Pile

Pile FoundationBy: Muhammad Saleem Govand Jasm

Outline• Introduction• Pile foundation• Steel H-Piles• Concrete piles• Timber Piles• Classification of piles based on function • Pile cap reinforcement• Selection of Pile• Uses of pile foundations

Introduction

• Our building is rested on a weak soil formation which can’t resist the loads coming from our proposed building, so we have to choose pile foundation.

Pile foundation

• Piles are structural members that are made of steel, concrete or timber.

Steel H-Piles

Steel piles first came into use in the 1890'sTypical lengths 50 to 150 feet.Typical design loads 45 to 225 tons.

ADVANTAGES

Available in Various Lengths and Sizes. Especially useful for tension and uplift loads. Easy to Splice. High Capacity. Low Soil Displacements. May Penetrate Larger Obstructions with Driving Shoes. Remarks Best Suited for Toe Bearing on Rock.

DISADVANTAGES • Vulnerable to Corrosion.• Not Recommended as Friction Pile in Granular Soils.• Expensive compared to other piles• May be subject to corrosion, depending upon soil and water conditions

Steel H-Piles

Concrete piles

Usual length: 10m-20mUsual load: 300kN-3000kN

Advantages Corrosion resistanceCan be easily combined with a concrete superstructure

DisadvantagesDifficult to achieve proper cutoffDifficult to transport

Timber Piles

• The oldest type of pile in use.

• Most used today are Southern Pine or Douglas Fir.

• Diameters range from 6" –18”

• Lengths from 20' – 60’• Inexpensive and easy to cut

• Difficult to splice (limited length).

• Limited Bearing Capacity (< 250 KN) usually 100-200 KN (10-20 tons).

• Suitable for soft clay, loose sand and silt.

PILES

END BEARING PILE FRICTION PILE COMPACTION

PILES

CLASSIFICATION OF PILESBASED ON FUNCTION

These piles are used to transfer load through water or soft soil to a suitable bearing stratum.

END BEARING 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

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’.

COMPACTION PILE

• Pile caps carrying very heavy point loads tend to produce high tensile stresses at the pile cap.

Reinforcement is thus designed to provide:

• Resistance to tensile bending forces in the bottom of the cap • Resistance to vertical shear

Pile Cap Reinforcement

Selection of Pile

Factors governing the selection of piles

Length of the pile in relation to the load and type of soil, Characters of structure, Availability of the materials, Types of loading, Factors causing deterioration, Ease of maintenance, Estimated cost of types of piles, taking into account the initial

cost, life expectancy and cost of maintenance Availability of funds.

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

Thanks