Geoscience Reference
In-Depth Information
Table 20.11 Use of the different factors of safety for a reinforced slope (Duncan and Wright, 1995).
Factor of safety using limit equilibrium
Application to
Comment
equation form
reinforcement design
Soil resisting moment
Allowable force
Preferable
Overturning moment
reinforcement moment
Soil resisting moment
+
reinforcement moment
Ultimate force
Divide by FS calculated
in analysis
Overturning moment
20.12 Soil slope facings
A facing is required on soil slopes depending on the batter.
A face protection is required to prevent erosion.
Table 20.12 Soil slope stabilisation.
Consideration
Wall type and facing required
Slope
1V: 0.01H
1V: 0.36H
1V: 1H
~1V:2H to 1V:1.7H
1V:2H
Typical slope angle
~90
70
45
φ
cv
φ
cv
Vertical
wall
Battered
wall
Design
Reinforced slope
Unreinforced slope
Type of facing
Active facing
Passive facing
No facing
Concrete,
Embedded
Gabion,
Crib
Geocells, Revetments, rock facings
Geomesh,
Wall type
Soil nail,
Reinforced
soil slope
Soil nail, Reinforced
soil wall
Vegetation
A soil nail process is a usually a top down process while a reinforced soil wall is
a bottom up construction.
Soil nails have some stiffness that can take up shear forces and bending moments
while reinforced earth strips are flexible.
20.13 Wall types for cuttings in rock
The wall types and facing required is dependent on the stability based on the joint
orientations.
If flattening the slope is not a feasible option at a given site then a facing unit and
wall is required.
 
 
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