You have full access to this open access article. This paper presents a constitutive model that predicts the water retention behaviour of compacted clays with evolving bimodal pore size distributions. In line with previous research, the model differentiates between the water present inside the saturated pores of the clay aggregates the microstructure and the water present inside the pores between clay aggregates the macrostructure.
A new formulation is then introduced to account for the effect of the macrostructural porosity changes on the retention behaviour of the soil, which results in a consistent evolution of the air-entry value of suction with volumetric deformations. Data from wetting tests on three different active clays i.
MX bentonite, FEBEX bentonite, and Boom clay , subjected to distinct mechanical restraints, were used to formulate, calibrate, and validate the proposed model. Results from free swelling tests were also modelled by using both the proposed double porosity model and a published single porosity model, which confirmed the improvement in the predictions of degree of saturation by the present approach. The proposed retention model might be applied, for example, to the simulation of the hydromechanical behaviour of engineered bentonite barriers in underground nuclear waste repositories, where compacted active clays are subjected to changes of both suction and porosity structure under restrained volume conditions.
Compacted active clays are used for the construction of engineered barriers in underground nuclear waste repositories, where they are subjected to complex thermohydromechanicalโchemical processes. This includes exposure to wetting from the saturated host rock and drying from the hot nuclear spent fuel [ 48 ], which makes the characterisation of the water retention behaviour of these materials particularly important.
The water retention behaviour of clays is also relevant to other applications including, for example, the prediction of settlements under superficial foundations, the study of groundwater flow and the design of agricultural irrigation systems [ 3 , 44 , 69 ]. Early retention models have proposed a unique relationship between degree of saturation and suction, thus disregarding the effect of porosity on soil water content e. Nevertheless, experiments published in the literature e.
