Mechanisms of rainfall-induced landslides in gently inclined red beds in the eastern Sichuan Basin, SW China

Abstract

Red beds are widespread in the eastern Sichuan Basin, SW China, and are often called Blandslide prone strata^. The dip angle of these red beds is commonly less than 10°, which is much less than the angle of internal friction between the bedding planes. Thus, in theory, failure will not occur along the bedding planes in such strata. We used field methods, numerical modeling, and ring shear tests to investigate the effects of rainfall on landslides in shallow-dipping red beds, using the Qingning landslide in SW China as an example. Our results suggest that the probable mechanisms leading to failure are (1) permeation of rainfall through the cracks at the back of the landslide site that increases the hydrostatic water pressure, which adds to the sliding stress and reduces the effective stress on the failure surface, gradually destabilizing the mass. In the Qingning landslide, the maximum water pressure was as high as 21.8 m before failure. When the factor of safety decreased markedly to 1.015, the sliding mass started to slowly slide.(2) As sliding takes place, the sliding zone soil is under undrained shear and its shear strength decreases sharply to a critical value, which promotes rapid sliding. In the Qingning landslide, the shear resistance of the sliding zone soil decreased markedly to 25.9 kPa as the pore water pressure increased to 118.3 kPa. This study may provide a theoretical basis for landslide forecasting in gently inclined red beds of the eastern Sichuan Basin as well as in similar geological settings worldwide.

The Monitoring-Based Analysis on Deformation-Controlling Factors and Slope Stability of Reservoir Landslide: Hongyanzi Landslide in the Southwest of China

“…The majority of the deformations occurred during the declination of the reservoir water level, and no large deformations were observed when the reservoir water level remains stable or increases. Similar observations were also made by previous studies [12][13][14][15][16][17][18]. Due to the extensive deformation of the Hongyanzi landslide, a multiparameter monitoring program was conducted on the Hongyanzi landslide to advance the understanding on the deformation characters and its major influencing factors.…”

Characterization of Microscopic Pore Structures of Rock Salt through Mercury Injection and Nitrogen Absorption Tests

“…3. According to previous studies [24,25], the pore size of rock salt can be classified into three categories as follows: macroscopic pore with size larger than 8 m, microscopic pore with a size varying between 1 m and 8 m, and subpore with pore size that is smaller than 1.0 m. Among these three types of pore, macroscopic pore is generally flat-shaped, the microscopic pores form often network, and subpore is connected as pore throat, as displayed in Figure 1.…”

Spatiotemporal distribution and failure mechanism analyses of reservoir landslides in the Dagangshan reservoir, south-west China

“…These reservoir landslides pose a great threat to the safety of hydropower stations (especially high dams), coastal infrastructure and human life. In addition, they may engender a chain of subsequent serious disasters, including landslide surges, blocked rivers and the formation of dammed lakes (Xu et al 2015;Zhang et al 2015;Gomez et al 2016;Huang and Wang 2017). Therefore, reservoir landslides have been widely investigated in recent years, and related studies on their spatiotemporal distribution characteristics and the triggering mechanisms of landslides can help us to formulate hazard prevention and mitigation measures (Yin et al 2015;Zhou et al 2016a;Iqbal et al 2017).…”