Effects of Sand Cushion with Geotextile Reinforcement on Improving Consolidation Behavior of Soft Clay

In order to reduce the cost of constructing roads in rural areas of the Mekong Delta, the roadbeds were constructed by consolidating very soft clay excavated from the bottoms of local channels and rivers. This paper describes a method for enhancing soil through the use of geotextile layers and sand cushions. Using a series of one-dimensional consolidation experiments on soft clay with and without sand cushion inclusion, the consolidation behavior of the improved soil with varying sand cushion layer thickness and consolidation pressure was determined. In addition, the side friction pressure between soil and the inner side of consolidation rings was also measured to quantify its effects on the test results. In comparison to unreinforced clay, the appearance of a geotextile sand cushion reduces the primary consolidation period by 20–40% and increases the coefficient of consolidation by up to 18%. These findings comprise the fundamental theory for the design and construction of road foundations.