Effects of Soaking Process on CBR Behavior of Geotextile Reinforced Clay with Sand Cushion

Clay, which was excavated from the river, was difficult to reuse because of the massive property changes when changing its water content. When being saturated, the clay becomes looser and softer, inducing a significant reduction in the bearing capacity. To improve those disadvantages, the clay was reinforced by the nonwoven geotextile with a sandwich sand layer. Using the California Bearing Ratio (CBR) tests, the reinforced clay's bearing capacity behavior with a sand cushion under soaking condition was investigated. The result reveals that the sandwich sand layer significantly improved the CBR value of the reinforced riverbed clay. After 96 hours of soaking, the CBR value of reinforced specimens was as high as 1.5-2.8 times that of the un-reinforced specimen. Regarding the bearing capacity reduction after soaking, the CBR value of unreinforced riverbed clay was less than 3%, which reduced up to 73.1% of its bearing capacity before soaking. In contrast, the CBR reductions of reinforced specimens were varied from 42.2-60.8% depending on the thickness of the sand layer. When increasing the sand height, the CBR value went up, especially for soaking specimens. The optimal dry mass ratio between sand and soil was 0.1 in other that the CBR got the highest value.