Control of seepage, internal erosion and piping for embankment dams - Geotechnical Engineering of Dams - page 429

Figure 10.45. Internal cracking in embankments due to differential settlements (Sherard et al., 1963).

Table 10.9. Influence of factors on the likelihood of suffusion of cohension less soils (Foster and Fell,
2000).

Influence on likelihood of suffusion

Factor More likely Neutral Less likely

Particle size distribution:
- General Gap-graded Uniform gradation,

- Gap-graded soils Flat tail in finer sizes well graded

5 (2) 5 (2) (Sherard, 1979) d15c/d15f d15c/d15f

- Smooth gradations Potentially unstable Stable

with a tail of fines
based on Kenney and
Lau (1985) or
Burenkova (1993)
Compaction density Poorly compacted, 95-98% standard Well compacted,

95% standard Compaction density 98% standard

compaction density ratio compaction density

ratio (1) ratio

Permeability High Moderate Low

(1)

Notes: 93% Standard compaction, dry of OWC, much more likely.

(2) d15c

particle size on coarse side of the distribution for which 15% is finer, d15f particle

size on the fine side of the distribution for which 15% is finer.

Continuation of erosion is highly likely if there is no downstream filter e.g. in homoge-
neous dams.
The presence of well designed filters to control the continuation and progression of ero-
sion in the embankment and foundation can virtually eliminate the chances of piping.
However this is dependent on good detailing, with the filters intercepting all potential