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Block-flexure toppling failure is frequently encountered in interbedded anti-inclined rock (IAR) slopes, and seriously threatens the construction of hydropower infrastructure. In this study, we first investigated the Lean Reservoir area's geological setting and the Linda landslide's characteristics. Then, uniform design and random design were used to design 110 training datasets and 31 testing datasets, respectively. Afterwards, the toppling response was obtained by using the discrete element code. Finally, support vector regression was used to obtain the influence weights of 21 impact factors. The results show that the influence weight of the slope angle and rock formation dip angle on the toppling deformation among tertiary impact factors is 25.96% and 17.28%, respectively, which are much greater than the other 19 impact factors within the research range. For the primary impact factors, the influence weight is sorted from large to small as slope geometry parameters, joints parameters, and rock mechanics parameters. Joints parameters, especially the geometric parameters, cannot be ignored when evaluating the stability of IAR slopes. Through numerical simulation, it was qualitatively determined that failure surfaces of slopes were controlled by cross joints and that the rocks in the slope toe play a role in preventing slope deformation. [ABSTRACT FROM AUTHOR]

Rainfall with heavy intensity and long duration is a main inducing factor that triggers landslides on anti-inclined rock slopes. Numerous interbedded anti-inclined rock (IAR) slopes in Southwest China frequently experience mountain collapses and landslides under heavy rainfall. Therefore, it is necessary to study the failure mode of IAR slopes during rainfall. In this study, the Linda landslide and Mari landslide, typical IAR landslides in the study area, were used as examples to build a physical model of IAR slopes under continuous rainfall conditions, and a self-made rainfall simulation system was used to mimic natural rainfall conditions. The multi-physics data of displacement, velocity, stress, strain, pore water pressure, and acoustic signals in model deformation and failure under rainfall conditions were obtained using multi-field monitoring technology. In addition, the materials' water content and mechanical parameters at different locations of the model were obtained after the experiment. The analysis results indicate that: in the first and middle periods of rainfall, the slope model experienced a shallow local deformation and a holistic toppling deformation; until the late rain, the failure of the IAR slope caused by rainfall finally presented a typical failure mode of multiple failures and collapses of regressive landslides. According to its multi-field evolution characteristics, the velocity and acoustic signals were highly consistent with the failure characteristics of the model, which could be used as landslide early warning indicators. In addition, it was observed that the shape of the multi-slip surfaces generated by the model was a concave double straight line extending from the slope toe to the slope surface and sharing the failure section at the slope toe. Finally, the deformation and failure process of the model could be speculated to be divided into five stages based on the deformation behavior and multi-field physical data feature: the initial interlayer dislocation stage, the deformation stage, the crack propagation stage, the retrogressive failure stage, and the holistic failure stage. The failure mode and deformation mechanism of IAR slopes under rainfall were revealed in the model test, which could provide appropriate guidance for the analysis and evaluation of similar landslides. Highlights: The failure of the interbedded anti-inclined rock slope model caused by rainfall presented a typical failure mode of multiple failures and collapses of regressive landslides. The velocity and acoustic signals are highly consistent with the failure characteristics of the model, and the shape of the multi-slip surfaces was a concave double straight line extending from the slope toe to the slope surface. According to its multi-field evolution characteristics, the deformation and failure process of the model under rainfall conditions can be divided into five stages. [ABSTRACT FROM AUTHOR]

Block-flexure toppling failures in interbedded anti-inclined rock (IAR) slopes present significant risks to infrastructure and safety. Based on the Linda landslide field investigations, this study conducted a series of physical modelling tests encompassing 15 slope angle and bedding angle combinations. The aim of 15 sets of tests was to explore the deformation and failure mechanisms in IAR slopes. The observations during the deformation and failure stages elucidated how changes in slope and bedding angles influence rock mass deformation and failure characteristics. The findings highlight that slope angle critically impacts IAR slope stability, while bedding angle notably affects deformation depth, failure area, and failure surface configuration. IAR slopes with bedding angles less than 60° tend to exhibit shallow, single-surface failures with the linear failure surface, whereas bedding angles exceeding 70° lead to deep-seated, large-area, multi-surface failures characterised by double-folded failure surfaces. The magnitude of the failure inclination angle increases with slope and bedding angles, ranging from 0 to 35°. Furthermore, deformation and failure in IAR slopes involve the progressive extension of cracks from the slope crest to the interior, eventually reaching the slope toe. Finally, the block-flexure toppling process in IAR slopes can be divided into an incubation deformation stage and an accelerated deformation stage, and based on curve characteristics, different deformation modes of the IAR slopes can be further classified as stepwise cumulative accelerated deformation mode and leap deformation mode. Highlights: Fifteen cases of physical modelling tests covering various slope angles and bedding angles were conducted to replicate the deformation and failure mechanism in interbedded anti-inclined rock (IAR) slopes; Slope angle plays a pivotal role in determining the stability of IAR slopes, whereas bedding angle controls slope deformation depth, failure area, and failure surface characteristics; The IAR landslide is a progressive failure process that extends from the slope crest to the slope toe; The deformation process of IAR slopes can be categorised into the incubation deformation stage and the accelerated deformation stage. Additionally, the deformation mode can be further classified as either stepwise cumulative accelerated or leap deformation modes. [ABSTRACT FROM AUTHOR]

This study investigated a dynamic stability analytical model for bedding rock slope with soil interlayer, considering various rain patterns. The critical rain intensities for anhydrous and water-filled fissure were derived, respectively. Rain coefficients (i.e., concentration and peak position coefficients) were subsequently introduced to investigate rain patterns. The evolving water head under different infiltration scenarios was derived based on Darcy's law and mass conversation law. Additionally, the time-varying water pressure along soil interlayer was obtained based on triangular distribution assumption. An analytical model incorporating time-varying water head was established to predict slope stability based on limit equilibrium method. Numerical simulations further validated the analytical solutions for time-varying water head and pressure. The evolving characteristic of slope stability was analyzed, and a failure threshold was proposed. Results demonstrated that rain patterns and rain coefficients significantly impact on the rainfall threshold corresponding to slope failure. For uniform rain-induced slope failure, rainfall threshold tends to increase as rain intensity decreases. For unimodal rain-induced slope failure, the rainfall threshold is the largest for post-peak rain corresponding to slope failure, followed by the medium-peak rain, and the smallest for forward-peak rain. These results and findings enhance our understanding of the dynamic stability of bedding rock slope with inclined soil interlayer and provide valuable insights into assessing the evolving slope stability under different rain patterns. Highlights: An analytical model of dynamic slope stability coupling time-varying water head was established. Impacts of rain pattern and rainfall intensity on slope stability were systematically investigated. Rainfall threshold for slope failure considering different rain patterns was proposed based on analytical model. 〹 [ABSTRACT FROM AUTHOR]

Rock slope monitoring is an important aspect of better understanding the deformation behaviours and failure mechanisms of rock slopes. In this study, a multi-smartphone photogrammetric monitoring (MSM) system for rock slope hazards was proposed and developed. The system, which has nine smartphones embedded in device units, is based on structure from motion and multi-view stereo (SfM-MVS) photogrammetry. All smartphones were controlled remotely only through smartphone applications and the 4G internet. The accuracy of the system under various shooting strategies and light conditions is comprehensively evaluated in terms of both trueness and precision for two rock slopes. The distance errors of target points and the cloud-to-cloud distance were applied to assess the trueness and precision of the reconstructed slope models through the system. The results show that easy-assembly and low-cost systems have centimetre-level accuracy in the evaluation tests. The shooting strategy with a larger overlap rate tends to improve the trueness of the system, and insufficient light conditions increase the distance errors of the system. In addition, a rock slope change detection with 0.006–1.123 m3 was monitored through the MSM system. Owing to these characteristics, the MSM system has the potential to become a helpful method for rock slope reconstruction and monitoring. [ABSTRACT FROM AUTHOR]