Environmental Engineering Reference
In-Depth Information
(a)
FIGURE 9.1
Forms of falls in rock masses: (a) free fall and
(b) toppling by overturning.
(b)
3.
Intermediate failure stage : Progressive slumps and scarps begin to form during
rotational slides, and blocks begin to separate during planar slides, as tension
cracks grow in width and depth. Movement velocities may range up to about 2
in./day (5 cm/day), accelerating during rainy seasons and storms and dimin-
ishing during dry periods. Movement is affected also by flooding, high tides, and
earthquake forces. The slope is essentially intact and may remain in this condi-
tion for many years (see Figure 9.89) .
4.
Partial total failure : A major block or portion of the unstable mass has moved to a
temporary location leaving a large scarp on the slope ( Figure 9.25a) .
5.
Complete failure : The entire unstable mass has displaced to its final location (see
Figure 9.93) , moving rapidly at rates of about 3 ft/min (1m/min) for the case of
 
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