Abstract: Most of slopes involve groundwater, and seepage is one of the key factors of slope stability. A series of equations deduced based on classical soil mechanics theory are presented to determine the slope’s self-stability critical height in consideration of surcharge and steady groundwater seepage. The application of the classical theory is thus extended. Groundwater seepage is found out not to change the locations of potential slip surfaces but to decrease the self-stability critical height of slopes. The equations presented in this research are suitable to calculate the critical height for natural slopes, fill slopes, embankment slopes, slippage slopes with known slip locations, excavation slopes and so on.

Key words: slope, self-stability, critical height, seepage analysis, flow nets