The effect of compaction on bulk permeability of stiff clay and mudrock - field experience from embankment dams

The permeability of in-situ clays and soft mudrocks is strongly affected by slightly open fissures. These are difficult to discover from site investigation as the permeability of the parent intact material is very low. This is measured by laboratory tests and, often, by in-situ tests. It is difficult to prove the absence of open fissures and low bulk permeability. This causes uncertainty in the use of these materials as impermeable seals. However, field experience is that when these materials are placed as fills using modern plant, a uniform low permeability results. There is much experience in the construction of the cores and fills of embankment dams. This experience is reviewed.