Studying the development characteristics of cracks in expansive soil under the effect of dry-wet cycles is crucial for understanding the deformation and failure mechanism of expansive soil channel slopes. Addressing the current research limitations, an experiment on expansive soil crack development focusing solely on dry-wet cycles is conducted. Utilizing the block discrete element method based on the crack development pattern in expansive soil, a deformation analysis of expansive soil channel slopes is performed through programming. The study yields the following findings: (1) Water evaporation in expansive soil undergoes a transition from initial evaporation to stable evaporation, followed by deceleration rate evaporation and residual evaporation phases. (2) As the number of wet and dry cycles increases, the area ratio of expansive soil cracks gradually increases and then tends to stabilize. The total length of cracks increases progressively, while the average width of cracks continuously decreases and gradually stabilizes, and the angle between cracks transitions from T-shaped to Y-shaped. (3) The distribution of soil particles always develops towards a stable direction, the stress distribution between particles develops towards a more advantageous state, and the distribution of expansion and contraction cracks gradually stabilizes. (4) Applying the block discrete element method to analyze expansive soil slopes has successfully integrated the displacement and stress fields, taking into account cracks and hygroscopic expansion. (5) The wet-dry cycle effect accelerates crack development, with higher crack rates resulting in increased slope deformation, expansion of the plastic zone, and significant deformation at the base of expansive soil slopes.

Deformation and failure of the talus slope in the cold region significantly threaten engineered structures. Its driving mechanism of the deformation process is the most challenging issue. In this study, we try to explore these issues using tree ring characteristics. Fifty samples from 21 trees of Pinus densiflora growing on the talus slope in the Huanren area of Northeast China are tested to investigate the characteristics of tree rings and their relation to climate change. The deformation and its driving mechanism of this talus slope are then studied by combining the analysis of tree-ring width and mutation identification with the local meteorological data. The results present that the studied talus slope in Huanren has deformed to varying degrees at least 60 times since 1900. It is reasonable to speculate that the deformation mode of this slope is probably of a long-term and slow type. The local precipitation and seasonal temperature difference are the vital inducing factors of the mutation of tree-ring width and slope deformation. Repeated freezing and thawing are believed to be the driving factors of this talus slope in the cold region. A theoretical model is proposed to capture and predict the deformation of the talus slope. This work presents a new perspective and insight to reveal the deformation and its driving mechanism of similar talus slopes in the cold region. It is of great significance to practical engineering treatment and disaster prevention for this kind of cold region environment.

The most common type of natural disaster is a landslide which impact millions of people and costing tens of thousands of lives and billions of dollars in damage every year. Earthquakes have the potential to trigger landslides of varying sizes in mountainous regions, endangering the residential communities situated at the base of the mountains. The earthquake impact on the slope stability during the subsequent rains is not considerable in certain regions where the earthquake impact is not high enough to produce major soil movement. However, in some Landslide prone regions, the stability of slopes that are impacted by subsequent rains is significantly influenced by massive fissures on the surface of the slopes that are generated by earthquake shaking. The coupling effect of these two factors can significantly reduce the stability and safety of slopes, leading to catastrophic consequences. This paper reviewed the response of slopes under the combined influence of rain and seismic loading. This critical review highlights the importance of integrating rainfall and earthquake parameters simultaneously in slope deformation studies. In addition to slope stability analysis, slope deformation analysis should also receive equal attention. Future directions of this research should be focused on developing robust models and algorithms to simulate and assess slope failures caused by earthquakes and heavy rainfall in light of technological advancements, improvement of computational efficiency.

In deglaciating environments, rock mass weakening and potential formation of rock slope instabilities is driven by long-term and seasonal changes in thermal- and hydraulic- boundary conditions, combined with unloading due to ice melting. However, in-situ observations are rare. In this study, we present new monitoring data from three highly instrumented boreholes, and numerical simulations to investigate rock slope temperature evolution and micrometer-scale deformation during deglaciation. Our results show that the subsurface temperatures are adjusting to a new, warmer surface temperature following ice retreat. Heat conduction is identified as the dominant heat transfer process at sites with intact rock. Observed non-conductive processes are related to groundwater exchange with cold subglacial water, snowmelt infiltration, or creek water infiltration. Our strain data shows that annual surface temperature cycles cause thermoelastic deformation that dominate the strain signals in the shallow thermally active layer at our stable rock slope locations. At deeper sensors, reversible strain signals correlating with pore pressure fluctuations dominate. Irreversible deformation, which we relate with progressive rock mass damage, occurs as short-term (hours to weeks) strain events and as slower, continuous strain trends. The majority of the short-term irreversible strain events coincides with precipitation events or pore pressure changes. Longer-term trends in the strain time series and a minority of short-term strain events cannot directly be related to any of the investigated drivers. We propose that the observed increased damage accumulation close to the glacier margin can significantly contribute to the long-term formation of paraglacial rock slope instabilities during multiple glacial cycles.