Settlement of footings at the crest of reinforced slopes subjected to toe unloading

Abstract

To investigate the effectiveness and limitations of using a reinforced earth slab to mitigate excessive footing settlements induced by an unloading at the slope toe, two-dimensional model slope tests were performed. Model slopes sustaining a constant footing load at the slope crest were brought to failure by progressively unloading at the slope toe. A rigid wall was jointed to a screw jack to apply constant displacement rate translational movement of the rigid wall to simulate typical conditions of slope toe excavation. Test results revealed that the toe unloading-induced settlement of a footing can be significantly reduced by using two layers of geosynthetic reinforcement under the footing, provided that the height of toe unloading (H) is less than the threshold value (Hc). For a cohesionless slope subjected to a footing load at the crest, the threshold unloading height can be significantly increased (by 64%) by incorporating two layers of geosynthetic reinforcement under the footing. Test results also revealed that both the stability of a footing and the locus of points of maximum tensile reinforcement force are strongly influenced by the location of the active slip plane developed behind the zone of toe unloading.