9/17/2017

Permeability of a stiff fissured very high plasticity Palaeogene clay - direct and indirect measurement methods and scale effects

T.R. Simonsen & S.S. Gadegaard, Geo & K.K. Sørensen, Department of Engineering, Aarhus University

Abstract

Different methods of measuring the direct and indirect permeability of clays exists, both in the laboratory and in the field. However, traditionally the determination of permeability of heavily overconsolidated and stiff Danish Palaeogene clays often rely only on the oedometer test method, which is an indirect test method. However, this method has previously been shown to underestimate the in situ permeability of this type of clay. This paper explores the differences in permeabilities derived from indirect and direct permeability tests in the laboratory and the field through a series of oedometer tests, constant head permeability tests, rising head tests and CPTU dissipation tests. The results show that the indirect permeability tests yield the lowest permeabilities whereas the direct measuring methods yield only slightly higher permeabilities. Laboratory tests are prone to underestimate the in situ permeability of the clay due to the presence of macro structures.