Evaluation of Bearing Capacity of Fly-Ash Highway Subgrade Based on Model Test

Based on the mechanical properties of fly ash (FA) and the similarity theory, a small-scale geomechanical model was virtually built for evaluating the actual bearing capacity of FA embankments. The embankment model was divided into two sides: the right was covered by a concrete surface and the left was uncovered. The monitoring results of stress and displacement in different depths of the model embankment during the loading process were both presented. In the process of testing on the covered right side, both the additional stress and displacement of soil in different depths increased with an increasing load. There was a significant increase of displacement under large loading in different depths of the covered side, which suggested that plastic failure may happen and would gradually develop from bottom to top. The limit-bearing capacity of the FA embankment covered by concrete surface yield from the model test can be adopted as 419 kN that was assumed to fulfil the requirements of traffic load. As to the uncovered left side, plastic failure was very likely to occur in the soil beneath the bearing plate with a certain applied load, which caused a decrease of additional stress. Plastic failure gradually develops from top to bottom of the uncovered side. The limit-bearing capacity of the FA embankment without the concrete surface can be taken as 193 kN that may not meet the requirement for the overloading of vehicles.