Abstract: According to the mechanism of “Ripping up the Riverbed” and exposing mode of clay block, building four exposing analytical model of clay block, that is, (1) Due to the role of force moment leading to break clay block model, (2) The forces acting on clay block in the depth direction and shearing force of clay block fractured surface balance model, (3) Due to the role of force moment leading to whole piece of clay block expose model, (4) The forces acting on clay block in the depth direction and adhesive force of clay block boundary balance model. Considering the combined effect factors of clay block exposing, calculate separately the water and sediment indicators of each clay block exposing model, finally, the minimum value of the calculated results as critical water and sediment on "Ripping up the bottom ". The results of this study provide a theoretical support for discriminating whether a flood led to the phenomenon of "Ripping the bottom”, also provides the possibility of real-time data acquisition on “Ripping up the bottom”.