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

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

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

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

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

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

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

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)

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)

Spooky!

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

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

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

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

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!

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!

Even spookier! August 2004 Pile Testing

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