Civil Engineering Reference
In-Depth Information
FIGURE 9.29
Shear strength and mobilized shear along the base of each slice for the weakening slope sta-
bility analysis (
r
u
1.0). The SLOPE/W computer program was used to generate the plot (Geo-Slope 1991).
earthquake. Figures 9.26 and 9.30 show that a significant portion of the slope will be sus-
ceptible to a flow slide during the design earthquake. This slope will thus require mitiga-
tion measures in order to prevent a flow slide from developing during the design
earthquake. Mitigation measures are discussed in Sec. 9.7.
For this example problem, if the factor of safety were greater than 1.0, then a flow slide
would not occur during the design earthquake. However, because of the zone of liquefac-
tion, it is likely that there could still be lateral spreading of the slope. Section 9.5 discusses
lateral spreading.
9.4.4
Liquefied Shear Strength
It has been stated that the shear strength of liquefied soil may not necessarily be equal to
zero. For example, even though the soil liquefies, there may still be a small undrained shear
strength caused by the individual soil particles trying to shear past one another as the flow
slide develops. This undrained shear strength of liquefied soil has been termed the
liquefied
shear strength
(Olson et al. 2000).
