An experimental investigation of soil arching within basal reinforced and unreinforced piled embankments

Geotechnical engineers face several challenges when constructing embankments over soft soils. These include potential bearing failure, intolerable settlement, and global or local instability. Piled embankments provide an economic and effective method to construct roads on soft soils. Soil arching developed within such embankments has significant influence on its behavior. A total of 15 model tests were conducted to evaluate the effects of pile–subsoil relative displacement, embankment height, cap beam width and clear spacing, and geosynthetics with different tensile strengths on stress concentration ratios and settlements in the embankments. The test results indicate that stress concentration ratio varies with pile–subsoil relative displacement and has upper and lower bounds. A higher ratio of embankment height to cap beam clear spacing, as well as a higher ratio of cap beam width to clear spacing, would result in a higher stress concentration ratio. The inclusion of a geosynthetic membrane can increase the stress concentration ratio. When the embankment height to the cap beam clear spacing ratio, h/s, is less than 1.4, apparent differential settlements may occur on the surface of embankment. When h/s is greater than 1.6, however, no apparent differential settlements will occur on the embankment surface. In addition, experimental results were also compared to several current design methods.