This work aims to investigate the micropore properties of saturated kaolin subjected to triaxial loading. Consolidated drained triaxial compression tests were conducted on both normally consolidated and overconsolidated clay specimens. In the (p′, q) plane, a given stress level was reached by following two different stress paths (i.e., the purely deviatoric stress path and the conventional constant σ′₃ stress path). This approach allows observing the influence of stress path on the evolution of pore structure. The experimental approach consisted in using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) to quantify the micropore structure of the specimens after being submitted to mechanical loading. The results clearly show that the micropore structure of clay was affected by the loading conditions. Consequently, the development of induced anisotropy appeared as mainly related to the variation of pore shape and pore orientation. Meanwhile, for overconsolidated specimens featuring dilative behavior, the pores exhibited a trend to be more open (i.e., rounder) and more randomly oriented compared with the normally consolidated specimens showing contractive behavior. Even if the micropore structures deduced from the SEM-based method, on the one hand, and from MIP tests, on the other hand, concern different scales of pores, the analysis shows that both methods of investigation were quite well comparable and revealed similar variation tendencies in void ratio and pore size distribution.

Tensile strength is an important soil parameter that affects the stability of structures built on clayey soils. This paper presents an experimental study of the change of tensile properties of red clay during wet-dry cycles. Cyclic wet-dry tests were performed on compacted red clay specimens with different initial water contents and dry densities. Direct tensile tests and Brazilian split tests were then conducted on these specimens to determine the soil strengths. The effects of initial water content, initial dry density, number of wet-dry cycles, and crack rate on the tensile properties of red clay were investigated. The results demonstrate that the tensile strength of red clay is generally 1.566 times the splitting strength. Both the tensile strength and splitting strength are negatively correlated with the initial water content but are positively correlated with the initial dry density. Because of the presence of desiccation cracks, the tensile strength goes on reducing under wet-dry cycles. The tensile strength can be expressed by a power function of the initial water content, initial dry density, and crack rate. The proposed equation is useful to evaluate the tensile strength of cracked soils subjected to wet-dry cycles.