## 1 Introduction
The authors also proposed stress thresholds for crack development, closure, initiation, and damage. Using digital image correlation technology, [PERSON] et al. [18] examined the mechanical properties and damage modes of coal rocks with varying laminations following water immersion. They observed that water-immersed coal rocks underwent a transformation from uniform deformation to non-uniform deformation during the damage process. Coal rock damage is closely tied to energy fluctuations. The process of fracture aids in reflecting the overall impact of water damage on the coal rock. The accumulation and release of strain energy contribute to the generation and expansion of internal cracks in coal rocks. During the rupture process, the existence of acoustic emission phenomena is attributed to the generation of microcracks. Scholars have investigated the mechanism of rupture evolution in rocks by using acoustic emission. [PERSON] et al. [19] employed a rock straight shear test coupled with an acoustic emission detection system to determine the mechanical properties and strength damage law of sandy mudstone under water. [PERSON] et al. [20] investigated the mechanical properties and acoustic emission characteristics of water-saturated amphibolite under varying immersion durations. They developed an acoustic emission damage model for water-saturated rocks based on the immersion duration and observed that the change in the cumulative acoustic emission count aligned with the internal damage evolution of the rock samples. [PERSON] et al. [21] conducted a uniaxial compression test to investigate the deformation laws and acoustic emission characteristics of coals with varying strengths. Their study investigated the deformation processes and acoustic emission characteristics of both soft and hard coals and revealed that hard coals possessed distinct mechanical properties compared to soft coals, and the deformation processes of both types were divided into two stages. This provides a valuable reference for the application of acoustic emission technology in coals with different strengths. [PERSON] et al. [22] conducted uniaxial compression experiments to analyze the mechanical properties of coal rocks under the joint effects of high temperatures and water immersion. They also examined the acoustic emission patterns during the damage process and obtained the generation and alteration mechanisms of the acoustic emission signals in coal rocks subjected to high temperatures and water immersion. [PERSON] et al. [23] carried out uniaxial compression tests on coal rock assemblages with different water immersion conditions and investigated their acoustic emission evolution. [PERSON] et al. [24] conducted uniaxial cyclic loading tests and utilized an acoustic emission system to investigate the mechanical properties of igneous rocks with varying water content. They observed that saturated, water-immersed igneous rocks exhibited lower peak strength, higher strain, and a greater number of cumulative acoustic emissions. Their study serves as a useful reference in studying the mechanical properties of coal rock in submerged water conditions. The issue of mine water treatment and utilization is of great significance in China. In 2013, the National Development and Reform Commission (NDRC) issued the Development Plan for Mine Water Utilization [25]; in 2014, the State Council issued the Action Plan for the Prevention and Control of Water Pollution, which explicitly pointed out the need to \"promote the comprehensive utilization of mine water, and give priority to the use of mine water for the supplemental water of the coal mining area, and for the production and ecological water of the neighboring regions\" [26]. This work examines the mechanical properties and rupture evolution characteristics of the coal rock body via uniaxial compression testing with varying water immersion durations and obtains a strength deterioration model for coal rock with different immersion durations.