Masaru Akaishi

A simple anisotropic clay plasticity model

Abstract An anisotropic clay plasticity constitutive model is extended to include a non-associative flow rule for the successful simulation of the response under undrained loading for some normally consolidated sensitive clays, including possible softening response, without altering otherwise the simple basic structure of the formulation. The model has been developed within the framework of critical state soil mechanics (CSSM) for the triaxial space. The models structure deviates, in general, from the particular premises of CSSM in regards to a unique critical state line in the space of void ratio and effective pressure, in order to simulate observed experimental data.

Long-term settlement behavior of soft grounds and secondary compression

Abstract Settlement–time behaviors in the last stage of consolidation are studied both in the laboratory and in the field. It is shown that the long-term settlement–time curves observed in the field are linear with the logarithm of time and the rate of the long-term settlement are analogous to the rate of secondary compression measured in a laboratory. The finite difference consolidation analyses for cohesive soils exhibiting large amounts of secondary compression during primary consolidation provide fairly good predictions of the settlement–time curves observed in the laboratory and in the field. In this paper, the applicability of the secondary compression model established in the laboratory is examined in in situ conditions. The initial rate of secondary compression used in this paper has a predominant influence on the settlement–time curve with different drainage distances. It is emphasized that the assumption for unknown secondary compression behaviors during the primary consolidation has a predominant influence on the settlement–time curve.

EFFECTS OF PLASTIC POTENTIAL ON THE HORIZONTAL STRESS IN ONE-DIMENSIONAL CONSOLIDATION

The coefficient of earth pressure at rest K_0 is obviously important in geotechnical problems. The influences of a plastic potential on the minor principal effective stress during one-dimensional consolidation are examined by finite element consolidation analysis. Results of experimental and numerical investigations indicate that the coefficient of earth pressure at rest during one-dimensional consolidation appears to be governed by the plastic potential and time effects of secondary compression.