The Wudongde Hydropower Station is the backbone power source of the West-to-East power transmission. It is a first-class (1) project with a installed capacity of 10,20MW and ranks seventh in the world. It has a concrete double-curved arch dam with a maximum height of 265 m. The high arch dam has the characteristics of large drop, large flood discharge flow and narrow river valley, and the atomization problem is outstanding. To investigate the impact of infiltration of discharge induced atomized flow on slope stability, the theory of saturated-unsaturated seepage and its coupling with stress is adopted. The infiltration of discharge induced atomized flow is considered as flow boundary condition. Based on the covering range of atomized flow and its intensity, the transient seepage in slope and its variation process subjected to atomized flow condition is calculated. The influences of atomized flow and up rise of water level on slope stability are also quantitatively evaluated. The results show that the infiltration depth and its impact area have close relevance to the slope shape and atomized flow intensity. According to the frequency of floods in a hundred years, the infiltration depth of the water plunge pool can be up to 60m. Due to the impact of atomized flow, the plastic zone has a major extension compared to construction period and the plastic yield degree is also higher. After the effect of atomized flow, the factor of safety for slope is lowered greatly. Finally, the countermeasures are proposed based on the calculation results. The project can provide reference and basis for other projects.

1. Introduction

Flood discharge atomization refers to the phenomenon of unnatural rainfall and water mist diffusion formed by large hydropower stations during flood discharge. Because its rainfall intensity far exceeds the natural rainfall record, it has a certain impact on the downstream building safety, bank slope protection, road traffic and the surrounding environment. Through the quantitative analysis of atomization rainfall, on the one hand, it can be used to demonstrate whether the overall layout of the whole hub, the energy dissipation mode of flood discharge buildings and the protection of downstream bank slope are reasonable; on the other hand, it can predict the distribution of flood discharge atomization under future flood conditions, so as to take necessary engineering preventive measures to ensure the safe operation of the project.

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