Model Studies on Geocell-Reinforced Fly Ash Bed Overlying Soft Clay

Abstract

This paper addresses the effectiveness of geocell mattress prepared with waste plastic bottles with fly ash as a filling material overlying soft clay bed through laboratory model tests. The test beds were subjected to loading by means of a square rigid steel plate as a footing. The effect of height and width of geocell mattress as well as basal bamboo geogrid underneath geocell mattress on overall performance of the system in terms of footing pressure, settlement, and the adjacent surface deformation (heave/settlement) has been systematically studied through a series of tests. Test results indicate around twofold increases in the bearing pressure by placing a jute geotextile separator beneath the unreinforced fly ash bed, whereas reinforcing the fly ash bed with geocell mattress in presence of a basal bamboo geogrid and jute geotextile separator can produce sevenfold increases in the footing pressure. Inclusion of a basal bamboo geogrid improves overall behavior of the reinforced bed. No surface deformation occurred in the unreinforced beds. Inclusion of a geocell mattress improves the footing pressure, but creates surface deformation (heave/settlement). Increase in height as well as width of geocell mattress not only diminishes the surface heaving but also increases the footing pressure. As the present study carries limitation of boundary and scale effects, the quantitative results must be extrapolated by dimensional analysis before use in practical applications or a field study is required. However, the qualitative results encourage the use of waste plastic bottles for soft ground improvement, which in turn may solve the disposal issue to a certain extent.