Slow-moving landslides, characterized by sustained destructive potential, are widely distributed in northwest China. However, research on the damage mechanisms of masonry buildings caused by slow-moving landslide-induced surface deformation is significantly lacking, which severely restricts the physical vulnerability assessment of masonry structures and the quantitative risk evaluation of slow-moving landslides. Through field investigations, CDEM numerical simulations, and statistical analyses, this study reveals the cooperative deformation characteristics and progressive failure mechanisms of masonry buildings subjected to ground cracks in slow-moving landslides, and establishes physical vulnerability curves for four distinct ground crack scenarios. The key findings indicate that masonry buildings affected by slow-moving landslides primarily exhibit transverse wall cracking and longitudinal wall inclination due to ground crack propagation. As crack propagation continues, the first-floor walls exhibit significantly higher Mises stresses compared to those on the second floor. Wall inclination rates demonstrate a distinct threshold effect during crack propagation: below the threshold, inclination increases linearly with crack displacement, while above the threshold, it exhibits exponential growth. Under identical crack displacement conditions, wall inclination rates decrease in the following order: horizontal tension, combined tension, settlement, and combined uplift scenarios. The differential effects of these scenarios on wall inclination become more pronounced with increasing crack displacement. Weibull functions were employed to fit vulnerability curves for masonry structures under four ground crack scenarios, revealing displacement thresholds of 22 cm, 26 cm, 27 cm, and 37 cm for complete structural vulnerability (V = 1) in each respective scenario. These findings provide valuable insights for vulnerability prediction and emergency rapid assessment of buildings subjected to slow-moving landslides across various disaster scenarios.

Slow-moving landslides are typically characterised by pre-existing shear zones composed of thick, clay-rich, and mechanically weak soil layers that exhibit heightened sensitivity to changes in moisture content and hydrological conditions. These zones, often governed by variations in suction and degree of saturation, play a critical role in the stability and long-term behaviour of slow-moving landslides. In this study, we investigate the influence of the degree of saturation on the mechanical properties of shear-zone soils from a reactivated slow-moving landslide in the Three Gorges Reservoir area, China. A series of laboratory experiments, including consolidation, reversal direct shear, and ring-shear tests, were conducted on reconstituted shear-zone soil samples at varying degrees of saturation. The test results indicate that increasing the degree of saturation has a marked impact on the compressibility of the soils, with saturated samples exhibiting greater compressibility and unsaturated samples demonstrating reduced compressibility. Both shear tests indicate that higher saturation leads to a reduction in peak and residual shear strength, likely due to elevated pore water pressures and a decrease in inter-particle bonding forces. These insights emphasise the need to account for varying degrees of saturation when analysing the mechanical behaviour of slow-moving landslides, contributing to an improved understanding of their deformation patterns and failure mechanisms.

This paper presents the analysis and results of a 14-year monitoring of slow-moving landslide behavior along a 100 m high slope at Serra do Mar, Brazil. The slope is located near a roadway and an industrial area and was suffering from creep movements triggered by an excavation at its foot. Movements were especially severe during the rainy periods due to water table fluctuation. Inclinometer readings from 2009 to 2011 showed that the sliding involved a soil mass of 15 to 20 m thick and was in the so-called tertiary phase, with relatively high acceleration. Prediction models showed that the slope failure would probably occur in another two to three years, which required immediate implementation of mitigation actions. By the end of 2011, several deep horizontal drains were installed along the slope to reduce the water table level. Since then, the inclinometers showed that acceleration was eliminated and velocity was substantially reduced, bringing the slope back to primary and secondary, stable movements. Monitoring results of deep horizontal drains shows that flow volumes increase substantially during the rainy seasons, showing that the solution efficiently stabilizes the slope. With monitoring results for both secondary and tertiary creep phases, and comparisons to other monitored slopes in the region, benchmark parameters related to slope velocity and acceleration for Serra do Mar slopes are discussed and presented. This constitutes the first organized study on slope movement velocities at Serra do Mar and presents an important contribution to researchers and designers.

Ancient landslides tend to reactivate along pre-existing slip zones that have reached a residual state. On the eastern margin of the Tibetan Plateau, previous research has indicated that the slip zone of ancient landslides is primarily composed of clayey soil with gravel, known as gravelly slip zone soil. However, the relationship between the macromechanical behavior of gravelly slip zones and the mesostructure of the shear surfaces affected by gravel is still unclear. Herein, ring shear tests and reversal direct shear tests were performed on gravelly slip zone soil, and the 3D morphology and shear surface roughness were quantitatively characterized by using 3D laser scanning technology and the power spectral density method. The results showed a significant correlation between the friction coefficient of the shear surface and its roughness. Gravel played a crucial role in influencing the macromechanical behavior of slip zones by altering the mesomorphology of the shear surfaces. By analyzing the mechanical properties of the contact unit on the shear surface, the residual strength of the gravelly slip zone was found to be jointly controlled by the basic strength of the fine-grained soil and the undulations caused by the gravel. Finally, a residual strength model was developed for the gravelly slip zone considering both the strength of the fine-grained soil and the shear surface roughness caused by the gravel. The reactivation of ancient landslides has caused serious casualties and economic losses. Field investigations have revealed that the slip zones of ancient landslides commonly contain gravel. However, we still have limited knowledge regarding the effects of gravel on the behavior of slip zones. We carried out shear tests on gravelly slip zone soils and quantitatively characterized the shear surface morphology. Our results showed a strong correlation between the friction coefficient of the shear surface and its roughness. We found that the presence of gravel significantly influenced the macromechanical behavior of the slip zone by altering the mesostructure of the shear surface. Based on our findings, we developed a residual strength model for the gravelly slip zone that considers both the strength of the fine-grained soil and the roughness of the shear surface caused by the gravel. Our study provides valuable insights into the behavior of ancient landslides along pre-existing slip zones and improves our understanding of the role of gravel in influencing their macromechanical behavior. The friction coefficient of the slip zone is positively correlated with the shear surface roughness The gravel controls the macromechanical behavior of the slip zone by altering the morphology of the shear surface A residual strength model for the gravelly slip zone soil considering the shear surface roughness caused by gravel is proposed