Environmental Engineering Reference
In-Depth Information
Figure 11.10.
Deformation of eppalock dam (courtesy of Goulburn-Murray Water).
Figure 11.11.
Cracking and softening due to settlement and lateral spreading at the crest of an embank-
ment dam (courtesy Goulburn-Murray Water).
- Allowance for water pressures in these cracks;
-Averaging of the strength for failure surfaces which will pass through many layers of
the compacted soil, i.e. steeply sloping failure surfaces;
-
Adoption of the strength of lower strength layers for failure surfaces which are horizon-
tal. However care needs to be taken in this, since it is not usually likely that weak layers
will persist across the zone, unless they are due to desiccation or freezing in a prolonged
shut-down during construction or a particularly poor period in compaction control.
11.3.3
Inherent soil variability
When assessing the strength of materials for stability analysis it should be recognised that
there are inherent uncertainties in the strengths of the soil and there are potential errors in
the measurement of the strength and the formulae used to transform the measured value
(e.g. SPT “N” value or CPT q
c
value) to strength. This is discussed in Kulhawy (1992).
