Model Tests on Coir Geotextile-Encased Stone Columns with Tyre Crumb-Infilled Basal Coir Geocell

Abstract

An encased stone column with a geocell mattress can serve as a flexible pile raft system, helping in the uniform transfer of embankment load to the underlying foundation soil, improving their behavior. The efficiency of encasement and geocell depends on various factors, among which the material stiffness is an important one. The present study addresses the global concerns over excessive use of synthetic materials in soil by replacing the conventional synthetic forms of reinforcement (geotextile/geocell) with locally available coir fibers. Furthermore, to enhance the composite system s sustainability, the potential replacement of the conventional geocell infill materials like stone and aggregates by waste rubber tyre crumbs is also investigated. Laboratory scale model tests were conducted on a single encased stone column installed in a soft clay bed with coir geocell mattresses as basal reinforcement, adopting the unit cell concept. The static vertical load was applied at a constant strain rate of 0.06\xa0mm/min to simulate the field conditions, and the load settlement responses were recorded up to a settlement of 12\xa0mm. The results show that the composite system significantly improved the load settlement response of soft soils by developing more uniform load settlement profiles. It was also observed that the partial replacement of crumb rubber up to 10% as geocell infill material improved the interface frictional behavior and the load-carrying capacity of the foundation, thereby forming a sustainable solution for the environmental hazard due to the accumulation of used rubber tyres.