Abstract: This case history presents the treatment of expansive soil slope instability hazards near a bridge construction site. From the soil stratigraphy within the affected slopes, physical and mechanical properties of various soil strata as well as the hydrogeological conditions, it is identified that the initiation and the development of the fissures are the main factors that cause adverse movement of the slope in expansive soils.  The limits of the weak zone can be estimated from the locations of the cracks near the bridge piers and the transverse tension cracks near the abutment pavement. The stability of the affected zones is evaluated by the software GEOSLOPE. Based on the failed slopes at the bridge site, the shear strength parameters are backanalyzed using the limit equilibrium theory. The rehabilitation program includes antislope piers with a rectangular crosssection, local unloading, as well surface drainage improvements.

Key words: Landslides, Expansive Soils, Driving Force in the Slope, BackAnalysis, AntiSlope Failure Piers