Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 9 FOUNDATION ENGINEERING
9 DEEP FOUNDATION ENGINEERING
9.1
INTRODUCTION
In general, deep foundation using piles are relied upon to transfer the load
acting on the
superstructures in situations where the use of shallow foundations becomes inadequate or unreliable.
Some of the situationss where piles are required are as follows:
• To
transfer loads through water or soft soil to a suitable bearing stratum by means of end
bearing of the piles (end bearing or point bearing piles).
• To
transfer loads to a depth of a relatively
weak soil by
means of "skin friction" along the length
of the piles (friction piles).
• To
compact granular soils, thus increasing
their bearing capacity (compaction piles).
• To
carry the foundation through the depth of scour to provide safety in the event the soil is
eroded away.
• To
anchor down
the structures subjected to uplift due to hydrostatic (Pressure or overturning
moment (tension pile or uplift pile).
• To
provide anchorage against horizontal pull from sheetpiling walls or other pulling forces
(anchor piles).
• To
protect water front structures against impact from ships or other floating objects (fender piles
and dolphins).
• To
resist large horizontal or inclined forces (batter piles).
Foundation can be divided into two main categories, namely shallow foundation and deep foundation.
The common type of foundation is shown in Figure 9.1 below.
Foundations
Shallow
Foundations
Deep
Foundations
Spread
Footings
Mat
Foundations
Driven
Piles
Drilled
Shafts
Auger Cast
Piles
Figure 9.1 Types of Foundation
This Chapter discusses the principles and design of deep foundation. For shallow foundation, reader
can refer to Chapter 4 and Chapter 5 for more detailed discussion on
soil settlement and bearing
capacity theory respectively.
March 2009
9-1