The method chosen for improving slope stability depends on many factors,
including type or projected type of slope failure, soil characteristics and
site constraints. Frequently, more than one mitigation technique is
required. Typical slope mitigation techniques that are used include:
Drainage Improvements - Since water is the biggest culprit
in failing slopes, drainage improvements should be the first priority. Some
drainage improvements may include:
- Collect or divert surface water from the problem slope. This may
include catch basins, swales or sealing tension cracks to prevent
- Collect and remove subsurface water. This may include drains
constructed within the subsurface to remove excess seepage, or lower
Earthwork - The steeper the slope, the more prone it is to
fail. Some earthwork mitigation techniques are as follows:
- Remove the upper soils of the slope to create a flatter slope. This
is frequently done for existing landslides.
- Buttress the slope toe by filling with rock, gravel or soil.
- Benching the slope if each bench is on competent subgrade.
Structural Improvements - Structural improvements include:
- Mechanically Stabilized Earth (MSE)
- Retaining walls.
- Soil nailing
- Tie backs
- Reticulated micropiles
- Piles or drilled shafts
These days, slope stability analyses are usually performed via software
using an appropriate method for the specific site conditions.
Bishop's Simplified Method and Method of Slices considers a
circular failure surface. Janbu's Simplified Method and Spencer's
Method account for both circular and non-circular failure surfaces.
Morgenstern-Price Method is completed for non-circular slip planes only.
Two different theories with equations are provided here on the
slope stability analysis guidance document. These equations
provide a good overview of the factors that resist slope movement, and the
forces that induce landslides.
slope stability analysis
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