Soil reinforcement that is not prestressed develops no loads that will improve slope stability until the slope moves, inducing strain in the reinforcement. Limit equilibrium analyses can be used to compute the factor of safety of reinforced slopes based on selected reinforcement forces (usually a fraction of the reinforcement strength), but they give no indication of the amount of deformation of the slope that will occur, or the force that will develop in the reinforcing under working conditions. Prestressed anchors have the advantage that they apply stabilizing forces without requiring deformation of the slope. Further, these forces remain nearly constant, independent of slope deformation, due to the large compliance of the high-strength steel tendons used in the anchors. The long-term performance of slopes reinforced by either type of reinforcement is affected by possible reduction in the capacity of the reinforcement as a result of corrosion or creep, by changes in soil strength as a result of softening or consolidation, and by changes in the reinforcement loads as a result of slope movements or changes in water pressure within the slope. Two examples illustrate these possibilities. Both involve the use of steel reinforcement, so corrosion is a factor in these cases, but not creep.
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