Abstract: To truly reflect the instability process and failure mechanism of slopes within fractured zones, this paper presents the evaluation results of slopes in Gangtou Tunnel. The main water conveyance structure in the middle route of the South-to-North Water Transfer Project was studied in the paper to study the stability of the three-dimensional effect of slopes. Due to the complexity of the slope in the study area with an alternate deposition of soft and hard rock strata, the fractured zones are introduced in the 3D numerical model to simulate the actual dispositions of bedrock and overburden soil. Based on the strength reduction method, the influence of the fractured zones on the slope stability was studied. The failure mechanism of the fracture zones, as well as the sensitivity of the cohesion and internal friction angle of the bedrock and soil mass of the slope to its stability were analyzed. The results show that the strength properties at the fractured zones are significantly reduced, which leads to large displacements at the upper layers of the project site, which greatly reduces the factor of safety of the target slope. If the other conditions remain unchanged, the cohesion and the internal friction angle of the soil have an approximately linear relationship with the factor of safety of the target slope. Therefore, combined with the principles of the sensitivity analysis, the sensitivity to effectively identify the internal friction angle and cohesive force is high, which can improve the efficiency of slope reliability analysis.

Key words: Slope Stability Analysis, Fractured Zone, Three-Dimensional Simulations, Factor of Safety, Sensitivity Analysis