A new approach to the debate between hypotheses A and B based on the isotache concept

¹ Faculty of Engineering, Hokkaido University, Sapporo, Japan
² Department of Civil Engineering, National Defense Academy, Yokosuka, Japan

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Consolidation settlement of an in-situ clay layer with a thickness of several meters to several tens of meters is generally predicted based on laboratory test results obtained from small specimens with a thickness of only 20 mm. Therefore, the similitude law with respect to layer thickness is of critical importance. This issue is directly related to the well-known debate between Hypothesis A and Hypothesis B. Against this background, the first author previously proposed a constitutive model describing the isotache law, in which the stress – strain relationship is uniquely determined as a function of strain rate in consolidation behaviour. The model is formulated using the consolidation yield stress as a key parameter and is essentially equivalent to the overstress power-law creep model. A simple finite-difference algorithm for practical uncoupled analysis was presented, in which compressive behaviour governed by the isotache law is solved using the temporal dissipation of excess pore water pressure. Furthermore, parametric analyses were conducted for various layer thicknesses, taking into account the initial effective stress distribution with depth due to the self-weight of the clay. The influence of layer thickness on consolidation settlement behaviour is discussed in relation to the debate between Hypothesis A and Hypothesis B.