Pile Foundation Design Guide

Posted by Civil Engineering on

Tuesday 7 April 2020

There are many texts on pile foundations. Generally, experience shows us that
undergraduates find most of these texts complicated and difficult to
understand.
This guide has extracted the main points and puts together the whole process of
pile foundation design in a student friendly manner.
The guide is presented in two versions: text-version (compendium from) and
this web-version that can be accessed via internet or intranet and can be used as
a supplementary self-assisting students guide.
Pile foundations are the part of a structure used to carry and transfer the load of
the structure to the bearing ground located at some depth below ground
surface. The main components of the foundation are the pile cap and the piles.
Piles are long and slender members which transfer the load to deeper soil or
rock of high bearing capacity avoiding shallow soil of low bearing capacity The
main types of materials used for piles are Wood, steel and concrete. Piles made
from these materials are driven, drilled or jacked into the ground and connected
to pile caps. Depending upon type of soil, pile material and load transmitting
characteristic piles are classified accordingly. In the following chapter we learn
about, classifications, functions and pros and cons of piles.

Function of piles

As with other types of foundations, the purpose of a pile foundations is:
to transmit a foundation load to a solid ground
to resist vertical, lateral and uplift load
A structure can be founded on piles if the soil immediately beneath its base
does not have adequate bearing capacity. If the results of site investigation
show that the shallow soil is unstable and weak or if the magnitude of the
estimated settlement is not acceptable a pile foundation may become
considered. Further, a cost estimate may indicate that a pile foundation may be
cheaper than any other compared ground improvement costs.
In the cases of heavy constructions, it is likely that the bearing capacity of the
shallow soil will not be satisfactory, and the construction should be built on
pile foundations. Piles can also be used in normal ground conditions to resist
horizontal loads. Piles are a convenient method of foundation for works over
water, such as jetties or bridge piers.

End bearing piles

These piles transfer their load on to a firm stratum located at a considerable
depth below the base of the structure and they derive most of their carrying
capacity from the penetration resistance of the soil at the toe of the pile (see
figure 1.1). The pile behaves as an ordinary column and should be designed as
such. Even in weak soil a pile will not fail by buckling and this effect need only
be considered if part of the pile is unsupported, i.e. if it is in either air or water.
Load is transmitted to the soil through friction or cohesion. But sometimes, the
soil surrounding the pile may adhere to the surface of the pile and causes
"Negative Skin Friction" on the pile. This, sometimes have considerable effect
on the capacity of the pile. Negative skin friction is caused by the drainage of
the ground water and consolidation of the soil. The founding depth of the pile is
influenced by the results of the site investigate on and soil test.

Please download attachment file to see details Pile Foundation Design Guide for student
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Labels: Foundation, RC Design, Reinforced Concrete

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