PILE TESTING

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PILE TESTING

• Mike Turner
• (Applied Geotechnical Engineering)

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Types of load testing

• Static load testing
• Maintained Load (ML)
• Constant Rate of Penetration (CRP)
• Dynamic load testing

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Static load tests on micropiles

• Features
• High slenderness ratio (Aspect Ratio)
• Relatively high elastic shortening
• Implies
• Long piles large pile head settlement

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Pile length vs Pile head settlement at working
load Micropiles in soils
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Pile length vs settlement at working
loadMicropiles in soils (2)
0.5mm/m
0.25mm/m
0.1mm/m
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Pile length vs Gross pile head settlement at
working load Micropiles into rock
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Pile length vs settlement at working
loadMicropiles into rock (2)
0.4mm/m
0.35mm/m
0.2mm/m
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Summary (1)

• For a wide variety of soils
• Gross pile settlement at working load is
• Proportional to pile length
• Around 0.25mm/metre, on average
• (As high as 0.5mm/metre)
• (As low as 0.1mm/metre)
• Independent of diameter (and load)

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Summary (2)

• For a wide variety of rocks
• Gross pile settlement at working load is
• Proportional to pile length
• Around 0.35 mm/metre, on average
• (As high as 0.4 mm/metre)
• (As low as 0.2 mm/metre)
• Independent of diameter (and load)

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Spooky!
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Pile head settlement vs working load Micropiles
in soils
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Pile head settlement vs working load Micropiles
in soils (2)
0.012mm/kN
0.005mm/kN
0.035mm/kN
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Pile head settlement vs working load Micropiles
into rock
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Pile head settlement vs working load Micropiles
into rock (2)
0.01mm/kN
0.004mm/kN
0.02mm/kN (variable)
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Summary (1)

• For a wide variety of soils
• Gross pile head settlement at working load is
• Around 0.012 mm/kN (0.1mm/tonne metric)
• As high as 0.035mm/kN (0.35 mm/tonne)
• As low as 0.005 mm/kN (0.05 mm/tonne)
• (Fairly) independent of length and actual load!

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Summary (2)

• For a wide variety of rocks
• Gross pile head settlement at working load is
• Around 0.01 mm/kN (0.1mm/tonne metric)
• (for most practical
  purposes)
• May be as high as 0.02 mm/kN (0.2 mm/tonne)
• May be as low as 0.004mm/kN (0.04 mm/tonne)
• Still fairly independent of length and load!

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Even spookier!
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Conclusion/discussion

• Apparent similarities of relationships?
• Bearing stratum generally stronger than
• 
  overburden
• Piles designed on shaft friction alone
• Grout-to-ground design conservative
• Structural design essentially identical