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Expansive soils are widespread in the world and coincide with areas of high human activity. The main cause of deep instability of expansive soil slopes is due to their softening caused by excavation and seepage. By developing a comprehensive numerical model based on the theory of unsaturated soil, this study examines the characteristics of stress and displacement distribution of expansive soil slopes through hydraulic‐mechanical coupled numerical simulation. This study analyzes the evolution patterns of slopes with excavation unloading and seepage of water storage to reveal the mechanisms of deep‐seated instability of expansive soil slopes. The findings demonstrate that: The instability of expansive soil slopes begins at the foot of the slope and propagates along the interlayer, affecting the entire slope. Excavation leads to the softening of the expansive soil interlayer and the transfer of shear stress. During water storage, the weakening of the soil strength results in slope instability along the weak interlayer slip. Softening of the expansive soil interlayer facilitates the redistribution of shear forces in the slope and alters the distribution law of the plastic zone in the deep layer. Overly slowing down the slope leads to significant excavation unloading, which is detrimental to the slope's stability. [ABSTRACT FROM AUTHOR]

Swelling-shrinkage deformation of expansive soils is the primary governing factor for development of the crack network, which is intimately associated with the bearing capacity and the structural integrity of the soil body. To suppress the swelling-shrinkage characteristic, sintered red mud was utilized as a curing agent to stabilized expansive soil, and the physical property testing phase consisted of compaction tests, Atterberg limit tests and pH tests to derive patterns on the physical and mechanical properties of the expansive soil influenced by the incorporation of red mud. The principal engineering property tests include unconfined compressive tests, one-dimensional swell tests, desiccation-induced crack study and micro-structure analysis by scanning microscopy techniques. The test findings demonstrate that even red mud would somewhat weaken the strength, but restrict the plasticity and successfully prevent swelling-shrinkage deformation of expansive soils. Such an effect is positively correlated with the red mud content. When the content reaches 20%, the crack ratio reduction exceeds 40%, the swelling deformation are reduced by about 20%, and the unconfined compressive strength higher than 500 kPa with dry density of 1.6 g/cm3. The stabilization of expansive soils with red mud effectively increases the structural integrity of the soil layers and the safety of constructions to offer guidance for environmentally friendly construction in expansive soil areas. [ABSTRACT FROM AUTHOR]

Desiccation cracks are the most prevalent cause of engineering geological problems with expansive soils, and tensile strength is the major restricting component for crack formation and development. To promote the development of the connection between tensile strength and other mechanical indexes, a test procedure was established that can measure uniaxial tensile strength and unconfined compressive strength in the same conditions. Uniaxial tensile and compressive tests were performed on compacted expansive soils with water contents that varied from 12% to 24% and dry densities ranging from 1.4 g/cm3 to 1.6 g/cm3. The suction and pore surface fractal dimensions of the specimens were also measured. The experimental findings reveal that the uniaxial tensile strength and unconfined compressive strength followed similar trends as degree of saturation increases and are significantly reliant on suction variations. Then, tensile-compressive-strength ratio and pore surface fractal dimension are subsequently employed to develop tensile strength prediction models. The models presented above have specific physical implications that compensate for the limitations of the fitted models. Finally, the applicability and limits of suggested models for future applications are examined. [ABSTRACT FROM AUTHOR]

The management and knowledge of landfills are generally inadequate and could lead to significant catastrophes. This is particularly concerning for solid waste landfills due to their large size and potential to threaten nearby structures and residents in the event of landslides. In this paper, we investigated a backfill landslide induced by road construction in a coal mine slag landfill. Our analysis of satellite images and field surveys revealed that the alteration of the mounding morphology at the slope's crest by construction triggered the landslide. We established an engineering geological model of the main sliding plane and utilized the discrete-element program MatDEM to reproduce the landslide's development and predict its final accumulation pattern and impact range. Our study highlights the potential dangers of engineering construction carried out on relatively stable solid landfills. The combined in situ and numerical analysis research methods employed in this study can provide important references for risk assessment and treatment measures. [ABSTRACT FROM AUTHOR]