1. Mike Turner (Applied Geotechnical Engineering)
PILE TESTING
Mike Turner
(Applied Geotechnical Engineering)

2. Types of load testing Static load testing Maintained Load (ML)
Constant Rate of Penetration (CRP)
Dynamic load testing
August 2004
Pile Testing

3. Static load tests on micropiles
Features:
High slenderness ratio (=Aspect Ratio)
Relatively high elastic shortening
Implies:
Long piles = large pile head settlement
August 2004
Pile Testing

4. Pile length vs Pile head settlement at working load: Micropiles in soils
August 2004
Pile Testing

5. Pile length vs settlement at working load Micropiles in soils (2)
0.5mm/m
0.25mm/m
0.1mm/m
August 2004
Pile Testing

6. Pile length vs Gross pile head settlement at working load – Micropiles into rock
August 2004
Pile Testing

7. Pile length vs settlement at working load Micropiles into rock (2)
0.4mm/m
0.35mm/m
0.2mm/m
August 2004
Pile Testing

8. 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)

9. 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)

10. Spooky!

11. Pile head settlement vs working load: Micropiles in soils
August 2004
Pile Testing

12. Pile head settlement vs working load: Micropiles in soils (2)
0.005mm/kN
0.012mm/kN
0.035mm/kN
August 2004
Pile Testing

13. Pile head settlement vs working load: Micropiles into rock
August 2004
Pile Testing

14. Pile head settlement vs working load: Micropiles into rock (2)
0.004mm/kN
0.01mm/kN
0.02mm/kN (variable)
August 2004
Pile Testing

15. Summary (1) For a wide variety of soils:
Gross pile head settlement at working load is:
Around mm/kN (0.1mm/tonne [metric])
[As high as 0.035mm/kN (0.35 mm/tonne)]
[As low as mm/kN (0.05 mm/tonne)]
(Fairly) independent of length and actual load!

16. 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!

17. Even spookier!
August 2004
Pile Testing

18. 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