To analyze the stability of a thick overburden slope under the effect of transient pore pressure

a method for calculating transient pore pressure was developed based on the formation and distribution of transient saturated area. A modification on Bishop limited equilibrium method was made with the consideration of the influence of transient pore pressure on stability

and a routine using VB was programmed. The proposed procedure was employed to analyze stability of an overburden slope along Ru-Chen expressway in two calculation conditions whether the transient water pressure was considered or not. The results show that the greater the thickness of transient saturated zone

the smaller the safety factor of slope. The lower safety factor exists in slope affected by transient water pressure under the same thickness of transient saturated zone. With the expansion of transient saturation zone

the decrease rate of slope safety factor keeps increasing

up to 39.79%. The potential sliding surface will be tangent to the wetting front and becomes deeper if the thickness of transient saturated area is over 4 meters.