Performance assessment of mechanically stabilised earth walls with sustainable backfills: experimental and numerical approach

The growing depletion of natural geomaterials has forced scientists and engineers to look for alternate sustainable backfill materials in large-scale practical applications. The study presents the experimental and numerical investigation on the performance of two sustainable backfills, namely steel slag and construction and demolition waste (CDW) for possible Mechanically Stabilized Earth (MSE) wall backfill application. A detailed characterization followed by the performance evaluation of the materials using extensive laboratory experiments, encompassing the strength and drainage criteria is presented. Results of the triaxial and California Bearing Ratio (CBR) strength tests highlighted the superior performance of the sustainable backfill materials as compared to the traditional backfill material. The adequate drainage capacity of slag and CDW reflected encouraging possibility of utilising the materials as alternate backfills. In addition, the strength enhancement options of sustainable backfills using geogrid reinforcement have been evaluated. Finally, the feasibility of utilising the materials in a prototype MSE wall was investigated with the help of finite element numerical analysis. Hardening Soil model was used to effectively capture the non-linear stress-strain behaviour of these materials. Results obtained from finite element analysis demonstrated multiple benefits of sustainable backfill materials. In comparison to the standard backfill, MSE walls with slag and CDW backfill demonstrated 56% and 70% reductions in horizontal wall displacements, respectively. Moreover, lower reinforcement strains were observed in walls with sustainable backfills.