## 6 Conclusions  
In this study, the weakening mechanisms of the roof sandstone in the Renlou Coal Mine under water-rich conditions and the corresponding roadway's surrounding rock control measures were systematically investigated. By combining multi-path true triaxial tests, microstructural analysis, and industrial trials, the significant impact of water-rock interactions on the deformation and failure characteristics of water-saturated sandstone was revealed, and effective support strategies were proposed. The main conclusions are as follows. 1. The results of the microstructural analysis indicated that under water-rich conditions, the expansion and degradation of clay minerals led to a significant weakening of the sandstone structure. XRD and SEM analyses revealed that the main mineral components of the sandstone included quartz, feldspar, and clay minerals such as kaolinite and illite. The expansion and degradation of these minerals are key factors contributing to the reduction in rock strength. 2. The true triaxial experiments revealed the failure modes of water-saturated sandstone under complex stress conditions. As the water content increased, the failure mode of the sandstone gradually shifted from brittle to ductile, and crack propagation became more intense, leading to the formation of numerous associated cracks and complex crack networks. This significantly reduced the stiffness and strength of the rock. The increase in the water content caused a marked decrease in the initiation, closure, and damage stresses of the sandstone, accelerating the initiation and development of cracks. As the moisture content ranged from 0 to 100%, the damage stresses of the samples under the four paths decreased by 26.81%, 7.27%, 6.67% and 21.94%, respectively. Water infiltration weakened the load-bearing capacity of the rock, making the surrounding rock more prone to failure under lower-stress conditions, which, in turn, led to a significant decline in the roadway's stability. 3. The AE monitoring results demonstrated the significant evolution of cracks in the surrounding rock under water-rich conditions. The variations in the AE count and \(b\)-value revealed the entire process of crack initiation, propagation, and coalescence. Under a high water content, the AE activity increased, and the \(b\)-value decreased significantly, indicating more intense crack propagation and an increased risk of instability and failure. This behavior is consistent with the observed macroscopic failure patterns. 4. The industrial trials validated the effectiveness of the proposed support and grouting modification measures. The stability of the surrounding rock of the roadway was significantly enhanced by integrating closure of the surrounding rock and groutingmodification techniques. The displacements of the roof, floor, and sidewalls were substantially reduced, and the roof delamination was effectively controlled. The supporting loads of bolts and anchor cables decreased by an average of 22.5% and 31.07%, respectively, and the overall bearing capacity of the support system was significantly improved, ensuring the safety and service life of the roadway. The conclusions of this study have significant engineering implications for the stability control of coal mine roadways under water-rich conditions. They also provide scientific guidance for the design and construction of support systems in coal mines with similar geological conditions. Z.Z. : writing--original draft, formal analysis, data curation, conceptualization. Y.F. : methodology, funding acquisition, conceptualization. Q.X. : visualization, data curation, funding acquisition. K.L. : methodology, conceptualization. M.H. : visualization, conceptualization. L.F.: data curation, conceptualization. All authors have read and agreed to the published version of the manuscript. This research was funded by Yunlong Lake Laboratory of Deep Underground Science and Engineering Project (no. 104024003), the Natural Science Foundation of Jiangsu Province (grant no. BK20220024, BK20241649). Not applicable.