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The existing research data show that, after reservoir impoundment, due to the repeated rise and fall of water level and water-rock interaction, the mechanical parameters of landslide are reduced, which will have an adverse effect on the stability of landslide. Therefore, sufficient attention must be paid to the stability of slope after reservoir impoundment. Hejia landslide is the largest landslide near the bank of Miaojiaba hydropower station, and its stability plays an important role in the normal operation of the hydropower station. Through field investigation and analysis of regional geological conditions, it is concluded that Hejia landslide is a large-scale landslide, through long-term sliding-bending deformation; it is generated from the external hard rock with thick layers and sliding zone for layered soft rock; the formation mechanism of landslide is as follows: (1) high-steep and hard-soft layered slope is the slope structure condition that caused the large landslide; (2) the existence of thick soft rock belt provides material conditions for the formation of slip surface; (3) certain air conditions provide displacement space for the separation and disintegration of the sliding body, and the landslide is stable at present. Numerical analysis results show that reservoir impoundment will adversely affect the stability of landslide. In order to ensure the normal operation of power station, certain engineering measures must be taken to treat Hejia landslide. After taking measures, years of monitoring data show that the deformation of Hejia landslide tends to be stable, and the current operation is normal, indicating that the engineering treatment measures are reasonable and feasible. [ABSTRACT FROM AUTHOR]

Water–rock interaction is a common phenomenon in rock mass engineering. Water–rock interaction alters the mineralogical and microstructural properties of a rock mass and leads to engineering problems such as leakage, deformation, and failure of a rock mass. To investigate the local leakage in the limestone reservoir, limestone specimens were taken from the underground chamber. In this study, two test conditions were designed: with and without regular replacement of the reservoir water condition. The results indicated that the porosity increased sharply in the early stages of the soaking. But, the rate of increment dropped after 120 d (regular replacement of reservoir water condition) and 90 d (unchanged reservoir water condition), respectively. The pore in the rock was 4.50 mm deep, while the reservoir water was replaced regularly, which is 1.54 times that of the unchanged reservoir water condition (i.e., 2.50 mm), in 360 soaking days. Relatively, the renewal of reservoir water enhanced the chemical reaction. The water–rock interaction altered the mineralogical composition, spatial structure of the crystal, and pore structure of the rock. The change in the longitudinal wave velocity Vm measures the state of pore development. The porosity evolution model for limestone rock was established by considering the impact of dissolution on the spatial structure of the crystal skeleton. The model accurately predicted the variation trend of porosity in the limestone rock under water–rock interaction. [ABSTRACT FROM AUTHOR]