Foundation Engineering CE 483

Name: Foundation Engineering CE 483
Uploaded: 2017-06-27T23:37:18+00:00
Duration: PTM22S19
Channel: Mabel White
Description: Foundation Engineering CE 483

Foundation Engineering CE 483
3. Types of foundation & foundation materials Copy right reserved to Dr O. Hamza

CE 483 - Foundation Engineering - 3. Types of Foundations
Contents Introduction Shallow Foundations Deep Foundations Copy right reserved to Dr O. Hamza CE Foundation Engineering Types of Foundations

Introduction Why different types of foundations? General types of foundations Three Ws  three dimensions to find a space CE Foundation Engineering Types of Foundations

Introduction Why different types of foundations? What type of foundation you choose will depend upon many factors: Structure: type, use, loadings, code requirement. Ground: layers, subsurface soil condition, groundwater. Cost CE Foundation Engineering Types of Foundations

Low-rise building supported by
Introduction General types of foundations Foundation might be: Shallow, or Deep They could be constructed from: Concert (reinforced) Steel Other materials: Timber, Stones,… High building Low-rise building supported by Shallow foundations (footings) Deep foundation (piles)

Shallow foundations Definition Advantages Types of shallow foundations Three Ws  three dimensions to find a space CE Foundation Engineering Types of Foundations

Shallow foundations Definition Shallow foundations are those founded near to the finished ground surface; generally where the founding depth (Df) is less than the width of the footing (B) and generally less than 3m. Shallows foundations are used when surface soils are sufficiently strong and stiff to support the imposed loads. They are generally unsuitable in weak or highly compressible soils, such as poorly-compacted fill, peat, and alluvial deposits, etc. Df B CE Foundation Engineering Types of Foundations

Shallow foundations Advantages Cost (affordable) Construction procedures (simple) Material (mostly reinforced concrete) Labor (doesn’t need high experience) CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) often rectangular or square and are used to support single columns. This is one of the most economical types of footings and is used when columns are spaced at relatively long distances. 1 Pad foundations Strip foundation Column 2 Pad footing 3 Column Column CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) 1 Pad foundations Strip foundation Strip footings are continuous foundation used to support walls. 2 Wall 3 Strip, continuous, or wall footing CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) Combined footings are used when two columns are so close that single footings cannot be used or when one column is located at or near a property. 1 Column Column Cross section 2 Rectangular Trapezoidal combined footing Strap footing Footing 3 Plan view CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) 1 Column Column 2 Rectangular Trapezoidal View plan of Trapezoidal combined Footing 3 CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) Consist of two single footings connected with a beam or a strap and support two single columns. This type replaces other combined footings and is more economical. 1 Column Column Cross section Strap 2 Footing Footing Rectangular Trapezoidal Strap Strap beam 3 Plan view CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) 1 Consists of one slab usually placed under the entire building area. Column Cross section 2 Footing Plan view 3 CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Raft foundations are used, when soil bearing capacity is low, column loads are heavy, single footings cannot be used, piles are not used, and differential settlement must be reduced. Shallow Foundation Spread Combined Mat (Raft) 1 2 3 Steel reinforcement for the raft CE Foundation Engineering Types of Foundations

Shallow foundations Types of shallow foundations Shallow Foundation Spread Combined Mat (Raft) 1 A raft foundation normally consists of a concrete slab which extends over the entire loaded area. It may be stiffened by ribs or beams incorporated into the foundation. 2 Raft Beam 3 Soft soil CE Foundation Engineering Types of Foundations

Deep foundations Definition Types of deep foundations CE Foundation Engineering Types of Foundations

Deep foundations Definition Deep foundations are those founding too deeply below the finished ground surface for their base bearing capacity to be affected by surface conditions, this is usually at depths >3 m below finished ground level. Deep foundations are used when there are weak soils near the surface or when loads are very high, such as very large skyscrapers. Deep foundations derive their support from deeper soils or bedrock. High building Soft soil Bedrock CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 2 3 4 CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations Piles are relatively long, slender members that transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having a high bearing capacity. 1 2 Piles used as a foundation for structure 3 4 CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations In addition to supporting structures, piles are also used to anchor structures against uplift forces and also to assist structures in resisting lateral and overturning forces. 1 2 3 4 Piles used as a retaining wall CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations Pile caps are thick slabs used to tie a group of piles together to support and transmit column loads to the piles. 1 2 Column Pile Cap Cross section Piles 3 4 Plan CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations Pile length and size have to be designed to tolerate all possible loading conditions. 1 2 Column 3 4 Broken Piles CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations Pile length and size should be designed to tolerate all possible loading conditions. 1 2 Column 3 Shanghai building collapse 4 Broken Piles CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 Based on method of installation: Driven piles (displacement piles): made of steel, pre-stressed concrete, timber, or composite. Bored piles (replacement piles): Augured and cast in-situ. Other piles: Sheet-pile, Micropiles, Suction Piles, Vibrated Stone Columns 2 3 4 CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Driven Piles Deep Foundation Piles Piers Caissons Compensated foundations 1 Board piles Driven piles 2 3 4 CE Foundation Engineering Types of Foundations

Types of deep foundations
Piles Piers Caissons Compensated foundations 1 Driven or displacement piles 2 3 4

Deep foundations Types of deep foundations Bored piles Deep Foundation Piles Piers Caissons Compensated foundations Pile length and size have to be designed to tolerate all possible loading conditions. 1 2 3 4 CE Foundation Engineering Types of Foundations

Piles Piers Caissons Compensated foundations 1 Bored or replacement piles length can be varied, very long lengths possible removed soil can be compared with design data penetration tests can be carried out in boreholes very large bases can be possibly formed drilling tools can break up boulders, obstructions,.. little noise and vibration during construction no ground heave Advantages: 2 3 Disadvantages: piles liable to squeezing and necking in soft soil special techniques required for concreting in water bearing ground concrete cannot be inspected after installation enlarged bases cannot be formed in collapseable soil cannot be easily extended above ground boring may cause instability and settlement of adjacent structures 4

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 Piers are foundations for carrying a heavy structural load which is constructed in-situ in a deep excavation. 2 3 4 CE Foundation Engineering Types of Foundations

Deep foundations Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 2 3 Caissons are a form of deep foundation which are constructed underwater above seabed, then sunk to the required level by excavating or dredging material from within the caisson. 4 CE Foundation Engineering Types of Foundations

Piles Piers Caissons Compensated foundations These are deep foundations in which the relief of stress due to excavation is approximately balanced by the applied stress due to the foundation. 1 The net stress applied is therefore very small. A compensated foundation normally comprises a deep basement. 2 Original Site Remove soil equal in weight to the building 3 Soft soil susceptible to settlement or low bearing strength Soil pressure at this level is no greater than when original soil was in place 4 CE Foundation Engineering Types of Foundations

References Braja M Das, 2011, Principles of Foundation Engineering,, 7th ed. Previous course materials at KSU s/Pile%20Foundations%20v1.00%20Oct2010.pdf Geotechnical on the web: CE Foundation Engineering Types of Foundations

Foundation Engineering CE 483

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