By: Mike Muchard, P'E'

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Drilled Shaft Quality Assurance Testing

• By Mike Muchard, P.E.
• Applied Foundation Testing, Inc.

AFT
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Drilled Shaft Quality Assurance Test Methods

• Before
• Good Construction / Inspection Practice
• After
• Crosshole Sonic Logging (CSL)
• Singlehole Sonic Logging (SSL)
• Crosshole Tomography
• Sonic Echo (SE)
• Gamma-Gamma

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QA Methods During Construction
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Drilled Shaft Quality Assurance

• Most Common Construction
• Wet Method
• Temp Casing Method
• Slurry Management
• Mineral Attapulgite and Bentonite
• Slurry Testing Density, Viscosity, PH, Sand
• Bottom Cleanliness
• Tremie
• On bottom
• No Breach
• 12 hour Time lime open excavation
• Concrete slump min 4 - 7 to 9 Best

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ShaftInspectionDevice(SID)
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Passing Criteria

• 1 over the Base for Misc. Drilled Shafts

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Calibrate Feel of Weighted Tape
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Use Submersible Pump andFlat Bottom Cleanout
BucketTo Get Better Cleanliness
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Post ConstructionMethods
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Crosshole Sonic Logging (CSL)And Derivatives
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CSL Tubes
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CSL Tube Prep

• Steel Tubes Preferred over PVC for CSL
• PVC De-bonds Quicker
• Tubes Mounted on Inside of Cage
• Typically 1 Tube per Foot of Diameter
• Tubes Capped at Top and Bottom
• Filled With Water Before Pouring Concrete

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Good CSL Result
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Concrete Velocity Based Criteria
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Crosshole Sonic Logging Case History
Slightly Delayed Arrival Time
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Tomography to Better Define a Low Velocity Zone
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Crosshole Sonic Logging Case History

• Remediation Required

Major Loss Of Signal
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Soft Toe CSL Remedial Grouting Shaft Toe
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Crosshole Sonic Logging Case History

• PVC Tube De-Bonding - 2 day, 4 day and 11 day
  Tests

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CSL Limitations

• Can Only Evaluate Inside of Cage
• Dependent on Bonding Condition of Tubes
• Dependent on Engineering Interpretation

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Gamma- Gamma Logging
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Sonic Echo / Impulse Response
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Good Result
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Shows Enlarged Bulge Near Toe (Still Good)
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Pulse Echo Limitations

• Can Be Inconclusive.
• Unable to Detect Flaws Smaller Than 25 of Cross
  Section
• Not Able to Detect Soft Bottom
• Heavily Dependent on Test Operator

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Good Construction Practice is Solution Thank
You