Evaluating Wick Drain Performance in Virginia Soils

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Evaluating Wick Drain Performance in Virginia
Soils

• Susan E. Burns
• University of Virginia

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Graduate and Undergraduate Research Assistants

• Matthew J. ClineM.S. Civil Engineering, 2002

• J. Matthew Wright
• B.S. Civil Engineering, 2001

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Prefabricated Vertical Drain Study

• Literature Review / Soil Characterization
• Damage Testing (complete June 01)
• 90 Crimp
• Lateral Pressure Test (start May 01)
• Consolidation (start June 01)

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Prefabricated Vertical Drain Cores
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PVD Properties
Property Amerdrain 407 Amerdrain 407F Amerdrain 607 Amerdrain 417 Mebra-Drain MD-7407 Typar 3407-1 Mebra-Drain MD-88
Core Corrugated Corrugated Corrugated Dimple Corrugated Fin
Weight (oz/yd2) 4 2.5 6 4 4 3.9
Grab Tensile Strength (lbs) 145 65 250 145 130 130
Puncture Strength (lbs) 50 50 80 50 40 40
Trapezoidal Tear (lbs) 70 70 100 70 60 56
AOS (US Sieve) 80 gt200 70 80 100 120
Core Tensile Strength (lbs) 200 200 200 200 180 180
Discharge Capacity (gpm) 1.6 1.6 1.6 1.6 1.7 1.9
All fabric and cores made from
polypropyleneAmerdrain ASTM D 4632
Mebra-Drain ASTM D 638 ASTM D4716
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Wick Drains Used in Crimp Testing
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Vertical Discharge Capacity - Hydraulic

• Vertical water flow
• Constant head 1 kPa (1.45 psi)
• Measure flowrate through wick
• Crimp with a 90 bend, measure flowrate
• Measure flowrate through empty heat shrink

Flow
Flow
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Vertical Discharge PVD Methodology

• PVDs encased in heat shrink tubing
• Uniformity critical
• Insert wick into heat shrink
• Clamp into aluminum plates, with spacers
• Heat aluminum to shrink tubing

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PVD Discharge Capacities (mL/s)
Run 1 Run 2 Run 3 Run 4 Average Flow Reduction () Standard Deviation
Amerdrain 407 240 249 244 223 27 8
Amerdrain 407F 260 220 229 240 34 7
Amerdrain 607 287 290 311 281 20 2
Amerdrain 417 310 255 247 262 27 8
Mebra-Drain MD-7407 Typar 3407-1 371 290 263 316 31 8
Mebra-Drain MD-88 447 345 404 451 17 3
Blank 692 692 457 - No flow No flow
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90 Crimp Test Results
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Horizontal Discharge Capacity

• Conforms to ASTM D4716
• Measure lateral discharge through wick
• Compact soils apply range of stresses
• Measure discharge under increasing lateral stress

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Lateral Stress Test
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Soil Types

• Four soils to be tested
• Woodrow Wilson Bridge
• Interbedded sand and clay
• West Point
• Soft clay with organics
• Craney Island
• Marine clay
• Sandy silt
• High shear strength, high permeability

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Woodrow Wilson Bridge Soil Characterization
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Craney Island Soil Characterization
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Conclusions

• Fin corrugated high strength fabric performed
  best in crimp test
• Corrugated dimple core perform similarly
• Corrugated low strength fabric had highest flow
  reduction
• Using same core, fabric strength influenced flow
  reduction, with strongest fabric showing the
  least reduction