Foundation

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Different Types Of Foundation

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  • It defined as the depth of foundation is less than or equal to Breadth of foundation. Shallow foundations are generally for 2 to 3m depth
  • Foundation

    1. 1. PREPARED BY Mohit Goyal Civil Engineer FOUNDATIONS
    2. 2. OBJECTIVES To know the construction of foundation To know the different types foundations To know which type of foundation is suitable for different types soils.
    3. 3. FOUNDATION  Every structure consists of two parts:  Sub-structure or foundation and  Super structure Foundation : It is the lowest part of a structure which is constructed below the ground level.  The function of foundation is to transmit the weight of super structure to the sub soil.
    4. 4. TYPES OF FOUNDATIONS 1. SHALLOW FOUNDATIONS (D<= B) 2. DEEP FOUNDATIONS (D>= B) D B G L FOUNDATION TRENCH
    5. 5. TYPES OF FONDATIONS 1. SHALLOW FOUNDATIONS  WALL FOUNDATION  ISOLATED COLUMN FOUNDATION  COMBINED FOUNDATION  MAT OR RAFT FOUNDATION 2. DEEP FONDATIONS  PILE FOUNDATIONS  UNDER-REAMED PILE  WELL FOUNDATIONS
    6. 6. WALL FOUNDATION RAMMER FOUNDATION TRENCH SAND OR PEIECES OF BRICKS ETC..,
    7. 7. P C C WALL SIMPLE FOUNDATION P C C I FOOTING WALL STEPPED FOUNDATION II FOOTING WALL FOUNDATION
    8. 8. ISOLATED FOOTING It is provided under columns to transfer the load safely to bed soil These footings may be slab, stepped or sloped ones. P C C FOOTING COLUMN
    9. 9. COMBINED FOOTING A combined footing is the one which supports two columns and it may be rectangular or trapezoidal in plan. The aim is to get uniform pressure distribution under the footing. For this the center of gravity of the footing area should coincide with the center of gravity of the combined loads of the two columns. Combined footings are used in the following situations: When the columns are very near to each other so that their footings overlap. When the bearing capacity of the soil is less, requiring more area under individual footing. When the end column is near a property line so that its footing cannot spread in that direction.
    10. 10. R C C SLABc c COMBINED FOOTING
    11. 11. MAT FOUNDATION It is most suitable foundation when the soil at the site proposed for the construction of a structure is erratic, soft clay, made up ground or marshy land with low bearing capacity. Mat foundation is constructed of RCC slab covering the whole area of the bottom of the structure. The slab is provided with steel reinforcing bars in both directions. When column loads are heavy, the main beams and secondary beams are provided monolithically with raft slab.
    12. 12. PCC BED R C C SLAB C C SECTION ALONG AA MAT FOUNDATION COLUMN A A MAIN BEAM SECONDARY BEAM MAIN BEAM
    13. 13. PILE FOUNDATIONS Pile foundation is more commonly used in building construction. Pile foundations are used in the following situations: The load of the super structure is heavy and its distribution is uneven The top soil has poor bearing capacity The subsoil water level is high There is large fluctuations in subsoil water level Canal or deep drainage lines exist near the foundation The structure is situated on the sea shore or river bed
    14. 14. PILES END BEARING PILES FRICTION PILES ANCHOR PILESTENSION PILESCOMPACTION PILES CLASSIFICATION OF PILES BASED ON FUNCTION PILES CONCRETE PILES TIMBER PILES STEEL PILES COMPOSITE PILES PRE-CAST PILES CAST-IN SITU PILES H - PILE PIPE PILE SHEET PILE CONCRETE AND TIMBER CONCRETE AND STEEL
    15. 15. END BEARING PILE : These piles are used to transfer load through water or soft soil to a suitable bearing stratum. END BEARING PILE SOFTSOIL
    16. 16. FRICTION PILE: These piles are used to transfer loads to a depth of a friction load carrying material by means of skin friction along the length of pile. FRICTION PILE
    17. 17. COMPACTION PILECOMPACTION PILE COMPACTION PILE: these piles are used to compact loose soils, thus increasing their bearing capacity. The compaction piles themselves do not carry any load.Hence they may be of weaker material (sand). The pile tube, driven to compact the soil, is gradually taken out and sand is filled in its place thus forming a ‘sand pile’.
    18. 18. UNDER REAMED PILE In black cotton soils and other expansive type of soils, buildings often crack due to relative ground movements. This is caused by alternate swelling and shrinking of the soil due to changes in its moisture content. The under-reamed pile is used to safe guard this movement effectively. Generally this foundation is used for machine foundation, factory building, transmission line towers and other tall structures also.
    19. 19. BORE HOLE UNDER-REAMED EQUIPMENT
    20. 20. UNDER-REAMED PILEUNDER-REAMED PILE
    21. 21. WELL FOUNDATION  Well foundation is a box of timber, metal, reinforced concrete or masonry which open both at the top and bottom, and is used for building for building and bridge foundations. Types of well shapes:  Circular  Rectangular  Double – D  Twin circular etc..,
    22. 22. CUTTING EDGE CURB STEINING BOTTOM PLUG TOP PLUG WELL CAP PIER WELL FOUNDATIONWELL FOUNDATION SAND FIILING
    23. 23. FRAMED STRUCTURE
    24. 24. Factors affecting choice of foundation The type of construction. The magnitude of load. Drainage conditions. Feasibility in terms of available skilled labors and cost. The type and bearing capacity of soil. The seismic hazard and vulnerability of site to earthquake.
    25. 25. Construction of foundation Construction of foundation consists upon the following activities: Site preparation Site layout Excavation Pour footing Pour slab on grade Pour concrete foundation walls
    26. 26. Site Preparation • Remove trees and any debris • Remove top soil (4-6” below surface)
    27. 27. Site Layout • Define the boundaries by using chalk powder. • Layout building perimeter, Establish building corners & building perimeter. •Use surveying instruments
    28. 28. Excavation •Excavate foundation along line created. •Excavate remainder of soil inside perimeter •(Don’t excavate inside soil if slab on grade) •If deep foundation, taper edges to prevent collapse •If soil unstable, or very deep - use shoring
    29. 29. Pour Footings •Construct formwork (if required) •Install reinforcement (rebar) for footing. •Pour concrete footings •Smooth / finish surface
    30. 30. Pour Slab on Grade •Install gravel base (to keep water off of slab) •Install moisture barrier (to keep water off of slab) •Install reinforcement (welded wire fabric) •Pour concrete slab •Finish slab surface
    31. 31. Pour Concrete Foundation Walls •Construct formwork (include sleeves / doors / windows) •Install reinforcement into formwork •Pour concrete foundation wall •Install anchor bolts into semi-cured concrete
    32. 32. Pour Concrete Foundation Walls •Allow concrete to cure adequately (7-10 days) •Strip forms •Apply waterproofing •Backfill
    33. 33. Protecting Foundation Against Moisture
    34. 34. Waterproofing  Structures Below Ground subject to penetration of ground water  More extreme, if below H2O table  Two basic approaches to Waterproofing – Waterproof Membranes, or – Drainage – Generally - both used in tandem
    35. 35. Waterproofing Membranes  Materials – Liquid or sheet (plastic, asphaltic, synthetic rubber) – Coatings (asphaltic) – Cementitious plasters & admixtures – Bentonite clay  Protecting boards or panels – Protection board – Water stop » Unit of measure - SF, in (thickness)
    36. 36. Stone & Perforated Pipe Drainage Mat & Perforated Pipe Drainage Methods
    37. 37. Damp proofing Typically, a liquid asphalt Applied with a Roller or sprayer Not an effective barrier For water under pressure. But, will prevent ground ‘Moisture’ from migrating Through a wall. Typically used in conjunction Will drainage pipe.
    38. 38. Underpinning Underpinning is the process of strengthening the foundation of an existing building or other structure. Underpinning may be necessary for A variety of reasons: The original foundation is simply not strong or stable enough. The usage of the structure has changed. The properties of the soil supporting the foundation may have changed (possibly through subsidence) or were mischaracterized during design. The construction of nearby structures necessitates the excavation of soil supporting existing foundations.
    39. 39. •To increase the depth or load capacity of existing foundations to support the addition of another storey to the building (above or below grade). •It is more economical, due to land price or otherwise, to work on the present structure's foundation than to build a new one. •Earthquake, flood, drought or other natural causes have caused the structure to move, thereby requiring stabilization of foundation soils and/or footings. •Underpinning may be accomplished by extending the foundation in depth or in breadth so it either rests on a more supportive soil stratum or distributes its load across a greater area. Use of micro pilesand jet grouting are common methods in underpinning

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