## 3 Results and Analysis
### Acoustic Emission Analysis
It was shown that the maximum value of the acoustic emission ringing counts was negatively correlated with the gypsum content in specimens. As depicted in Figure 9, the cumulative acoustic emission count changes roughly experienced four stages. In the first stage, the numerical growth of the cumulative acoustic emission count curve was slow, with no or minimal occurrence of acoustic emission events during this stage. During the second stage, the cumulative count of acoustic emission ringing gradually increased. During this time, the curve demonstrated a gentle slope with sporadic occurrences of several acoustic emission events. This stage corresponded to the elastic deformation stage of the stress-strain curve of the specimen. Due to the continuous action of the load, new cracks appeared inside the specimen, and acoustic emission events were detected at this stage. The cumulative count of acoustic emission in the third stage exhibited a state of rapid growth, with a significantly steeper slope compared to that observed in the second stage. This stage had a good corresponding relationship with the damage stage of the stress-strain curve of the specimen. At this stage, the pores and cracks inside the specimen were connected and interconnected, resulting in more acoustic emission events than in the second stage, and the curve rose faster. In the fourth stage, there was a sudden and significant increase in the cumulative ringing count of acoustic emissions, resulting in a curve that surged almost vertically. This stage signified the failure of the specimen, with the highest ringing count being generated during this phase. The four stages of cumulative acoustic emission ringing count exhibited a strong correspondence with the initial compaction stage, elastic stage, damage stage, and post-failure stage during typical rock uniaxial compression failure. To better explain the acoustic emission ringing count characteristics of rock-like specimens in different deformation stages, the following Formula (1) gives the calculation formula of the cumulative ringing count change of acoustic emission. \[\omega=\frac{N_{A}}{N} \tag{1}\]  
\(N_{A}\) is the value of the cumulative ringing count of the acoustic emission up to a certain moment, and \(N\) is the value of the cumulative ringing count of the acoustic emission after the compression failure of rock-like specimens. According to the above Formula (1), the change of the cumulative ringing count of the acoustic emission in different stages of each specimen was calculated, as shown in Table 3.  
An analysis of Table 3 shows that the large value of the acoustic emission ringing count was mostly concentrated in the fourth stage of the change of the acoustic emission cumulative ringing count curve, which contained abundant acoustic emission signals. An analysis of A1-A4 shows that when the cumulative ringing count of the acoustic emission of rock-like specimens without gypsum changed by more than 50%, the specimens entered the failure stage. Due to the hard and brittle characteristics of the specimen, the specimen was destroyed rapidly, and the acoustic emission events were less. The analysis of B1-B4 shows that the cumulative ringing count of the acoustic emission of rock-like specimens containing gypsum changed by more than 28%, and the specimens entered the failure stage. Gypsum increased the toughness of rock-like materials, the damage of specimens was slow, and the acoustic emission signal was more than that of specimens A1-A4. Through the analysis of C1-C4, it was found that with the increase in cement content in rock-like specimens, the change value of the acoustic emission cumulative ringing count of rock-like specimens gradually increased, indicating that cement increased the brittleness of the material and accelerated the failure of the rock-like materials.