Performance Analysis of Slopes Reinforced Using Micropiles

Abstract

This paper presents two case studies of performance analysis of slopes reinforced using micropiles. Finite-element analyses were performed using the shear-strength reduction method for limited equilibrium analysis (i.e., factor of safety). Different mitigation designs for micropiles were compared in each case, where Case 1 included underpinning and strengthening with inverted L-shaped micropiles and Case 2 included reinforcing with gantry-style micropiles. In this study, performance measures, including reinforcement efficiency, deformation distribution, settlement of supported walls, and safety factor, were carefully examined and are here presented in detail. In summary, the proposed micropile applications were found to provide foundation stability and inhibit displacement in order to strengthen the studied slope. Wall underpinning with inverted L-shaped micropiles was found to further improve the safety factor, total displacement, and soil subsidence. In both cases, the direct benefit of installing single-row vertical micropiles to form a retaining wall in the ground was enhancement of the safety factor by approximately 6–4% and reduction of maximum displacement is significantly reduced from approximately 53–67%. In Case 2, micropiles with a gantry configuration were found to enhance the safety factor by a maximum of approximately 59% and to reduce total displacement and soil subsidence by approximately 73 and 84%, respectively.