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Pile Foundations Module #9 Prepared by Dr. Randy R. Rapp July 2005.

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Presentation on theme: "Pile Foundations Module #9 Prepared by Dr. Randy R. Rapp July 2005."— Presentation transcript:

1 Pile Foundations Module #9 Prepared by Dr. Randy R. Rapp July 2005

2 2005, Randy R. Rapp2 Site Investigation Equipment: auger (hollow-stem), split- spoon sampler, Dutch cone Data sought and recorded

3 2005, Randy R. Rapp3 Types of Bearing Friction piles –In deposits with very deep bearing strata, perhaps minimal end-bearing End-bearing piles Compaction piles

4 2005, Randy R. Rapp4 Augering Caissons

5 2005, Randy R. Rapp5 Pile Types Timber –Beware delivery and storage Cast-in-place concrete –Cased Pipe Shell Fluted –Uncased –Wet holes must be remediated

6 2005, Randy R. Rapp6 Pile Types (Contd) Precast (typically prestressed) –Plant inspection may be required –Handling is critical: beware hard-to-see failures Steel (H-pile) –Superior if splicing perhaps needed

7 2005, Randy R. Rapp7 Driving Piles Match hammer, pile, cushions for efficiency Impedance = ρ x c x A, potential capacity Specified number of blows per inch driven indicates that capacity is achieved: –Wave equation analysis by instrumentation –Empirical formulas (dynamic behavior relates to static capacity?)

8 2005, Randy R. Rapp8 Driving Piles (Contd) Count blows per foot, until design blow count approached Then count blows per inch until specification achieved Underdriving is costly, but overdriving might cause irreparable damage to any pile typevery costly Pile heave: neighboring piles, frost

9 2005, Randy R. Rapp9 Driving H-Piles for Pile Cap

10 2005, Randy R. Rapp10 Hammer Types Hammers –Drop –Air –Steam –Diesel –Vibratory Leads –Fixed: A-frame –Hanging or swinging

11 2005, Randy R. Rapp11 Pile Load Tests Load imparted to pile in gradual steps to twice design load, as settlement data recorded Often, load removed in steps, too, to produce load-deflection curve, p. 228 Behavior –Elastic deformation –Buckling –Puncture Ensure multiple deflection references, in case one is lost

12 2005, Randy R. Rapp12 Pile Load Test

13 2005, Randy R. Rapp13 Inspector Duties Review the hammer manual, if available Be sure that the contractor is consistent: –Technique –Equipment settings See pp. 241-44

14 2005, Randy R. Rapp14 Sheet Piling Differences from bearing piles –Subsurface flow cutoff –Soil retention –Alignment critical: interlock usually desired Anchored bulkheads Soil nails

15 2005, Randy R. Rapp15 Driving Sheet Piles w/ Hydraulic Hammer

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