Effect of sample size on consolidation of a fissured clay

Abstract

This paper describes an experimental investigation on the effect of sample size on consolidation characteristics of fissured London Clay. Pore pressure dissipation tests on 38, 100, and 300 mm diameter samples were undertaken in the laboratory. Constant-head in situ permeability tests were conducted in four boreholes at different depths in the clay. Conventional oedometer tests on 76 mm diameter samples recovered from the same depths at which in situ permeability tests were carried out were also undertaken. The results show that both the coefficient of compressibility mv and the coefficient of consolidation determined in the laboratory are not significantly affected by sample size. It is concluded that estimate of in situ coefficient of consolidation can best be made from mv determined in the laboratory, and from in situ permeability measurements. Key words: consolidation, compressibility, fissured clay, permeability, size effect, testing.