## 5 Conclusions  
Through conducting uniaxial compression tests, combined with acoustic emission monitoring, a comparative analysis was made on the yield strength, elastic modulus, acoustic emission characteristic signals, failure characteristics, and energy evolution laws of five different coal-rock ratio samples. The main conclusions are as follows:  
1. The damage and failure behavior of the six types of samples under uniaxial compression conditions are basically consistent, all experiencing the stages of compaction, elasticity, yield, and post-peak failure. The failure of the composite samples mainly occurred in the coal body part, with the strength of the sample being influenced by  
Figure 11: Schematic diagram of force on the combination.  
coal body defect structures and sizes. With the increase in the coal-rock ratio, the peak strength and elastic modulus of the samples show a gradually decreasing trend. In the transition zone of the primary coal-rock composite, different interface effects will occur on the coal-rock body part. The derived stress of the coal body is horizontal tensile stress, which promotes the deformation of the rock and coal at the interface. The derived stress of the rock at the interface is horizontal compressive stress, which restricts the deformation of the rock and coal at the interface. The closer the coal sample is to the interface, the stronger the restrictive effect of the interface effect. 3. The coal-rock combination interface has more developed cracks, leading to more initiation points at the interface. When cracks in the rock part begin to propagate, the failure of the coal body induces the failure of the rock. After the rock fails, a large amount of energy is released and transferred to the coal body, exacerbating the degree of damage and the dynamic manifestation strength of the coal body, forming a feedback mechanism of mutual damage between the coal body and the rock body. 4. The acoustic emission signals of single-rock samples exhibit low AF and high RA characteristics, indicating shear failure. In contrast, the acoustic emission signals of single-coal samples and composite samples exhibit significant high AF and low RA characteristics, with tensile failure being the main destabilizing factor. Moreover, with the increase in the coal proportion, the proportion of RA values gradually increases, while the proportion of AF values decreases, indicating a transition from tensile failure to tensile-shear composite failure in the samples.  
Y.C.: Conceptualization, Methodology, Writing--original draft. X.Z.: Methodology, Validation. L.W.: Validation. Q.F.: Resources, Supervision. Q.L.: Formal analysis. All authors have read and agreed to the published version of the manuscript.  
This work is supported by the National Key Research and Development Program of China (No. 2023 YFC3009002), the Open Research Grant of Joint National-Local Engineering Research Centre for Safe and Precise Coal Mining (Anhui university of Science and Technology) (Grant No. EC2022021), and the National Natural Science Foundation of China (No. 52204220).  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.