## 6 Conclusions  
Granite terrains generally provide favorable geological conditions for dam construction. However, the presence of intrusive granite fracture zones introduces significant geotechnical complexities that require careful evaluation during gravity dam design. This study investigates the critical role of dominant structural planes in granite intrusion zones and their impact on gravity dam stability under coupled seepage-stress conditions. The key findings are presented as follows:  
1. Comprehensive analysis of structural plane spatial distribution identified faults f7, f9, and f11, joint set f1, and the intrusive fracture zone as the dominant structural planes governing dam foundation stability. Integration of three-dimensional structural mapping with rigid body limit equilibrium analysis demonstrated that: (i) deep sliding mechanisms can be conclusively excluded, and (ii) the critical failure mode consists of shallow sliding along the fracture zone associated with Late Yanshanian volcanic magma intrusion.
2. Finite element numerical simulations were conducted to investigate the stress-strain characteristics of the shallow sliding mechanism. The three-dimensional analysis revealed: (i) Distinct stress concentration at the dam-fracture zone interface; (ii) Under seepage-stress coupling conditions, streamwise displacement increased by 143% compared to uncoupled analysis, while vertical displacement reduced to 83% of the  
Figure 17: Plastic zone under different reduction coefficients in dam section 4 ((a). F = 1.00; (b). F = 2.00; (c). F = 2.84).  
baseline value; (iii) The shallow sliding failure pattern is governed by the interaction between the fracture zone and structural planes. These results demonstrate that seepage-induced streamwise displacement represents a critical stability concern for gravity dams. Consequently, seepage-stress coupling analysis must be incorporated in anti-sliding stability assessments to ensure reliable safety evaluations.
3. The anti-sliding stability of the gravity dam foundation was systematically evaluated using the strength reduction method. The numerical simulations revealed a progressive failure mechanism characterized by (i) Initial development of plastic zones within the fracture zone and major fault locations; (ii) Subsequent propagation of plasticity both upstream and downstream along the structural discontinuities. The analysis demonstrates that these failure patterns pose significant stability risks, necessitating targeted reinforcement measures in the fracture zone and fault regions to ensure adequate safety margins.  
Compared with existing research results on the anti-sliding stability analysis of gravity dams, this study incorporates seepage field simulation results, couples the seepage field, and considers the influence of seepage on the dam foundation's anti-sliding stability, making the analysis more consistent with real-world conditions. The results obtained from practical engineering applications provide valuable guidance for engineering projects.  
Methodology, M.D. and Y.H.; Software, X.L., H.Z. and X.Z.; Investigation, X.L., Y.H. and X.Z.; Resources, M.D. and Y.H.; Data curation, H.Z.; Writing--original draft, M.D. and X.L.; Writing--review & editing, H.Z. and X.Z.; Visualization, X.L., H.Z. and X.Z.; Supervision, M.D.; Project administration, Y.H. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author. The raw data supporting the conclusions of this article will be made available by the authors on request.  
Author [PERSON] was employed by the company PowerChina Beijing Engineering Corporation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.