Evaluation of uncertainties in the resistance provided by slender reinforcement for slope stabilization

The limit soil pressure is vital for computing the maximum, or limit lateral resistance that reinforcing members can provide for stabilizing a slope. Different methods exist to predict the maximum pressure that soil can sustain before failing in a plastic mode when stabilizing reinforcing members are present in a slope. However, the limit soil pressure predicted from the available methods for a specific soil condition varies over a wide range. This wide range in predicted limit soil pressure introduces uncertainty in current engineering practice for designing and stabilizing slopes with slender reinforcing members, which often results in conservative design and higher overall costs than may be necessary. The objectives of this research work were to quantify and reduce the degree of uncertainty in the resistance provided by slender reinforcement for slope stabilization with particular focus on the limit soil pressure.;Uncertainty in the limit soil pressure was reduced by performing: (1) Parametric analyses to evaluate the importance of parameters affecting the stability of slopes reinforced with slender reinforcement, (2) Analysis and evaluation of a case study of a failed slope that was reinforced with a single cluster of slender reinforcement, (3) Monitoring the long-term performance of failed slopes stabilized with slender reinforcing members, and (4) Calibrating the current analysis methodology based on observed field performance.;Results of the parametric analyses show that use of reinforcement where the structural capacity controls the resistance of the reinforcement over most of its length significantly reduces the degree of uncertainty in factor of safety for reinforced slopes. Results from the long-term monitoring program show that all the stabilized slopes are performing well, and that the reinforcing members have mobilized both bending and axial resistance.;The current analysis methodology was successfully calibrated to match the field performance of one site by modifying the limit soil pressure. The range in limit soil pressures required to produce factors of safety consistent with the observed field performance was approximately one-half that suggested by available methods. The limit soil pressures predicted by Ito and Matsui and 3 times the pressure defined by Ito and Matsui provide a lower and upper bound, respectively. Attempts to calibrate the current analysis methodology incorporating axial resistance for reinforcing members, in addition to the lateral resistance, were unsuccessful.