Stability analysis of 3D geosynthetic–reinforced earth structures composed of nonhomogeneous cohesive backfills

Abstract

Soils are assumed to be homogeneous in most designs of geosynthetic-reinforced earth structures (GRESs), thus ignoring the influences of the possible cohesion and cohesion nonhomogeneity of backfills. However, the actual stability of GRESs is directly influenced by the presence of cohesion and cohesion nonhomogeneity of backfills along with the three-dimensional (3D) character of GRESs. In the present study, a chart-based stability analysis of a 3D GRES composed of nonhomogeneous cohesive backfills subjected to the seismic excitation/pore water pressure is conducted by means of the limit analysis method. Work rates by seismic forces and pore water pressure are calculated based on the pseudo-static method and the pore water pressure coefficient, respectively; thereafter the energy balance equation is derived by equating the external work rates of the soil weight and seismic forces/pore water pressure to the sum of the work rate of the geosynthetics and internal energy dissipation caused by soil cohesion. The analytical expression of the required unfactored reinforcement strength is derived and the optimized solutions are consequently captured. A comparison is drawn to verify the present study and a parametric analysis is conducted thereafter to investigate the effects of the 3D character, cohesion nonhomogeneity, seismic excitation and pore water pressure on the stability of GRESs. Finally, a set of stability charts considering the 3D effects, cohesion nonhomogeneity, seismic force and pore water pressure on long-term stability is proposed for preliminary design purposes.