Slope stability analysis of rockfill dam by 3-D FEM strength reduction method

3-D FEM strength reduction method is used to analyze the slope stability of Lianghekou rockfill dam.We adopt the ratio of resultant displacement vectors of typical points to strength reduction factor as the dam slope failure criteria,and the resultant displacement vectors consist of stream-direction displacements and vertical ones.When the ratio appears a sudden change or reaches a limit value,the dam slope is in the limit balance state and the strength reduction coefficient is suggested to be safety factor of the slope.The position and shape of potential sliding surface are studied by displacement vector contour map in the critical failure state.It is showed that the safety factor calculated by strength reduction is slightly smaller than that calculated by slice method,and resultant displacement vector′s variation trend has clear physical meanings and reliable results as the failure criteria.Moreover,the research shows that in a certain range,the more grades of construction load,the larger of the stability safety factor;the more grades of impoundment,the more stable the dam slope is.