This paper briefly describes the particularity and design difficulty of hydropower engineering slopes and general situation of hydropower engineering slope design in China. According to the stability property, a slope structure system is established. A systematic design method for high slope engineering based on slope structure characteristics and Chinese engineering experience is proposed; that is, a design process with four stages and 11 steps. Additionally, the research tasks and methods of each design stage and the research content of each step are introduced. It is believed that identifying and determining the slope structure type in the engineering area is a key step in the slope design process, and the key objects of the design are the poorly stable Class III and Class IV slopes and unstable Class V slopes. The design method has a complete system structure, detailed and specific content, and strong operability and guidance.
People have been studying the deformation and failure of slopes since the beginning of engineering practices. In the first half of the 20th century, a limit equilibrium analysis method focusing on the failure mechanism of landslide or soil slope was gradually formed and improved. In the second half of the 20th century, the rapid development of rock mechanics and numerical analysis methods provided a theoretical basis for slope design [1]. In 1973, the book "Rock Slope Engineering" edited by E. Hoek and J.W Bray, was published, and the system design method based on mining engineering slope was first proposed [2]. A hydropower slope project, especially the slope of a "high dam and large reservoir", is vulnerable to the influence of reservoir impoundment, reservoir water level fluctuation, dam flood discharge erosion, and atomization precipitation. During the operation of a project, instability and damage often occur, affecting the normal safe operation of the project and even causing engineering disasters or huge social disasters, such as the landslide of the Vajont Reservoir in Italy in 1963. Thus, slope design is difficult. To make rational use of clean and renewable water resources, China, like other countries in the world, has built many high dam and large reservoir power stations in recent decades. According to incomplete statistics, more than 190 high dams over 100 m tall have been designed and built in China, of which there are more than 20 high dams over 200 m tall, and the maximum dam height is 305 m [3]. There are 137 reservoirs with more than 1 billion cubic meters of volume, including 16 reservoirs with more than 10 billion cubic meters of volume, and the largest reservoir has a volume of 39.3 billion cubic meters. Additionally, many high slopes with rarely seen in the world have been designed. According to the preliminary statistics, there are 22 super-high slopes over 300 m tall in the hub area. Among them, there are four slopes with heights in the range of 600–700 m, and the maximum height is 695 m. Slope design plays a key role in engineering design and construction. However, most of the "high dam and large reservoir" projects in China are located in the central and western regions, such as the Yangtze River, Jinsha River, Lancang River, Yalong River, Dadu River, Yellow River, and Hongshui River, which are close to the Qinghai-Tibet Plateau. In these areas, the terrain is elevated, the mountains are high, the valleys are deep, the neotectonics and the seismic activities are strong, the geological disasters are frequent, the topographical and geological conditions are extremely complex, and engineering high slope stability is particularly important. During the construction and operation of hydropower projects, there have been many serious slope instability incidents that have caused casualties, increased investments, and extended construction periods. These incidents have affected the normal and safe operation of the projects. High slope stability problems have affected and restricted the development of hydraulic resources and the process of engineering construction. Therefore, it is of great significance to summarize and draw lessons from the design experience of hydropower high slopes in China. Combined with engineering practices in China, this paper systematically summarizes and integrates the existing research results and design experience. Additionally, design procedures and methods for Chinese high slope hydropower projects are discussed for reference.
