BASIC CIVIL FONDATION BY CIVIL1ST SEM (1).ppt

BASIC CIVIL FONDATION BY CIVIL1ST SEM (1).ppt

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  Basic Civil Engineering-Foundatio n CIVIL3-1 SEMESTER BUILDING MATERIALS & CONSTRA CTION BHEEMA INSTITUTE OF TECHNOLOGY AND SCIENCE ADON I
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  Foundation
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  Foundation • Introduction : •A structure essentially consists of two parts, namely the super structu re which is above the plinth level and the substructure which is below the plinth level. • Substructure is otherwise known as the foundation and this forms the base for any structure. Generally about 30% of the total construction cost is spent on the foundation. • The soil on which the foundation rests is called the “foundation soil”. • Objectives of a foundation : A foundation is provided for the following purposes: • To distribute the total load coming on the structure on a larger are a. • To support the structures. • To give enough stability to the structures against various disturbin g forces, such as wind and rain. • To prepare a level surface for concreting and masonry work.
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  Foundation… • Types offoundation : The two main types of foundation ar e : • Shallow foundation (spread foun dation) and • Deep foundation Types of Shallow foundation : • Isolated footing (single footing, C olumn footing) • Combined footing Types of Deep foundation : • Pile foundation • Pier foundation Types of Pile foundation : • Friction pile • Load bearing pile Note : Under-reamed piles is a type of load bearing pile
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  Foundation… • Shallow foundation(spread fou ndation): • Depth of foundation is less than or equal to its width. • Isolated footing (single footing, column footing): • In framed structures where sev eral columns are to be construc ted, isolated footings can be ad opted. • The columns involved can be p rovided with masonry or concre te footing. • If masonry footing is provided, steps are given and the foundat ion area is thus increased so th at the stresses developed at th e base is within the limit. • In case of masonry footing, the pr ojection of each step must be ½ br ick thick and each step is made of 1 or 2 bricks put together. • Concrete can be moulded to any s hape and hence a concrete footin g may be a sloping one to provide sufficient spread.
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  Foundation… • Isolated footing(single footing, column footing)…
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  Foundation… • Isolated footing(single footing, column footing)…
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  Foundation… • Isolated footing(single footing, column footing)… wall footing
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  Foundation… • Combined footing: •This type of footing is adopte d when the space between tw o columns is so small that the foundation for individual colu mns will overlap. • Combined footings are propo rtioned in such a way that the centre of gravity of the loads coincides with the centre of g ravity of the foundation. Henc e these footings have either a trapezoidal or a rectangular s hape. Footing : Footings are structural members u sed to support columns and walls and to transmit and distribute their loads to the soil in such a way that the load bearing capacity of the so il is not exceeded. Also excessive settlement, differential settlement or rotation are prevented and adeq uate safety against overturning or sliding is maintained.
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  Foundation… • Pile : •A slender, structural member consisting steel or concrete or timber. • It is installed in the ground to tr ansfer the structural loads to so ils at some significant depth bel ow the base of the structure.
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  Foundation… Pile caps arethick slabs used t o tie a group of piles together to support and transmit column lo ads to the piles.
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  Foundation… • Deep foundation: • Deep foundation consists of pil e and pier foundations. • This consists in carrying down t hrough the soil a huge masonry cylinder which may be supporte d by the sides of soil or may be supported on solid rock (hard st ratum). • Pile foundation : • Pile is an element of constructi on used as foundation. It may b e driven in the ground vertically or with some inclination to trans fer the load safely.
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  Foundation… • Pile foundation… •Loads are supported in two wa ys. • If the load is supported by the e ffect of friction between the soil and the pile skin, it is called frict ion pile. • Friction piles may be made of c ast iron, cement concrete, timb er, steel, wrought iron and com posite materials. • If the load is supported by resti ng the pile on a very hard stratu m, it is called load bearing pile. • Load bearing piles are steel sh eet piles, concrete piles and tim ber piles. • Piles may be cast-in-situ or precast. • They may be cased or unca sed.
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  Load Beari ng Pile FrictionPiles
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  Load bearing pil e FrictionPile
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  TYPES OF PILES •Concrete Piles i) Cast-In-Situ Concrete Piles a) Cased cast-in-situ b) Uncased cast-in-situ ii) Precast Concrete Piles • Steel Piles i) H-Piles ii) Cylindrical piles iii) Tapered piles • Timber Piles • Composite Piles
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  TYPES OF PILECONSTRUCTION 1. Displacement Piles It cause the soil to be displaced radially as well as vertically as pile shaf t is driven or jacked into the ground. b) Non Displacement Piles (Replacement piles) It cause the soil to be removed and the resulting hole filled with concret e or a pre cast concrete pile is dropped into the hole and grouted in. Displacement Pile Non Displacement pile
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  METHOD OF INSTALLATION •Dropping Weight or Drop Hammers - commonly used method of insertion of displacement piles • Diesel Hammers -Most suitable to drive pile in non cohesive granular soil • Vibratory Hammers or vibratory method of pile driving -very effective in driving piles through non cohesive granular soil • Jacking Method Of Insertion NOORBASHAWAQAS
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  Pile installation usingDrop Hammer
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  Pile Driving Rig- temporarily support the pile that bein g driven and to support the pile hammer.
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  Jacking Method OfInsertion • Jacked Piles are most commonly used in underpinning structures • By excavating underneath a structure short lengths of pile can be insert ed and jacked into the ground using the underside of the existing struct ure as a reaction.