 2012
Unit End Bearing (ksf)
Unit Side Resistance (ksf)
Unit End Bearing (ksf)
Unit Side Resistance (ksf)
Weathered Sandstone
-- 9 -- 12
Unweathered Sandstone
279 15 to 22 307 23
Conclusions
• Design changes not necessary
• AASHTO Guidelines for Drilled Shafts in
Rock provided reasonable results
• Cost of Osterberg Cell Test = $575,000
February 2012 – Notice to Proceed
October 2015 – Scheduled Opening to Traffic
$81.2 Million Construction Cost
Construction Status
March 2013
Construction Status
March 2013
Construction Status
March 2013
