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

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Contents Introduction Shallow Foundations Deep Foundations CE 483 - Foundation Engineering - 3. Types of Foundations 2 Copy right reserved to Dr O. Hamza

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Introduction CE 483 - Foundation Engineering - 3. Types of Foundations 3 Why different types of foundations? General types of foundations

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Why different types of foundations? CE 483 - Foundation Engineering - 3. Types of Foundations 4 What type of foundation you choose will depend upon many factors: Structure: type, use, loadings, code requirement. Ground: layers, subsurface soil condition, groundwater. Cost Introduction

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

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Shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations 6 Definition Advantages Types of shallow foundations

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Shallow foundations 7 Definition CE 483 - Foundation Engineering - 3. Types of Foundations Shallow foundations are those founded near to the finished ground surface; generally where the founding depth (D f ) 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. DfDf B

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Shallow foundations 8 Advantages CE 483 - Foundation Engineering - 3. Types of Foundations Cost (affordable) Construction procedures (simple) Material (mostly reinforced concrete) Labor (doesnt need high experience)

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Shallow foundations 9 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3

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Shallow foundations 10 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 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. Column Pad footing Pad foundations Strip foundation

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Shallow foundations 11 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 Pad foundations Strip foundation Strip footings are continuous foundation used to support walls. Strip, continuous, or wall footing Wall

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Shallow foundations 12 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 Rectangular Trapezoidal combined footing Strap footing Column Footing Plan view Cross section 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.

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Shallow foundations 13 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 Rectangular Trapezoidal Column View plan of Trapezoidal combined Footing

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Shallow foundations 14 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 Rectangular Trapezoidal Strap 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. Column Footing Plan view Cross section Column Footing Strap Strap beam

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Shallow foundations 15 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 Consists of one slab usually placed under the entire building area. Column Footing Plan view Cross section

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Shallow foundations 16 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 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. Steel reinforcement for the raft

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Shallow foundations 17 Types of shallow foundations CE 483 - Foundation Engineering - 3. Types of Foundations Shallow Foundation Spread Combined Mat (Raft) 1 2 3 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. Soft soil Raft Beam

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Deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations 18 Definition Types of deep foundations

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Deep foundations 19 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. Definition High building CE 483 - Foundation Engineering - 3. Types of Foundations Bedrock Soft soil

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Deep foundations 20 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2

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Deep foundations 21 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 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. Piles used as a foundation for structure

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Deep foundations 22 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 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. Piles used as a retaining wall

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Deep foundations 23 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Pile caps are thick slabs used to tie a group of piles together to support and transmit column loads to the piles. Piles Plan Pile Cap Cross section Column

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Deep foundations 24 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Pile length and size have to be designed to tolerate all possible loading conditions. Column Broken Piles

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Deep foundations 25 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Pile length and size should be designed to tolerate all possible loading conditions. Column Broken Piles Shanghai building collapse

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Deep foundations 26 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 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

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Deep foundations 27 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Board piles Driven piles Driven Piles

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Deep foundations 28 Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Driven or displacement piles

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Deep foundations 29 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Pile length and size have to be designed to tolerate all possible loading conditions. Bored piles

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Deep foundations 30 Types of deep foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 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: -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 Disadvantages:

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Deep foundations 31 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 Piers are foundations for carrying a heavy structural load which is constructed in-situ in a deep excavation.

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Deep foundations 32 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 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.

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Deep foundations 33 Types of deep foundations CE 483 - Foundation Engineering - 3. Types of Foundations Deep Foundation Piles Piers Caissons Compensated foundations 1 3 4 2 These are deep foundations in which the relief of stress due to excavation is approximately balanced by the applied stress due to the foundation. Original Site Soft soil susceptible to settlement or low bearing strength Remove soil equal in weight to the building Soil pressure at this level is no greater than when original soil was in place The net stress applied is therefore very small. A compensated foundation normally comprises a deep basement.

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Reference s 34 Braja M Das, 2011, Principles of Foundation Engineering,, 7th ed. Previous course materials at KSU http://www.slideshare.net/stootypal/types-of-foundation http://data.bolton.ac.uk/staff/phm2/files/Semester1/J3%20PJ4%20Geotechnic s/Pile%20Foundations%20v1.00%20Oct2010.pdf http://data.bolton.ac.uk/staff/phm2/files/Semester1/J3%20PJ4%20Geotechnic s/Pile%20Foundations%20v1.00%20Oct2010.pdf Geotechnical on the web: http://environment.uwe.ac.uk/geocal/foundations/founbear.htm. http://environment.uwe.ac.uk/geocal/foundations/founbear.htm CE 483 - Foundation Engineering - 3. Types of Foundations