Failure evaluation and control factor analysis of slope block instability along traffic corridor in Southeastern Tibet

The instability of slope blocks occurred frequently along traffic corridor in Southeastern Tibet (TCST), which was primarily controlled by the rock mass structures. A rapid method evaluating the control effects of rock mass structures was proposed through field statistics of the slopes and rock mass structures along TCST, which combined the stereographic projection method, modified M-JCS model, and limit equilibrium theory. The instabilities of slope blocks along TCST were then evaluated rapidly, and the different control factors of instability were analyzed. Results showed that the probabilities of toppling (5.31%), planar (16.15%), and wedge (35.37%) failure of slope blocks along TCST increased sequentially. These instability modes were respectively controlled by the anti-dip joint, the joint parallel to slope surface with a dip angle smaller than the slope angle (single-joint), and two groups of joints inclined out of the slope (double-joints). Regarding the control effects on slope block instability, the stabilization ability of double-joints (72.7%), anti-dip joint (67.4%), and single-joint (57.6%) decreased sequentially, resulting in different probabilities of slope block instability. Additionally, nearby regional faults significantly influenced the joints, leading to spatial heterogeneity and segmental clustering in the stabilization ability provided by joints to the slope blocks. Consequently, the stability of slope blocks gradually weakened as they approached the fault zones. This paper can provide guidance and assistance for investigating the development characteristics of rock mass structures and the stability of slope blocks.