Mata kuliah : S0892 – Ground Improvement Method
Tahun
: 2010
Slop Stabilization
Pertemuan 8 - 10
COURSE 3
Content:
• Problems On slope
• Stabilization Methods:
– Soil Nailing
– Retaining Wall
– Reinforcement
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PROBLEMS ON SLOPE
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SLOPE FAILURE
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FAILURE TYPE
• ROTATIONAL
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FAILURE TYPE
• TRANSLATIONAL
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FAILURE TYPE
• FALLING
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FAILURE TYPE
• BLOCK SLIDE
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FAILURE TYPE
• TOPPLE
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FAILURE TYPE
• FLOW
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PROBLEMS ON SLOPE
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STABILIZATION METHODS
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STABILIZATION METHODS
• SOIL NAILING
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SOIL NAILING
DEFINITION
• Soil nailing is a technique in which soil slopes, excavations or
retaining walls are reinforced by the insertion of relatively slender
elements - normally steel reinforcing bars.
• The bars are usually installed into a pre-drilled hole and then
grouted into place or drilled and grouted simultaneously.
• They are usually installed untensioned at a slight downward
inclination. A rigid or flexible facing (often pneumatically applied
concrete otherwise known as shotcrete) or isolated soil nail heads
may be used at the surface.
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SOIL NAILING
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SOIL NAILING
BASIC PRINCIPLE
• The basic concept of soil nailing is to reinforce and strengthen the
existing ground by installing closely spaced steel bars, called "nails,"
into a slope or excavation as construction proceeds from the "top
down."
• This process creates a reinforced section that is itself stable and
able to retain the ground behind it. The reinforcements are passive
and develop their reinforcing action through nail ground interactions
as the ground deforms both during and following construction.
• Nails work predominantly in tension, but are considered by some to
also work in bending/shear under certain circumstances.
• Generally, the soil nails significantly increase the apparent cohesion
of the soil through their ability to carry tensile loads.
• A construction facing is also usually required, and is typically
shotcrete reinforced by welded wire mesh. For permanent walls, the
shotcrete construction facing is typically covered in cast-in-place
concrete facing.
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SOIL NAILING
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SOIL NAILING
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SOIL NAILING
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SOIL NAILING
•
•
•
•
•
•
Nails work predominantly in tension but may develop bending/shear in certain
circumstances. The effect of the nail reinforcement is to improve stability by
(a) increasing the normal force and hence the soil shear resistance along
potential slip surfaces in frictional soils; and
(b) reducing the driving force along potential slip surfaces in both frictional and
cohesive soils. A construction facing is also usually required and is typically
shotcrete reinforced by welded wire mesh.
The steel nail bars are typically 20 to 35 mm in diameter, with a yield strength in the
range of 420 to 500 N/mm2, and are typically installed into drillholes having diameters
in the range of 100 mm to 300 mm and at a spacing between 1 and 2 meters.
The nail lengths are typically 70 to 100 percent of the wall height.
Nail inclinations are generally on the order of 15 degrees below horizontal to facilitate
grouting.
Soil nails typically consist of steel reinforcement inclusions and may be categorized
on the basis of their method of installation and degree of corrosion protection. For
conventional drill and grout nail installations, the nail grout consists typically of a neat
cement grout with a watercement ratio of about 0.4 to 0.5. Where a stiffer consistency
grout is required (e.g., to centralize the nail when no centralizers are used in a hollow
stem auger installation or to control leakage of grout into the ground such as in highly
permeable granular soils or highly fractured rock),
a lower slump sand-cement grout may be used. Sand-cement grout may also be
used in conjunction with large nail holes for economic reasons.
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SOIL NAILING
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SOIL NAILING
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SOIL NAILING – CONSTRUCTION
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SOIL NAILING – CONSTRUCTION
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SOIL NAILING – CONSTRUCTION
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SOIL NAILING – CONSTRUCTION
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SOIL NAILING – CONSTRUCTION
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SOIL NAILING – CONSTRUCTION
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SOIL NAILING – CONSTRUCTION
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RETAINING WALLS
A retaining wall is a structure that holds back soil or rock from a building, structure or
area. Retaining walls prevent downslope movement or erosion and provide support
for vertical or near-vertical grade changes
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RETAINING WALLS
Safety against sliding along the base
Fsliding 
PP  {Wi }. tan 
soil-concrete friction
angle  0.5 – 0.7 
PA
to
tobe
begreater
greater
than
than1.5
1.5
2
2
PA
H
3
3
1
PP
S
toe
h PP
1
S
R
toe
y
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PA
R
y
2
PPPP==0.5
0.5KKPPh
h2
2
PPAA==0.5
0.5KKAAH
H2
RETAINING WALLS
Safety against overturning about toe
Foverturning 
PP h / 3  {Wi xi }
PA H/3
to
tobe
begreater
greater
than
than2.0
2.0
2
2
PA
H
3
1
PP
S
toe
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3
h PP
R
y
1
S
toe
R
y
PA
RETAINING WALLS
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RETAINING WALLS
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RETAINING WALLS
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RETAINING WALLS
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RETAINING WALLS
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REINFORCEMENT
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REINFORCEMENT
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REINFORCEMENT
z
H
Sv
45 0+ /2
LE
LR
Lo
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REINFORCEMENT
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REINFORCEMENT
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REINFORCEMENT
OVERTURNING STABILITY, FS  2
SLIDING STABILITY, FS  1.5
BEARING CAPACITY STABILITY,
FS  3
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