Practice of reinforced embankment on hard foundation - a case study of Phitsanulok, Thailand
Link to publisher version (URL)
A full scale reinforced test embankment was designed and constructed by Department of Highways (DOH) on hard foundation (i.e. Soil stratum containing relatively stiff to very stiff clay) in Phitsanulok Province, Thailand. Two types of reinforcements were used. One side, called reinforced steep slope (RSS) with folded polymer facing at an angle of 70 degrees from the horizontal, was reinforced with polymeric reinforcements consisting of polyester (PET), polypropylene (PP) and high density polyethelene (HDPE). The other side, called mechanically stabilized earth wall (MSEW) with vertical segmental concrete facing, was reinforced with metallic reinforcement consisting of metallic strips (MS) and steel wire grids (SWG). The behaviour of the RSS and MSEW slopes were observed, back-analysed by sensitivity analysis and compared with the predictions from FEM PLAXIS 3D simulations. As expected the vertical settlements were very small for the hard foundation. The corresponding lateral movements from the RSS side were much larger than the MSEW side due to the higher stiffnesses of the former than the later. The magnitudes of the reinforcing material stiffnesses decrease in the following order: metallic strips (MS), steel wire grids (SWG), polypropylene (PP) high density polyethelene (HDPE) and polyester (PET). The polymeric reinforcements have comparable ultimate tensile strengths at 100 KN/m. The predictions from the FEM PLAXIS 3D simulations were in good agreement with the field measurements in terms of vertical and lateral deformations as well as strains in the reinforcements.