Yanni Zheng

The Alagou Reservoir was officially closed for water storage in November 2014. Since September 2016, gradual slope collapse and deformation have been observed at elevations ranging from 600 to 1050 m upstream of the left bank of the Alagou Reservoir dam site. The increasing annual deformation raises significant concerns about a potential landslide, which could lead to surge waves, posing a threat to both the dam and the surrounding environment. Owing to difficult access and worsening conditions, thorough exploration of the site was challenging. Consequently, after emptying the reservoir, we conducted on-site investigations using satellite D-InSAR analysis, numerical modelling and post-event monitoring. This multidisciplinary approach aimed to investigate the relationship between deformation behaviour, triggering conditions and reservoir water-level changes. Our study provides valuable insights into the complex geological processes involved in slope deformation and failure mechanisms induced by water-level fluctuations. We elucidated the interplay between deformation behaviour and triggering conditions, which is essential for designing effective reinforcement treatments for deformed slopes. Although InSAR has proven to be a cost-effective tool for monitoring surface deformation, it offers limited insights alone. Therefore, we recommend a multi-technique approach incorporating geophysical, geotechnical and remote sensing data for a comprehensive understanding of slope stability.

A discrete-continuous coupling analysis method based on FLAC2D/PFC2D is established with the help of the program’s own FISH language and Socket O/I data transfer interface. According to the statistical characteristics of the mesostructure of the slope site, the computer stochastic simulation method is used to construct the mesostructure model of the soil–rock mixture in the discrete domain. The deformation and failure mechanism of the SRM slope is studied by using the established discrete-continuous coupled analysis method. The results show that the statistical distribution of the mesoscopic contact characteristics (such as contact direction and contact force) between soil and rock particles inside the slope changes and adjusts significantly. Among them, the main direction of the statistical distribution is adjusted most significantly, and the main direction is finally adjusted to being basically the same as the sliding direction of the slope. The change in the mesoscopic contact characteristics between soil and rock particles is the internal driving factor for the macroscopic deformation of the slope and the adjustment of the stress state.

This study assesses the efficiency of the empirically recommended supported design of the underground powerhouse of the Panlong pumped-storage power station in Chongqing, China by using 3D distinct element code (3DEC). Field and laboratory tests were conducted to investigate the geological properties of intact rock and rock mass. The results showed that the stability of the large powerhouse may be controlled by the soft rock (mudstone) layers. The rock mass was classified in terms of the Q classification system, basic quality (BQ) method, and hydropower classification (HC) method, and then the supported system was put forward. The efficiency of the designed supported was checked based on the numerical simulation results of deformation and plastic zone. The results showed that the installed support reduces the radius of the plastic zones and the maximum deformation significantly.