Embankment dams, their zoning and selection - Geotechnical Engineering of Dams - page 326

Table 8.7. Types of embankment dams, their degree of control of internal erosion and piping, and pore pressures for stability, and suitability in relation to con-

sequences of failure classification.

Consequences of failure

Degree of filter control of Degree of control of pore classifications to which

Embankment type Description of the zones internal erosion and piping pressures for stability suited - new dams

Homogeneous Zone 1 earthfill None. Seepage in earthfill and Poor. Pore pressures not Very low and low

earthfill from cracks is likely to emerge on predictable. Depend on k H /k V

the downstream face regardless in earthfill

of k H /k V

Earthfill with toe Zone 1 earthfill, Zone 4 Poor. Seepage in earthfill Poor. Pore pressures not Very low and low

drain rockfill, may have Zone 2A/2B and from cracks is likely to emerge predictable. Depend on k H /k V

filter drain on the downstream face for high in earthfill

k H /k V . Poor into rockfill if no
filters provided

Zoned earthfill Zone 1 earthfill. Zones 1-3 of Moderate (poor to good). All Good provided Zones 1-3 is Very low to significant,

borrow pit run alluvial silt/ seepage will be intercepted by much higher permeability depending on material

sand/gravel; or weathered and Zones 1-3. Depends on particle than Zone 1 particle size

low strength rock, compacted size distributions of Zones 1-3 distributions and

to form silt/sand/gravel to act as a filter to Zone 1 construction control

Earthfill with Zone 1 earthfill. Zone 2A Poor. Seepage in earthfill and Poor. Pore pressures not Very low and low.

horizontal drain filter drain from cracks is likely to emerge on predictable. Depend on Significant if no

the downstream face for high k H /k V k H /k V in earthfill population at risk