Slopes Flashcards
What causes slope failure
when natural conditions and/or human-induced conditions caused a change in the forces that act at the slope area
This type of movement is known as Slope Failures or Landslides or just Slides
What natural conditions can cause slope failure?
Earthquake
Erosion
A general slope weakening because of the cracks’ development
A change in the elevation of ground water table
What human induced conditions can cause slope failure?
Increased loading on a slope or near its crest
Removal of earth below the toe of a slope
Removal of material from a slope so as to make it
steeper
Define: Cut slopes
slopes that are those made by an excavation. They expose natural ground that was once buried
Define: Fill Slopes
slopes made by placing fill
Define: Natural Slopes
slopes that are part of the natural topography
Define: Slope Ratio
Describes the steepness of a slope, always expressed as horizontal to vertical H:V
Define: top of slope/toe of slope
the point where the slope intersects flat ground
Define: slope face
the ground surface between the top of slope and toe of slope
Define: slope height
H, the difference in elevation between the top of slope and toe of slope (measured vertically, not diagonally along the face of the slope)
Define: terrace
a narrow area created in cut and fill slopes to accommodate surface drainage facilities
What is a rotational slide?
type of slope movement, a slide that moves along curved surfaces known as slip or failure surfaces
What is a translational slide?
type of slope movement, a slide along two planar surfaces
What is a block/wedge failure?
type of slope movement, refers to the displacement
of an intact mass of soil
because of the action of
an adjacent zone of earth
What is a “flow” type of slope movement?
-involves lateral down slope movement of soil
-when soil behaves like a viscous fluid, (although actual consistency may vary)
Flows differ from slides. They are
not well-defined blocks moving along shear surface.
What is a lahar?
a type of slope movement, a type of mudflow or debris flow composed of slurry, rocky debris, and water
-material flows down from a volcano, typically along a river valley
what is the failure/slip surface?
“failure surface” refers to the theoretical or actual surface within a soil or rock mass along which failure or instability occurs.
what is Limit Equilibrium Analysis (LEA)?
the quantitive analysis of
slides or potential slides
evaluate the slope as if it were about
to fail and determine the resulting shear
stress along the failure surface
Failure is indicated when moments causing motion exceed those resisting motion
What are the two types of rotational slides?
Spoon shaped
Cylindrical Shaped
safety factor =
Against sliding:
Safety factor=shear strength available/shear strength requried
With respect to LEA Method/Concepts
Safety Factor = moment resisting sliding/moment causing sliding
What is an acceptable safety factor (FS)?
For intact homogeneous soils, when the strength
parameters have been chosen on the basis of good
laboratory tests and careful estimate of pore
pressure has been made, a safety factor of at least
