A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering

Thesis (M.Sc.) - Asian Institute of Technology, 2000

Numerical models for the interaction between the hexagonal wire mesh reinforcement and silty sand backfill for the laboratory pullout and direct shear tests have been carried out. Finite element method (FEM) under plane strain condition using PLAXIS and SAGE CRISP computer softwares were utilized with the existing laboratory data. The differences were found between the calculated and the theoretically-computed interaction coefficients because of some limitations. The calculated interaction coefficients for the pullout mechanism were 0.5 and 0.3 for galvanized and PVC-coated hexagonal wire mesh, respectively. The calculated interaction coefficient for the direct shear mechanism was 0.9 for both types of the wire mesh. · Comparison of the modeling results between two computer softwares was given for the modeling in the l~boratory. The calculated interaction coefficients were then applied on the modeling of full scale test embankment on soft ground in AIT campus to investigate the interaction mechanism within the embankment. The numerical simulation techniques adopted in this study reasonably predicted the overall behavior of the reinforced embankment system on soft foundation. Nevertheless, there were some simulations deviating from the measured field data, and they have been explained concerning the probable factors contributing to the discrepancies including the inherent limitations of the simulation techniques. Most of the interaction modes obtained from the analysis, at working stress conditions, were the direct shear interaction mode although some zones indicated pullout mode. Finally, a comparison with previous test embankments using steel grids and polymer grids reinforcements was made. It was found that higher reinforced soil system stiffness has some characteristics different from lower reinforced soil system stiffness. For the interaction mechanisms, the direct shear interaction mode generally dominates the behavior at service condition with some zones in the reinforced mass having pullout interaction mode. The higher reinforced soil system stiffoess tends to have more pullout zones.