Study on Strength Attenuation Characteristics of Residual Expansive Soil under Wetting-Drying Cycles and Low Stress and Its Relationship with Shallow Landslide

Abstract

The rapid development of expansive soil fissures and the attenuation of strength under the action of repeated atmospheric wetting-drying cycles have a very adverse impact on the shallow stability of expansive soil slope. In this study, shear strength test and fissure observation test were performed on typical residual expansive soil specimens at various wetting-drying cycles and low stress. The results show that the shear strength index of residual expansive soil should be obtained according to the high and low stress sections, respectively. The cohesion of the three residual expansive soils decreased to a similar low value range (0~5 kN) at multiple wetting-drying cycles and low stress; the attenuation of cohesion is the main cause of shallow slope collapse. The fissure rate of the specimen surface increases with the increasing number of wetting-drying cycles, and increasing the dry density can significantly inhibit the development of fissures. The repeated wetting-drying cycles leads to the rapid development of slope fissures from the surface to the inside, destroys the internal natural structure of undisturbed expansive soil, reduces the cementation between soil particles, and leads to the decrease of soil cohesion. For slope stability analysis of residual expansive soil, the strength parameters of the specimens with multiple wetting-drying cycles and internal fissure network should be selected according to the overburden pressure of the slope sliding surface. The research results provide a theoretical basis for the stability analysis of shallow landslide of expansive soil slope and slope protection design.

Effect of dry-wet alternation on the adsorption of dissolved organic matter by soil minerals

“…When moisture increases, montmorillonite exhibits more intense swelling in interaction with water. When moisture decreases, it shrinks in volume and produces fissures (Chang et al, 2022). Ilmenite has reversible contraction and expansion under wetting and drying conditions.…”

Microstructure and Mechanical Properties of Expansive Clay under Drying–Wetting Cycle

“…Cai et al [18] studied the fissure evolution law of canal slopes and deformation via two sets of expansive clay canal drying-wetting cycle centrifugal model tests; they examined the development of soil fissures and the law of canal water infiltration, and its influence on the deformation and stability of canal slopes under the action of such cycles. Using model tests and theoretical calculations on the stability of expansive clay slopes under the action of drying-wetting cycles, scholars worldwide have recognized that swelling and shrinkage, and fissure properties, as well as the action of drying-wetting cycles, are the main factors inducing the instability of expansive clay slopes [20][21][22].…”