Natural and Artificial Unsaturated Soil Slopes

Recently, there have been extensive studies on engineering problems involving soils whose mechanical and hydraulic properties are strongly influenced by the degree of saturation. Earthen embankments, soil–vegetation–atmosphere interactions, geoenvironmental applications, and risk mitigation are just a few examples of the constant interest of the scientific community to the subject. The presence of a sloping ground surface is common to many of these problems. In slightly inclined natural slopes, susceptible to deep landslides, the unsaturated condition of shallow soil horizons affects deep pore water pressure distribution and, consequently, the stability of the entire slope. The stability of steep mountain areas covered by shallow deposits is often guaranteed by a shear strength contribution related to the unsaturated nature of the soil. In this case, the degree of saturation plays a key role in determining which rainfall events can act as landslide triggers, therefore controlling the post-failure evolution. Partial saturation is the basic characteristic of soils adopted as construction materials of geo-structures such as levees, dikes, and dams. This condition governs the structure behavior during construction phases, in serviceability, and in extreme scenarios. Hoping to provide a bridge between theoretical research and practical applications, this Special Issue collects quality contributions related to natural and artificial slopes under unsaturated conditions, and focuses on several aspects, including: water retention and transport properties, mechanical behavior, advances in experimental methods, laboratory and in situ characterization, soil improvement, field monitoring, geotechnical and geophysical field tests, landslide investigation and prevention, the design and maintenance of engineered slopes, analysis at different spatial scales, and the constitutive and numerical modeling of chemo-hydro-mechanical behavior.