Based on the dump slope engineering geotechnical conditions

analyses of the instability mode and main impact factors of dump slope with multi-step in details were taken

and stability conditions were simulated by the limit equilibrium method and the finite element strength reduction method.The results show that the slope may slide along the humus layer

and the plastic zone passes through the humus layer firstly

then produces two upward plastic changing belts.The plastic zone along the central bench-shape slope develops earlier while the other one which passes through the top of the slope lags relatively.The more ground water level rises

the larger additional displacement of the slope will be

then the vertical tensile stress zone has the trend of extending which make the slope more unsafe.The slope sections where displacement is zero or changes little should be avoided when monitor and analysis of slope stability is based on the the vertical incremental displacement trend.The level incremental displacement is focused on the bottom of the slope

and the upheaval is produced on the position of the lower middle of slope

finally this kind of discontinuous transition increases the possibility of slope instability.