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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]

Flexural toppling is one of the main failure modes of natural and manmade anti-dip layered rock slopes. Based on cantilever slab tensile theory, the failure mechanism of flexural toppling was analyzed. A toppling slope is divided into three parts: the stability, tensile and shear zones. By considering this failure mechanism, a new stability analysis method for slopes against flexural toppling failure is proposed using equilibrium theory. In addition, a sensitivity analysis is performed to investigate the locations of possible failure surfaces and zones as well as changes in the stability of anti-dip rock slopes under different conditions. The results show that the positions of the inter-column forces have almost no effect on the stability factor but affect the areas of the tensile zone and the shear zone. The angle of the most dangerous potential failure surface increases with increasing dip angle and slope height, whereas the stability factor is negatively correlated with the dip angle and slope height but is positively correlated with the layer thickness. The failure mode is essentially flexural toppling when the layer thickness is small, but the failure mode gradually transitions to shear-sliding with increasing layer thickness. Finally, a real case study is analyzed using this method, and the calculated results are consistent with the actual conditions. [ABSTRACT FROM AUTHOR]