Geology Reference
In-Depth Information
◗
Figure 11.29
Rock Bolts and Wire Mesh Help Reduce Landslides
Stable bedrock
Rock bolts
Unstable rock layers
Rock bolts secured in bedrock can help stabilize a slope and
reduce landslides.
a
Rock bolts and wire mesh are used to secure rock on a steep
hillside in Brisbane, Australia.
b
Chapter Summary
movement (falling, sliding, or fl owing), and type of mate-
rial (rock, soil, or debris).
Rockfalls are a common mass movement in which rocks
free-fall. They are common along steep canyons, cliffs,
and road cuts.
Two types of slides are generally recognized. Slumps are
rotational slides that involve movement along a curved
surface and are most common in poorly consolidated or
unconsolidated material. Rock slides occur when move-
ment takes place along a more or less planar surface, and
they usually involve solid pieces of rock.
Several types of fl ows are recognized on the basis of their
rate of movement (rapid versus slow), type of material
(rock, sediment, or soil), and amount of water.
Mass wasting is the downslope movement of material
under the direct infl uence of gravity. It frequently results
in loss of life, as well as millions of dollars in damage
annually.
Mass wasting occurs when the gravitational force acting
on a slope exceeds the slope's shear strength (the resisting
forces that help maintain slope stability).
The major factors causing mass wasting include
slope angle, weathering and climate, water content,
overloading, and removal of vegetation. It is usually
several of these factors in combination that result in
slope failure.
Mass movements are generally classifi ed on the basis
of their rate of movement (rapid versus slow), type of
■
■
■
■
■
■
■
Search WWH ::
Custom Search