Suffusion is the main and prominent form of seepage stability in deep alluvium foundation. It is of great theoretical and practical significance to carry out relevant experiments and theoretical studies on suffusion in deep alluvium foundation for the safety of major hydropower projects under construction and to be built in China. In this paper

firstly

it is pointed out that the mechanisms of backward erosion piping and suffusion are completely different

so they cannot be confused together. Compared with backward erosion piping

suffusion is more subtle

and its mechanism is more complex. Secondly

the research of suffusion is summarized in detail from three aspects: geometric condition

hydraulic condition and mathematical model. Finally

combined with the lower Yarlung Tsangpo River hydropower development and other major national projects

the following aspects should be emphasized

including the evaluation of internal stability in deep alluvium foundation

the mechanism of suffusion initiation and progression under extreme conditions

complex seepage conditions and formation conditions

the evaluation and control of suffusion time effect and its long-term impact

and the experimental and theoretical research of suffusion constitutive relation and its mathematical model.