Evaluation of the bearing capacity improvement of geogrid mattress foundations

Mattress foundations using geogrids are often used to improve the supporting capability of a soft soil foundation. It is well known that the vertical load applied on a geogrid-mattress foundation is transmitted to the supporting soil over a wider area, thus, improving the soils ability to support the foundation load. In order to clarify the improvement in bearing capacity due to geogrid-mattress foundations, a series of model loading tests on a geogrid-mattresses were carried out, with particular reference to their thickness and stiffness. In addition, a method of evaluating bearing capacity improvement is presented based on the experimental and theoretical considerations. It was found that the bearing capacity improvement can be formulated as a function of width of loading normalized by the effective width in the supporting soil layer.