## 6 Conclusions  
This paper investigated the mechanical characteristics of soil-rock mixture under uniaxial compression conditions, from both macro- and meso-mechanical perspectives. The mechanical properties of soil-rock mixtures with varying rock contents and soil-rock interface strength were discussed based on experimental and simulation results, and the mechanisms of the two key influence factors on mechanical characteristics were explored in detail. The findings provide valuable insights for understanding the mechanical properties of soil-rock mixture in the Yunnan region and for mitigating geological hazards on deposit slopes. The main conclusions are as follows:  
1. At the macro-scale, the axial stress-strain curves of soil-rock mixture specimens with varying rock contents exhibited similar behaviors under uniaxial compression conditions. The axial stress presented a distinct stress drop, with specimen failure occurring primarily during the peak strength and stress drop stages, characterized by surface soil detachment and penetration failure. As the rock content increased, the failure characteristics of the soil-rock mixture specimen changed from a dominant crack that penetrated through the material to a more complex multiple shear fractures, as rock blocks gradually played a critical role in the localized destructions. 2. At the meso-scale, a generation method for irregular rock block models based on the morphology of real rock blocks was proposed. The rock content and the meso-parameters of the contact model between the soil and rock block particles were analyzed to identify the key factors influencing the mechanical characteristics of soil-rock mixture. For the rock content, the distribution of internal force chains became more uneven, with greater concentration in the soil-rock contact areas as the rock content increased. This made these regions more susceptible to contact-induced fractures. For the soil-rock interface strength, the likelihood of contact failure between soil and rock particles significantly increased as the friction coefficient of the interface decreased, making the rock blocks more prone to rolling and displacement within the soil matrix. 3. Experimental and simulation results show that the UCS value and the associated axial strain of soil-rock mixture decreased exponentially as the rock content increased. Furthermore, as the friction coefficient of the interface decreases, the disturbance effect of rock content on UCS became more pronounced. An estimation formula for UCS of soil-rock mixture, influenced by rock content and the soil-rock interface strength, was developed. Analysis of the interrelationships between the macroscopic roughness of rock block particles, the strength characteristics of the soil matrix, and the microscopic contact surface friction coefficient clarified the physical significance of the parameters used in the estimation formula. Conceptualization, Z.Z. and Q.S. ; data curation, X.F. ; methodology, X.F., S.W. and Y.F. ; resources, Z.Z. and X.F. ; validation, Q.S. and S.W. ; writing--original draft, Z.Z. and Y.F. ; corrections, modifications, and final acceptance, all authors. All authors have read and agreed to the published version of the manuscript. This paper was funded by the Open Research Fund of the State Key Laboratory of Geohaz- and Prevention and Geo-environment Protection (Grant No. SKLGP2022K010), the Key R&D Program of Yunnan Province (202303 AA080010), Natural Science Foundation joint funding of Liaoning (Grant No. 2023-BSBA-261), Basic Research Program of Liaoning Provincial Department of Education (Grant No. LJ212410142010), the Youth Innovation Promotion Association CAS (Grant No. 2021325), National Natural Science Foundation of China (Grant No. 52409137, 52179117). Data Availability Statement: The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author. Acknowledgments: Thank you to all the authors who have contributed to the research in this field.