Abstract: Natural sedimentary clays exhibit anisotropic consolidation properties since most clay minerals are platy and the clay particles and fabric elements tend to be horizontally oriented in the deposition and subsequent consolidation processes. In this paper, the anisotropic consolidation properties of Ariake clay in Japan were studied by the constant rate of strain (CRS) consolidation test using vertically and horizontally cut specimens. The test results show that the ratios of the preconsolidation pressure of horizontally cut specimen (pch) to that of vertically cut specimen (pcv) are in the range from 0.5 to 1.0, which is mainly due to the anisotropic yield locus of natural sedimentary clay and the different stress paths experienced by the vertically and horizontally cut specimens. In the normal consolidation range, the ratio of coefficient of consolidation obtained from horizontally cut specimen (ch) to that from vertically cut specimen (cv) is approximately 1.43, and the ratio of hydraulic conductivity obtained from horizontally cut specimen (kh) to that from vertically cut specimen (kv) is approximately 1.40, while the coefficient of volume compressibility obtained from horizontally cut specimen (mh) is approximately equal to that from vertically cut specimen (mv). Therefore, the anisotropy of coefficient of consolidation of Ariake clay mainly arises from the anisotropy of hydraulic conductivity, which is essentially induced by the anisotropy of microstructure.

Key words: anisotropy, consolidation behavior, clay, constant rate of strain (CRS)