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Foundation Fundamentals PowerPoint Presentation
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Foundation Fundamentals - PowerPoint PPT Presentation

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Foundation Fundamentals

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  1. Foundation Fundamentals GSD 6204 Building TechnologyHarvard Graduate School of Design

  2. Foundation: portion of a building that transfers structural loads to soil

  3. Types of foundations 1. Shallow foundations: slab on grade footings (continuous or point) foundation walls mat slab 2. Deep foundations: piles and caissons

  4. Shallow foundations:transfer loads to soil directly below structure

  5. Depth of shallow foundations determined by: 1. Calculation of structural loads and distribution to soil 2. Depth of winter frost in local area (particularly for residential and light construction)

  6. For maximum stability, the weight of soil excavated should be equal to the weight of the building gsd6204

  7. Pre-loading of soil gsd6204

  8. Soil compaction gsd6204

  9. Types of soils(listed from most to least stable) bedrock gravels sands silts and clays organic soils

  10. Soil fails/deforms in shearing gsd6204

  11. Uniform vs. differential soil settlement

  12. Angle of repose: f = natural slope of soil (depends on soil type) gsd6204

  13. Slope stability gsd6204

  14. Retaining wall: loads and reactions gsd6204

  15. Vertical loads on continuous footing gsd6204

  16. Crushed stone under the footing distributes load evenly gsd6204

  17. Vertical loads on a single footing gsd6204

  18. Foundation beams give rigidity to bearing; point loads are distributed evenly across an area of soil

  19. Deep foundations:transfer loads to bedrock or other highly stable soil layers well below structure, through bearing and/or friction

  20. Deep foundations: point-resisting bell caisson group gsd6204

  21. Deep foundations: floating pile group gsd6204

  22. Examples of Caisson Construction

  23. Service Crane Rebar Cage BoringUnit Dry Condition Step 2 Step 1 Boring hole using the boring unit and augur. Installing the reinforcement cage into the bored hole. Unstable Soil Clays ( including no water) Stable Soil Gravels

  24. Concrete Mixer Pipe Rebar Cage Dry Condition Step 4 Step 3 After excavation, remove the impure concrete of pile Casting concrete by direct discharge from the concrete mixer Excavation Concrete Hopper Pile cut Unstable Soil Clays ( including no water) Stable Soil Gravels

  25. Wet Condition Step 2 Step 1 Boring hole using the boring unit and augur. Installing the reinforcement cage into the bored hole. BoringUnit Rebar Cage Unstable Soil Silt or sand ( including water) Filled with stabilising fluids such as water or bentonite, (or all casing , depend on the situation) in order to prevent soil collapse Stable Soil ( Gravels )

  26. Wet Condition Step 4 Step 3 After removing slime at the bottom, discharge concrete through the pipe. The plug prevents a turbulent contact between the concrete and the water. Inserting tremie pipe down to the bottom of the borehole Filled with stabilising fluids such as water or bentonite, (or all casing , depend on the situation) in order to prevent soil collapse Service Crane Concrete Hopper Tremie Pipe Unstable Soil Tremie Pipe Silt or sand ( including water) Detail Concrete The concrete displaces the water from beneath Stable Soil ( Gravels )