Deep Foundation Deign Methods Pile Selection Guide 1 Ultimate Pile Load Capacity Shaft Resistance 2 Shaft Capacity in Clay (Alpha Method) Shaft Capacity in Clay (Alpha Method) 3 Shaft Capacity in Clay (Alpha Method) Soft-stiff clay Adhesion factors 4 © Learning™ / Thomson Publishing 2004 Brooks/Cole Nature of variation of undrained shear strength (cu) with time around a pile driven into soft clay © Learning™ / Thomson Publishing 2004 Brooks/Cole Variation of Qs with time for a pile driven into soft clay (based on load test results of Terzaghi and Peck, 1967) 5 © Learning™ / Thomson Publishing 2004 Brooks/Cole Compaction of sand near driven piles (after Meyerhof, 1961) = pile critical depth © 2004 Brooks/Cole Publishing / Thomson Learning™ Unit frictional resistance for piles in sand 6 • For z = 0 to L’ fs = Kσo’tanδ=βtanδ Where β = Kσo’ • For z = L’ to L fs = fz=L Qs = fs Σp ΔL Where p = perimeter of pile ΔL = incremental pile length which p and fs are taken constant Shaft Capacity in Sand (Beta Method) δ is the shaft soil friction angle 7 Shaft Capacity in Sand (Beta Method) Shaft Capacity in Sand (Beta Method) 8 Vesic Tests Shaft Capacity in Sand (Practical Design) 9 Shaft Resistance End Bearing 10 End Bearing Failure Assumptions End Bearing Failure Assumptions 11 End Bearing Factor (Nq) End Bearing based on SPT 12 End Bearing Layered Soils End Bearing Issues 13 Cone Penetration Test (cpt) Shaft Resistance in Clays 14 Shaft Resistance in SAND Beware of variability with different methods End Bearing 15 Piles to Rock Piles to Rock 16 Importance of Shaft Friction Piles to Rock a, b reduction factors (Williams & Pells 1981) 17 Piles to Rock End Bearing Parameters Uplift Capacity 18 Uplift Capacity SAND Uplift Capacity SAND Single Pile 19 Cyclic Loading Cyclic Stability Diagram 20 Negative Skin Friction Down drag due to settlement © 2004 Brooks/Cole Publishing / Thomson Learning™ 21 © Learning™ / Thomson Publishing 2004 Brooks/Cole Negative skin friction on a pile in the harbor of Oslo, Norway (based on Bjerrum et al. (1969) and Wong and Teh (1995) Pile Groups © Learning™ / Thomson Publishing 2004 Brooks/Cole 22 Pile Group Efficiency © Learning™ / Thomson Publishing 2004 Brooks/Cole 23 © Learning™ / Thomson Publishing 2004 Brooks/Cole Friction Pile Groups in Clay 24 Block Analysis © Learning™ / Thomson Publishing 2004 Brooks/Cole © 2004 Brooks/Cole Publishing / Thomson Learning™ 25 © 2004 Brooks/Cole Publishing / Thomson Learning™ © Learning™ / Thomson Publishing 2004 Brooks/Cole 26 Other Pile Group Cases Effect of Weak Under Layer 27 Pile Structural Design Buckling 28 Buckling Corrosion Rates for Steel 29 Corrosion Protection Methods 30.