The stability of loess high-fill slopes is a crucial issue in engineering, where the presence of fissures significantly impacts slope stability. This study investigates the seepage-mechanical response and fissure evolution characteristics of loess high-fill slopes under the coupled effects of consolidation, rainfall, and evaporation through model testing. The disaster chain evolution process of the slope under these coupled effects is revealed. The results show that the development of fissures in loess high-fill slopes does not follow a directional pattern and has a uniform influence on soil properties. Under rainfall, the slope exhibits preferential flow paths, which guide the deformation and failure modes. With the development of fissures, the fill material shows a cumulative damage effect, leading to progressive performance degradation and continuous decline in slope stability. This study enriches the theoretical framework for stability analysis of high-fill fissured slopes and provides guidance for disaster prevention and mitigation in loess regions.

In recent years, geological disasters on loess fill slopes have occurred from time to time, which has attracted widespread attention. In order to deeply understand its deformation and failure laws and promote the disaster prevention and mitigation work, this paper takes remolded loess as the research object, systematically explores the effects of three different stress paths (conventional triaxial compression test (CTC), triaxial compression test with constant average principal stress (TC), and triaxial compression test with reduced confining pressure (RTC)) on its mechanical properties, and observes and analyzes its microstructural characteristics by scanning electron microscopy (SEM). The results show that the soil is strain hardening under the CTC path, while it is strain weak hardening under the TC and RTC paths. In the order of CTC, TC, and RTC paths, the shear strength and volume shrinkage of the soil are reduced in turn, and its deformation has both shear reduction and shear expansion plastic deformation. In the order of CTC, TC, and RTC paths, the degree of particle crushing decreases in turn and the pore content increases in turn. It is inferred that in the initial deformation of loess under loading, the soil is compressed and compacted, and its strength is improved to a certain extent. As the loading continues to increase, the deformation rate increases steadily, and the soil deformation develops gradually, which is mainly axial compression deformation, while the lateral bulging deformation is small until it is destroyed. For the deformation behavior in the form of lateral unloading, the soil is maintained in a relatively stable state at the beginning, and the deformation is very small. When the lateral constraint is reduced to a critical state, the structure is completely unstable, and the deformation develops rapidly in a short time until it is destroyed. This study is of great significance for reducing the occurrence of geological disasters on fill slopes in loess areas.

Loess has high water sensitivity and exhibits poor characteristics such as weak cementation and high porosity. Under heavy rainfall, loess fill slopes are prone to erosion and landslides, posing serious threats to public safety and property. In light of these serious threats, this study employed the method of spraying polyvinyl alcohol (PVA) solution to improve loess fill slopes and systematically examine its protective effects. Through field investigations and combined laboratory and outdoor tests, this study comprehensively evaluated the mechanical properties, anti-aging and anti-erosion performance of loess after PVA solution spraying. Scanning electron microscopy was used to reveal the mechanism of PVA action at the microscopic level. The results showed that after treatment with PVA solutions of varying concentrations, the mechanical properties of loess samples were significantly enhanced, while also exhibiting excellent anti-aging and water resistance performance. Additionally, PVA-treated loess fill slopes exhibited excellent rain erosion resistance. A microscopic structural analysis showed that PVA fills the internal pores of loess, strengthens inter-particle bonding, and uses its hydrophobic groups' water-repellent action to effectively enhance slope stability and erosion resistance. In conclusion, PVA treatment not only significantly enhances the protective effects of loess fill slopes but also holds important value in improving soil sustainability and environmental protection.

The slope erosion in the distribution area of completely weathered granite is often relatively severe, causing serious ecological damage and property loss. Ecological restoration is the most effective means of soil erosion control. Taking completely weathered granite backfill soil as the research object, two types of slope protection plants, Vetiver grass and Pennisetum hydridum, were selected. We analyzed these two herbaceous plants' soil reinforcement and slope protection effects through artificial planting experiments, indoor simulated rainfall experiments, and direct shear tests. The test results showed that the runoff and sediment production rates of the two herbaceous plant slopes were significantly lower than those of the bare slope, with the order of bare slope > Vetiver grass slope > Pennisetum hydridum slope. Compared with the bare slope, the cumulative sediment production of the Vetiver grass slope at 60 min decreased by 56.73-60.09%, and the Pennisetum hydridum slope decreased by 75.97-78.45%. The indoor direct shear test results showed that soil cohesion decreases with increasing water content. As the root content of Vetiver grass roots increases, soil cohesion first increases and then decreases, reaching a maximum value when the root content is 1.44%. As the root content of Pennisetum hydridum increases, soil cohesion increases. The internal friction angle increases slightly with increasing water content, while the root content does not significantly affect the internal friction angle. Therefore, the shear strength of soil decreases when the water content increases. The shear strength of the Vetiver grass root-soil composite reaches a peak at a root content of 1.44%, while the shear strength of the giant king grass root-soil composite increases as the root content increases. At the same root content, the shear strength of the Vetiver grass root-soil composite is slightly higher than that of giant king grass. The reinforcement effect of roots on shallow soil is better than on deep soil. Both herbaceous plants have an excellent soil-fixing and slope-protecting impact on the fully weathered granite backfill slope. Pennisetum hydridum's soil and water conservation effect is significantly better than that of the Vetiver grass. In contrast, Vetiver grass roots slightly outperform Pennisetum hydridum in enhancing the shear strength of the soil. The research results can provide a theoretical basis for the vegetation slope protection treatment of fully weathered granite backfill slopes.

Quantitative assessment of landfill slope failure risk provides valuable information about slope design and risk reduction. This study presents a reliability-based analysis in which an accurate method is applied to assess slope failure risk using the stochastic finite difference method. This method incorporates the spatial variability of municipal solid waste properties due to anisotropic autocorrelation structures and evaluates the consequence associated with each failure separately. This method was evaluated using the data of the Saravan landfill (Rasht, Iran) and presenting a parametric analysis. Several Monte Carlo simulations were conducted to indicate the heterogeneity of the municipal solid waste, taking into account the shear strength and the unit weight of the municipal solid waste randomly. Finally, the safety factor, probability of failure, and risk were assessed using different analysis cases. Deterministic analysis was also performed for all modes using mean values for various municipal solid waste properties. The results show that spatial variability of municipal solid waste parameters and autocorrelation structures significantly affect the safety factor, probability of failure, and risk. Also, comparing the obtained results revealed that for the given slope, the safety factor values in deterministic analyses are overestimated compared to those of the probabilistic analyses. However, risk shows the opposite behavior.

Heavy or intermittent rainfall can cause slopes to become unstable and erode, resulting in significant damage, loss of life, and destruction of property. Targeted management solutions are based on an analysis of slopes' flow generation and sediment production patterns during periods of rainfall. This study used a fully granite backfill slope as its research subject and examined the features of slope erosion during intermittent rainfall. We examined the processes of slope flow generation and soil erosion during intermittent rain through indoor artificially simulated rainfall experiments. Three intermittent rainfall events with a 220 mm/h intensity were designed during the experiment. Each rainfall event lasted for 60 min, with an interval of 60 min between the events. By analyzing multiple rainfall events, this study reveals the patterns of runoff and sediment yield on different slopes in response to variations in rainfall intensity and slope gradient. The runoff volume on other slope surfaces exhibits a similar pattern in reaction to changes in rainfall events. As the frequency of rainfall events increases, the surface runoff tends to be higher. Additionally, with variations in slope steepness, the runoff volume generally follows an increasing trend. Notably, the slope with a 20 degrees incline shows the smallest runoff volume. The sediment yield on different slope surfaces gradually increases as the slope increases. In particular, on a 20 degrees slope, the sediment yield experiences a substantial increase, indicating that the impact of the slope on the sediment yield becomes more pronounced. In different rainfall events, the morphology of the slope changes due to the influence of gravity and hydraulics, resulting in oscillations in both the average runoff rate and sediment yield. Furthermore, as the slope steepens, the amplitude of these oscillations increases. The process of slope erosion involves three stages: raindrop splash erosion, runoff erosion, and collapse damage. The sequence of slope damage locations is as follows: footslope, mid-slope, and hilltop. For the backfilled slope of completely weathered granite, the artificial slope can be controlled to around 20 degrees. Erosion on the slope mainly occurs after the formation of gullies, and slope management should focus on preventing gully formation before it happens.