A Model Study on Accelerated Consolidation of Coir Reinforced Lateritic Lithomarge Soil Blends with Vertical Sand Drains for Pavement Foundations

George Varghese, Hegde Ramakrishna, A.G. Nirmal Kumar, L. Durga Prashanth, G. Santosh

Department of Civil Engineering, National Institute of Technology, India.

DOI: 10.4236/ojss.2012.23038                

Abstract

Sub-grade soils of lateritic origin 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. This work deals with accelerated consolidation of un-reinforced and coir-rein- forced lateritic lithomargic soil blends, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50 kg (0.0013 N/mm²) to 500 kg (0.013N/mm²) on soil specimens prepared in circular ferro-cement moulds. It was observed that at lower preloads up to 200kg, across the blends, the relative increase in consolidation (R_ct) for randomly reinforced soil with vertical drains was sig-nificantly higher than that of un-reinforced soil without vertical drains, with an average value of 124.8%. Also, the Rct for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with an average value of 103.9%. In the case of higher preloads, the R_ct values for randomly reinforced soil with vertical drains were moderate with an average value of 30.88%, while the same for un-reinforced soil with vertical drains was about 20.4%. The aspect-ratio of coir fibers used was 1:275.

Keywords

Vertical Sand Drains; Accelerated Consolidation; Settlement; Coir Reinforcement; Laterite; Shedi;Lithomarge

Conflicts of Interest

The authors declare no conflicts of interest.

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