A model study on accelerated consolidation of coir reinforced laterite and blended shedi soil with vertical sand drains for pavement foundations

Abstract

Sub-grade soils of lateritic origin are frequently encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. Coir is a natural fiber that can be used in place of geosynthetics and geogrids, and it is biodegradable and environment friendly. This work deals with the accelerated consolidation of un-reinforced and coir-reinforced laterite and blended lithomargic soils, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50kg (0.0013 N/mm2) to 500kg (0.013N/mm2) using circular ferro-cement moulds. It was observed that at lower preloads up to 300kg, the relative increase in consolidation (Cr) for randomly reinforced soil with vertical drains was significantly higher than that of un-reinforced soil without vertical drains. Also, the Cr for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with values above 38.71%. However, in the case of higher preloads of 450kg and 500kg, the Cr for randomly reinforced soil with vertical drains was insignificant, and the Cr for un-reinforced soil with vertical drains remained slightly higher at around 9.59% for similar comparisons. The aspect-ratio of coir fibers used was 1: 275. 2012 Cafet-Innova Technical Society. All rights reserved.