deep foundation

2. DEEP FOUNDTION
GROUP MEMBERS:
SASHA HAMEED ( 2011-AE-32)
FATIMA ANSARI (2011-AE-13)
AFRAH TAHIR (2011-AE-04)
MUNZAR BASHIR (2011-AE-17)

3. DEEP FOUNDATION

4. DDEEFFIINNIITTIIOONN
 If the depth of a foundation is greater than its
width, the foundation is known as deep
foundation.
 In deep foundation the depth to width ratio is
usually greater than 4 to 5.
 Deep foundations as compare to Shallow
foundations distribute the load of the super structure
vertically rather than laterally.
 Deep foundations are provided when the expected loads
from superstructure cannot be supported on shallow
foundations.

5. EExxaammpplleess ooff DDeeeepp FFoouunnddaattiioonnss
 Pile foundations
 Pier foundations
 Wells or
Caissons foundations.

6. WWHHEENN IITT IISS UUSSEEDD??
 In cases where
 The strata of good bearing capacity is not available
near the ground
 The space is restricted to allow for spread footings
 In these cases the foundation of the structure has
to be taken deep with the purpose of attaining a
bearing stratum which is suitable and which
ensures stability and durability of a structure.
 The bearing stratum is not the only case. There
may be many other cases. For example, the
foundation for a bridge pier must be placed below
the scour depth, although suitable bearing stratum
may exist at a higher level.

7. TTYYPPEESS OOFF DDEEEEPP FFOOUUNNDDAATTIIOONN
Deep foundation is classified into following types:
• Pile foundation
• Well foundation
• Caisson foundation

8. PPiillee FFoouunnddaattiioonnss
 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
1. The piles 2. The pile caps

9. CCOONNTT’’DD
 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.
 Pile caps are thick slabs
used to tie a group of piles
together to support and
transmit column loads to
the piles.

10. PPiillee FFoouunnddaattiioonnss
 Where Used :
 stratum of required bearing capacity is at greater
depth
 steep slopes are encountered
 Compressible soil or water-logged soil or soil of
made-up type
 Examples: Piles are used for foundation for buildings,
trestle-bridges and water front installations (piers, docks
etc ).

11. TTyyppeess ooff PPiilleess BBaasseedd oonn FFuunnccttiioonn
Classification based on Function or Use
1. End Bearing Piles
2. Skin Friction Piles
3. Compaction Piles
4. Driven Piles
5. Auger cast Piles

12. TTyyppeess ooff PPiilleess (ccoonntt’’dd)
End Bearing Piles
 Driven into the ground until
a hard stratum is reached.
 Acts as pillars supporting
the super-structure and
transmitting the load to the
ground.
 Piles, by themselves do not
support the load, rather
acts as a medium to
transmit the load from the
foundation to the resisting
sub-stratum.

13. TTyyppeess ooff PPiilleess (ccoonntt’’dd)
Skin Friction Piles (Floating Piles)
 Piles are driven at a site where soil is
weak or soft to a considerable depth
and it is not economical or rather
possible to rest the bottom end of the
pile on the hard stratum,
 Load is carried by the friction
developed between the sides of the
pile and the surrounding ground
( skin friction).
 The piles are driven up to such a
depth that skin friction developed at
the sides of the piles equals the load
coming on the piles.
 The load carrying capacity of friction
pile can be increased by-
 increasing diameter of the pile
 driving the pile for larger depth
 grouping of piles
 making surface of the pile rough

14. TTyyppeess ooff PPiilleess ((ccoonntt’’dd))
Anchor Piles
 Piles are used to provide anchorage against horizontal
pull from sheet piling wall or other pulling forces.
Compaction piles:
 When piles are driven in granular soil with the aim of
increasing the bearing capacity of the soil, the piles are
termed as compaction piles.

15. TTyyppeess ooff PPiilleess ((ccoonntt’’dd))
Driven piles:
 Driven piles are deep
foundation elements
driven to a design depth.
If penetration of dense soil
is required, pre drilling
may be required for the
pile to penetrate to the
design depth. Types
include timber, pre-cast
concrete, steel H-piles,
and pipe piles.

16. TTyyppeess ooff PPiilleess ((ccoonntt’’dd))
• Auger cast piles
Auger cast piles, are deep
foundation elements that are
cast-in-place, using a hollow
stem auger with continuous
flights. The auger is then
slowly extracted, removing
the drilled soil/rock..
Reinforcing steel is then
lowered into the wet concrete
or grout. The auger is drilled
into the soil or rock to design
depth. The technique has
been used to support
buildings, tanks, towers and
bridges.

17. WWeellll ffoouunnddaattiioonnss
Well foundations are
being used in India
from very early
days.
Taj Mahal was
built on such
foundations. Wells
are also type of
deep foundations.
The main difference
between a well and
a pile foundation is
that, while a pile is
flexible like a beam
under horizontal
loads, the well
undergoes rigid
body movement
under such loads.

18. TTyyppeess ooff WWeellll
FFoouunnddaattiioonn
Wells have different
shapes and accordingly
they are named as
• Circular Wells
• Dumb bell
• Double-D Wells
• Double Octagonal Well
s
• Single and Double
Rectangular Wells
• Multiple Dredged
Holed Wells

19. LLOOAADDSS FFOORR WWEELLLL FFOOUUNNDDAATTIIOONN
DDEESSIIGGNN
The following loads are considered
for the analysis and design of well
foundation:
1.Dead load
2.Live load
3.Buoyancy
4.Wind load
5.Horizontal force due to water
current
6.Centrifugal forces
7.Longitudinal forces
8.Seismic forces
9.Horizontal shear forces at
bearings due to longitudinal forces
and seismic forces
10.Forces due to tilt and shift.

20. TTYYPPEESS OOFF FFOOUUNNDDAATTIIOONN
CCaaiissssoonnss
 Caisson foundation is also
known as pier foundation.
 Caisson is a cylinder or hollow
box that is sunk into the
ground to a specified depth by
auguring a deep hole into the
strata. The cylinder or box is
then back filled with concrete,
thus creating the foundation.
 This type of foundation is
most often used when
constructing bridge piers and
other such foundations that
will be beneath bodies of
water since the caissons can
be floated to the correct
locations and then sunk in
place using concrete.

21. WWhhyy TToo UUssee aa CCaaiissssoonn FFoouunnddaattiioonn
This type of foundation will keep the soils
underneath the building or structure from
moving vertically. Since soil will settle over
time, the building or structure on top of the soil
will also settle. This can cause major structural
damage. Since a caisson foundation is drilled
into the earth and large concrete t filled
cylinders are placed within the ground rather
than on top, the settlement of the soil will not
cause many difficulties for the building or
structure.

22. TTyyppeess ooff CCaaiissssoonnss
• Box caissons are
watertight boxes that
are constructed of
heavy timbers and
open at the top. They
are generally floated to
the appropriate
location and then sunk
into place with a
masonry pier within it.
• Excavated caissons are
just as the name
suggests, caissons that
are placed within an
excavated site. These
are usually cylindrical
in shape and then back
filled with concrete.

23. TTyyppeess ooff CCaaiissssoonnss ((ccoonntt’’dd))
• Floating caissons are
also known as floating
docks and are
prefabricated boxes
that have cylindrical
cavities.
• Open caissons are
small cofferdams that
are placed and then
pumped dry and filled
with concrete. These
are generally used in
the formation of a
pier.
• Pneumatic caissons
are large watertight
boxes or cylinders that
are mainly used for
under water

24. GGEEOOTTEECCHHNNIICCAALL DDEESSIIGGNN
OOFF DDEEEEPP FFOOUUNNDDAATTIIOONN

25. Careful study of loads to be transmitted
from columns of super structure and soil
profile.
OObbjjeeccttiivvee ::
o To identify type of pile
o To determine load carrying capacity
of individual pile
Only one type of pile below different
columns
For large projects two or three sizes may
be adopted

26. Study soil profile
Look for strong bearing layer
IF STRONG BEARING LAYER IS FOUND
Locate pile tip, a few meters, in
Pile becomes ‘end bearing pile’
Easy to conduct settlement analysis
11. IIDDEENNTTIIFFYYIINNGG SSTTRROONNGG
BBEEAARRIINNGG LLAAYYEERR FFOORR LLOOCCAATTIINNGG
TTHHEE PPIILLEE TTIIPP

27. IF NO STRONG BEARING LAYER IS
FOUND
Pile should be friction pile.
Pile derives its capacity from both, end
bearing & friction.
Select two pile lengths as deep as
possible.

28. Choice of pile depends on
Length
Width
Material ( concrete, steel, wood)
Cross-section (square, circular, tubular)
Installation procedure (driven, bored)
Feasibility of construction
Feasibility of noise and vibration
22.. SSEELLEECCTTIIOONN OOFF PPIILLEE

29. LENGTH :
Usually 10 – 30 m
Offshore application 70 – 100 m
WIDTH/DIAMETERS :
Usually 0.3 – 0.75 m
Drilled piles 1 – 2.5 m
Micropiles 0.15 m
33.. RRAANNGGEE OOFF PPIILLEE LLEENNGGTTHH &&
DDIIAAMMEETTEERRSS

30. Pile type – selected
Range of dimensions – chosen
Estimate the axial capacity
One of the procedures is ‘PPiillee LLooaadd TTeesstt’
4. AXIAL CCAAPPAACCIITTYY AANNAALLYYSSIISS

31. For piles, not resting on strong bearing
capacity, settlement analysis is
conducted.
55.. SSEETTTTLLEEMMEENNTT AANNAALLYYSSIISS

32. Presented in tabular form.
In selecting from the options available, two
factors are given :
Large sized but fewer number of piles,
hence installation time is less.
3 piles (min. number) can support only
lightly loaded columns, for heavier loads,
increase the pile group.
66.. RREESSUULLTTSS &&
RREECCOOMMMMEENNDDAATTIIOONNSS

34. AADDVVAANNTTAAGGEESS OOFF DDIIFFFFEERREENNTT
MMEETTHHOODDSS OOFF DDEEEEPP FFOOUUNNDDAATTIIOONN
DRILLED PIER FOUNDATIONS
Advantages
1.Pier of any length and size can be constructed at
the site
2. Construction equipment is normally mobile and
construction can proceed rapidly
3. Inspection of drilled holes is possible because of
the larger diameter of the shafts
4.The drilled pier is applicable to a wide variety of soil
conditions
5.Changes can be made in the design criteria during
the progress of a job
7.Ground vibration that is normally associated with
driven piles is absent in drilled pier construction
8.Bearing capacity can be increased.

35. DDiissaaddvvaannttaaggeess
1. Installation of drilled piers needs a
careful supervision and quality control of all
the materials used in the construction
2. The method is cumbersome. It needs
sufficient storage space for all the
materials used in the construction.

36. AAuuggeerreedd PPiilleess
Advantages……
1.Limited risk of damage to adjacent foundations or underground
utilities from ground displacement or densification of loose sands,
as can occur with displacement piles.
2.CFA piles can be installed with little vibrations or noise.
3.Should problems occur during pile construction, it is relatively
simple to re–drill and install the pile at the same location, thereby
eliminating the need to redesign the pile group or the pile caps.
4.A reliable flow meter can be used to monitor and record
penetration / uplift per revolution, auger depth, concrete supply
per increment of auger uplift during placing, and injection pressure
at the auger head.
.

37. DDiissaaddvvaannttaaggee
1.If the appropriate installation procedures are not followed exactly
the pile formed may be of poor and/or inconsistent quality and
load carrying capacity.
2.The most critical factor for the CFA system is still its reliance on
operator performance, which may result in a pile of poor quality
and reduced load carrying capacity. Thus, it is vitally important
that experienced personnel install the piles.
3.To ensure success it is vital to give due care to every stage of
the field installation procedure, including drilling of the hole,
casting of the shaft, extraction of the auger and the placement of
the reinforcement.

38. DDrriivveenn ccoonnccrreettee ppiillee
ADVANTAGES……..
1.Driven concrete pile foundations are applicable
under most ground conditions.
2.Concrete piles are usually inexpensive compared
with other types of deep foundations.
3.The procedure of pile installation is
straightforward; piles can be produced in mass
production either on site or in a manufacture
factory, and the cost for materials is usually much
less than steel piles.
4.Proxy coating can be applied to reduce negative
skin friction along the pile.
5.Pile driving can densify loose sand and reduce
liquefaction potential within a range of up to three
diameters surrounding the pile.

39. DDIISSAADDVVAANNTTAAGGEESS…………
1.Pile driving produces noise pollution and causes
disturbance to the adjacent structures.
2. Driving of concrete piles also requires large
overhead space.
3.Piles may break during driving and impose a
safety hazard.
4.Piles that break underground cannot take their
design loads, and will cause damage to the
structures if the broken pile is not detected and
replaced.
5. End-bearing capacity of a pile is not reliable if
the end of a pile is smashed.

40. DDRRIIVVEENN WWOOOODDEENN PPIILLEE
ADVANTAGES……
1.The piles are easy to handle
2.Relatively inexpensive where
timber is plentiful.
3.Sections can be joined together
and excess length easily
removed.

41. DISADVANTAGES
1.The piles will rot above the ground water level. Have a limited
bearing capacity.
2.Can easily be damaged during driving by stones and boulders.
3.The piles are difficult to splice and are attacked by marine
borers in salt water.

42. DDRRIILLLLEEDD SSHHAAFFTT MMEETTHHOODD
ADVANTAGES…….
1.The length and size of the foundations can be
tailored easily.
2. Disturbance to the nearby structures is small
compared with other types of deep foundations.
3.Drilled shafts can be constructed very close to
existing structures and can be constructed
under low overhead conditions. Therefore,
4. drilled shafts are often used in many seismic
retrofit projects.

43. DDIISSAADDVVAANNTTAAGGEESS
1. Drilled shafts may be difficult to install
under certain ground conditions such as soft
soil, loose sand, sand under water, and soils
with boulders.
2. Drilled shafts will generate a large volume of
soil cuttings and fluid and can be a mess.
Disposal of the cuttings is usually a concern
for sites with contaminated soils.
3. Drilled shaft foundations are usually
comparable with or more expensive than
driven piles.

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