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FOUNDATIONS 101

This article provides an overview of shallow and deep foundation systems, including shallow foundations like footings and mats, as well as deep foundations like driven piles and drilled piers. It also discusses quality control issues related to foundation construction.

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FOUNDATIONS 101

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  1. FOUNDATIONS 101 AN OVERVIEW OF SHALLOW AND DEEP FOUNDATION SYSTEMS PAUL F. MARANO, P.E.

  2. Introduction Shallow Foundations Deep Foundations Quality Control Issues INTRODUCTION • Shallow Foundations: • Footings • Mats • Deep Foundations: • Driven piles • Augered, cast-in-place piles • Helical piles • Rammed aggregate piers • Drilled piers (caissons) • Quality control issues

  3. Introduction • Shallow Foundations • Column/Wall Footings • Mat Foundations • Deep Foundations • Quality Control Issues COLUMN/WALL FOOTINGS • Appropriate for stable, near-surface soils with no underlying shallow compressible layers • Low to moderate loads (typ. 2,000-8,000 psf) • Load spread over localized soil contact area • Typically 3 feet deep for frost protection • Practical limiting depth: 7 feet

  4. Introduction • Shallow Foundations • Column/Wall Footings • Mat Foundations • Deep Foundations • Quality Control Issues COLUMN/WALL FOOTINGS

  5. Introduction • Shallow Foundations • Column/Wall Footings • Mat Foundations • Deep Foundations • Quality Control Issues COLUMN/WALL FOOTINGS • Advantages: • Economical, easy to construct • Disadvantages: • Susceptible to differential settlements • Cost: $300/c.y.

  6. Introduction • Shallow Foundations • Column/Wall Footings • Mat Foundations • Deep Foundations • Quality Control Issues MAT FOUNDATIONS • Appropriate for stable, near surface soils with no underlying compressible layers • Moderate to high column loads • Load spread over entire building footprint • Depth usually dictated by required mat thickness

  7. Introduction • Shallow Foundations • Column/Wall Footings • Mat Foundations • Deep Foundations • Quality Control Issues MAT FOUNDATIONS

  8. Introduction • Shallow Foundations • Column/Wall Footings • Mat Foundations • Deep Foundations • Quality Control Issues MAT FOUNDATIONS • Advantages: • Economical, easy to construct • Useful where property line restrictions are present • Disadvantages: • Requires continuous pour • Capacity limited by soil conditions • Longer exposure of bearing surface • Cost: $360/c.y.

  9. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DEEP FOUNDATIONSPILE CLASSIFICATION • FHWA Publication HI-97-013

  10. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DEEP FOUNDATIONS • Will Focus On: • Driven piles: • Timber piles • Steel H piles • Pipe piles • Pre-cast concrete • Augered, cast-in-place piles • Helical piles • Rammed aggregate piers • Drilled piers (caissons)

  11. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DEEP FOUNDATIONS

  12. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRIVEN PILES • Drawing courtesy of FHWA Publication HI 97-014

  13. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRIVEN PILES • Photo courtesy of University of California at Davis - Civil and Environmental Engineering Department

  14. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues TIMBER PILES • Appropriate for support when poor, near-surface soils and/or compressible layers are present • Support via end bearing and/or skin friction • For low to medium column loads • Short to medium lengths • Typical load range: 10 to 40 tons per pile

  15. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues TIMBER PILES • Drawing courtesy of NAVFAC DM-7.2

  16. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues TIMBER PILES • Advantages: • Economical • Readily available • Easy to handle • Disadvantages: • Difficult to splice • Potential head/tip damage during hard driving • Cannot penetrate very dense layers or small obstructions • Vulnerable to deterioration in wet/dry condition • Susceptible to degradation from insects • Cost: $25/ft.

  17. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues STEEL H PILES • Appropriate for support when thick layers of poor soils and/or compressible materials are present • Best suited for end-bearing support on rock • For moderate to high column loads • Short to long lengths • Typical load range: 60 to 220 tons per pile

  18. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues STEEL H PILES • Drawing courtesy of NAVFAC DM-7.2

  19. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues STEEL H PILES • Advantages: • Small displacement • Easy to splice • Available in various lengths and sizes • Can penetrate most obstructions/soft rock • Disadvantages: • Minimal skin friction • Web joint is vulnerable during hard driving • Vulnerable to corrosion • Cost: $50/ft.

  20. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PIPE PILES • Appropriate for support when moderate to thick layers of poor soils and/or compressible materials are present • Support via end bearing and skin friction • For moderate to high column loads • Medium to long lengths • Hollow or concrete filled (with or without reinforcement) • Typical load range: 70 to 200 tons per pile

  21. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PIPE PILES • Drawing courtesy of NAVFAC DM-7.2

  22. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PIPE PILES • Advantages: • Easy to splice • Internal inspection (prior to concrete placement) • Available in various lengths, diameters, and wall thicknesses • Disadvantages:a • High initial cost • Susceptible to damage during driving • Cannot penetrate very dense layers or smaller obstructions • Cost: $40/ft. (pipe only) $55/ft. (w/concrete)

  23. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PRE-CAST CONCRETE PILES • Appropriate for support when moderate layers of poor soils and/or compressible layers are present • Support via end bearing and skin friction • For moderate to high column loads or large lateral loads • Can be pre-stressed for higher capacity • Medium lengths • Typical load range: 50 to 100+ tons per pile (higher if pre-stressed)

  24. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PRE-CAST CONCRETE PILES • Drawing courtesy of NAVFAC DM-7.2

  25. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PRE-CAST CONCRETE PILES • Photo courtesy of University of California at Davis - Civil and Environmental Engineering Department

  26. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues PRE-CAST CONCRETE PILES • Photo courtesy of University of California at Davis - Civil and Environmental Engineering Department

  27. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues AUGERED, CAST-IN-PLACE PILES • Appropriate for support when moderate to thick layers of poor soils and/or compressible materials are present • No vibration, minimal installation noise • Support via end bearing and skin friction • For low to high column loads • Short to long lengths • Typical load range: 30 to 100 tons per pile

  28. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues AUGERED, CAST-IN-PLACE PILES • Drawing courtesy of L.G. Barcus and Sons

  29. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues AUGERED, CAST-IN-PLACE PILES • Photo courtesy of L.G. Barcus and Sons

  30. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues AUGERED, CAST-IN-PLACE PILES • Photo courtesy of L.G. Barcus and Sons

  31. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues AUGERED, CAST-IN-PLACE PILES • Photo courtesy of L.G. Barcus and Sons

  32. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues AUGERED, CAST-IN-PLACE PILES • Advantages: • Relatively quiet installation • No driving vibrations • No splicing required • Can be reinforced • Can be installed in low headroom locations • Disadvantages: • Highly dependent on proper installation technique • Thorough knowledge of subsurface conditions required • Possible “necking” in very soft soils • Susceptible to degradation from sulfates, chlorides, or acidic conditions • Cost: $35/ft.

  33. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues HELICAL PILES • Appropriate for support when near-surface soils and/or moderate compressible layers are present • No vibration, minimal installation noise • Support via end bearing • For low to moderate column loads • Short to medium lengths • Typical load range: 7.5 to 50 tons per pile

  34. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues HELICAL PILES

  35. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues HELICAL PILES

  36. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues HELICAL PILES • Advantages: • Relatively quiet installation • No special installation equipment • Shaft can be grouted to provide skin friction • Provides significant uplift resistance • Can be installed in low headroom locations • Can be used to supplement existing foundations • Disadvantages: • Cannot penetrate very dense layers or smaller obstructions • Minimal skin friction • Possible buckling under compression in very soft soils • Cost: $20-$30/ft. (equivalent)

  37. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues RAMMED AGGREGATE PIERS • Appropriate for support when poor near-surface soils and/or moderate compressible layers are present • Support via end bearing/densification • Install by drilling or via driven mandrel • Can increase stiffness by adding grout to the aggregate • Short to medium lengths • Typical load range: 30 to 100+ tons per pier*

  38. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues RAMMED AGGREGATE PIERS

  39. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues RAMMED AGGREGATE PIERS • Advantages: • Densifies/stiffens surrounding poor soils • Materials (aggregate) readily available • Can increase stiffness by adding grout • Disadvantages: • Highly dependent on proper installation • Difficulty penetrating dense materials or small obstacles • Proprietary technique • Need aggregate mat at surface • Cost: $30-$60/ft.*

  40. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS) • Appropriate for support when near-surface soils and/or compressible layers are present • Low vibration, low noise installation • Support via end bearing • For high column loads • Short to medium lengths • Typical load range: 150 to 2,000+ tons per pier

  41. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS)

  42. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS)

  43. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS) • Photo courtesy of University of California at Davis - Civil and Environmental Engineering Department

  44. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS) • Photo courtesy of University of California at Davis - Civil and Environmental Engineering Department

  45. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS)

  46. Introduction • Shallow Foundations • Deep Foundations • Timber Piles • Steel H Piles • Pipe Piles • Pre-Cast Concrete Piles • Augered, Cast-In-Place Piles • Helical Piles • Rammed Aggregate Piers • Drilled Piers • Quality Control Issues DRILLED PIERS (CAISSONS) • Advantages: • Can increase capacity by belling or with socket in competent material or rock • Bearing surface can be evaluated* • No vibration • Can be readily modified based on field conditions • No pile cap needed • Disadvantages: • Highly dependent on proper installation technique and clean out • Large amounts of drilling spoils • Obstructions (boulder) removal difficult • Cost: $60/c.y.

  47. Introduction Shallow Foundations Deep Foundations Quality Control Issues Load Testing Driven Piles Drilled Piers QUALITY CONTROL ISSUES • Why Perform a Load Test? • Local regulations • Design loads are significantly higher than local practice • Potential for substantial cost savings • Existing piles are reused for heavier design loads • Safe design loads are in doubt • Static load test (ASTM D 1143) • Dynamic load test (ASTM D 4945)

  48. Introduction Shallow Foundations Deep Foundations Quality Control Issues Load Testing Driven Piles Drilled Piers QUALITY CONTROL ISSUES

  49. Introduction Shallow Foundations Deep Foundations Quality Control Issues Load Testing Driven Piles Drilled Piers QUALITY CONTROL ISSUES

  50. Introduction Shallow Foundations Deep Foundations Quality Control Issues Load Testing Driven Piles Drilled Piers QUALITY CONTROL ISSUES • Driven Pile Specifications: • Site/Project Conditions - include geotechnical report (for information purposes) • Fabrication (Pile Markings) - every 6 inches, with distances marked every foot • Concrete Mixes - is air entrainment necessary? • Driving Equipment - hammer should be approved by geotechnical design engineer

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