The permeability of natural soft clays. Part II: Permeability characteristics

The permeability characteristics of a number of intact natural soft clays from Québec, the USA, and Sweden have been investigated in the laboratory. The variation of permeability with void ratio is best represented in terms of a linear e vs. lg k relation which is generally valid in the range of volumetric strains encountered in engineering practice.The permeability at the in-situ void ratio is shown to be a complex function of such parameters as the void ratio, the clay fraction, the plasticity index, and the fabric of the clay. Permeability anisotropy is negligible in marine clays.The e vs. lg k relationships of the various clays tested are well ordered in terms of an empirical parameter (I P + clay fraction), irrespective of the geological origin of the clay. The slope of the e vs. lg k relationship, referred to as permeability change index C k , is simply related to the initial void ratio by C k = 0.5e o . Keywords: permeability, clays, laboratory tests, permeability anisotropy, permeability – void ratio relations.