Abstract: The mechanism and discriminant formula of foundation liquefaction under vibration are deduced by means of effective stress theory analysis and dynamic pore pressure stress-strain model. Combining FLAC3D with Finn model， the fluid-solid coupling calculation are made. FISH language was adopted to write the formula of the excess pore pressure ratio to judge the foundation liquefaction during earthquake. According to the variation of stress-strain， pore pressure and excess pore pressure ratio， the change of the saturation surface of the initial dam is analyzed， and whether the foundation is liquefied considering seepage is analyzed in detail. The pore pressure， acceleration， settlement displacement and excess pore pressure ratio at different locations are obtained， and functional relationship between excess pore pressure ratio and overlying strata pressure was achieved by regression. The above analysis provides a reference basis for the safe operation of the tailings reservoir， provides important basic data for the construction and use of the tailings reservoir in the later stage， and summarizes the relationship between excess pore pressure ratio and overburden pressure by means of linear regression. All these provide a convenient method for quickly judging the liquefaction area of the tailings reservoir.

Key words: Goaf, Fluid-solid coupling, Tailing pond, Liquefaction analysis, Regression analysis