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

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 (H_c). 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.