## 1 Introduction  
Mining cavern excavation and support, large-scale rock slope excavation and support, and the repeated passage of vehicles through bridges and tunnels are all rock engineering activities that are subjected to cyclic and repetitive loads [1; 2; 3]. This type of cyclic loading can lead to fatigue damage and even fracture in structures, and unlike uniaxial compressive loads, it has a more severe impact on material deformation and failure. Therefore, it is necessary to conduct an in-depth analysis of the deformation and failure response processes of rocks under cyclic loading and unloading [4; 5]. Currently, many scholars primarily use indoor experiments to study the mechanical properties of rocks under cyclic loading and unloading. [PERSON], [PERSON] et al. [6] conducted cyclic loading and unloading three-point bending tests on granite notched beams to analyze the fracture characteristics of granite. The study found that the fracture toughness of granite under cyclic loading and unloading is lower than that under static loading. [PERSON], [PERSON] et al. [7] performed uniaxial cyclic loading and unloading tests on brittle rocks, and the results showed that the Poisson's ratio of brittle rocks gradually increases, while the elastic modulus increases after the first cycle and then slowly decreases. Once the crack propagation stage is reached, the degree of damage increases rapidly. [PERSON], [PERSON] et al. [8] found that the axial deformation of sandstone under uniaxial cyclic loading and unloading presents three stages: initially, the strain is very small but grows rapidly; in the stable stage, the strain grows gradually; and in the failure stage, the strain increases rapidly. The hysteresis loop density of these three stages shows a sparse-dense-sparse pattern, and the shape of individual hysteresis loops follows a fat-thin-fat development trend. [PERSON], [PERSON] et al. [9], [PERSON] et al. [10,11], and [PERSON] [12], based on the LURR (Load-Unload-Reloading) theory, studied the mechanical properties and mechanism evolution of sandstone under different loading and unloading conditions (MCT, FCT), suggesting that under the FCT stress path, the macroscopic structure of the specimen is dominated by large particles and the friction dislocation phenomena between particles are weakened. Currently, for cyclic loading and unloading tests, most scholars use acoustic emission (AE) and digital image correlation (DIC) technologies to monitor the entire change process of rocks under loading. [PERSON] et al. [13] and [PERSON] et al. [14] studied the Kaiser and Felicity effects of AE activity and discussed the impact of a significant increase in AE events on these effects. The research found that when the Felicity ratio is less than 1, AE activity is intense and the rock is in an unstable state, which is known as the Felicity effect. Conversely, when the Felicity ratio is greater than 1, the rock is in a stable state, and this phenomenon is called the Kaiser effect. This point can be used as a precursor for predicting rock failure. [PERSON] et al. [15] found that under cyclic loading and unloading, the AE characteristics of rock fracture show a clear Kaiser effect, and the Felicity effect is significantly observed when the loading force reaches 70% of the peak value. The b-value is commonly used, based on AE, to predict the precursors of rock failure, and a significant increase or decrease in the b-value suggests that the rock may have a large number of cracks or is about to become unstable and fail [16; 17; 18]. Under low stress conditions, b-value activity is weak and almost imperceptible, while under high stress states, b-value activity is intense. The b-value method is more effective than the Felicity effect in predicting rock failure [19; 20]. AE is used to classify and calculate the proportion of crack types. [PERSON], [PERSON] et al. [21] combined real-time AE monitoring and computed tomography (CT) to study the anisotropic crack propagation and classification of crack types in laminated marble.