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Summer Research Fellowship Programme of India's Science Academies

Numerical study on the effect on granular slopes stabilised with synthetic tyre-fibers

Maitri Debnath

Department of Civil Engineering, 3rd Year, 6th Semester, NIT Agartala, Tripura, 799046

Prof. Ashish Juneja

Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai, 400076

Abstract

This project aims to compare the drained shear strength characteristics of fine Yamuna sand and when the sand is mixed with tyre-fibres at a few different densities. This sand is otherwise known to have poor load carrying capacity with easily erodible particles. Literature on tyre-fibres suggests that when these light-weight materials are used with some silty or clayey soils can cause the soil to improve its mechanical strength. It is however not clear that similar effect can be observed when the fibres are used with fine sand. In case this project is successful, then it can solve a major environment concern which is the disposal of such wastes in the future. In this study, the relation between relative density and peak angle of friction was investigated by using direct shear and simple shear tests at low confining pressures. Results with and without the tyre-fibres were obtained. It is envisaged that with the improved strength, some historical slope stability problems can be resolved, which have failed in the past. For this, a commercially available program (e.g. Talren) was used. The relation between density and peak angle of friction using direct shear tests has been obtained. For this, properties of Yamuna sand were first investigated. Tests were then carried out on the sand compacted in 60 mm x 60 mm x 20 mm size moulds, and at densities which ranged from 35% to 85% in five steps. All tests were conducted on four low normal stresses which varied from 10 to 40 kPa. The output was gathered in graphical forms to observe the patterns of different parameters. Preliminary test results suggest that the peak angle of friction increased as the sample density increased. In the project work, similar direct shear tests were carried out when sand sample is mixed with crushed tyre-fibres (by percent weight of dry soil) and its results compared.

 

Keywords: drained shear strength parameters; density; direct shear test ; peak angle of friction; tyre fibres;

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The number of scrap tyres is increasing every year due to the increase in the population of vehicles both in the developing countries. With the development of societies and use of various vehicles the tyres are now a challenging source of waste. Due to the large volume produced and the components in the tyre causes serious problems in the environment. Because of wear and irreparable damage the waste tyres are no longer suitable for use on vehicles. As tyres are highly durable and non-biodegradable, they can consume valued space in landfills. According to a report, 299 million waste tyres abandoned in the environment in USA in 2005. The number of disposed scrap tyres was 103 million in Japan, 28 million in Canada, 20 million in South Korea, and 14 million in the UK. Tyres are a breeding ground for mosquitoes, which spread serious diseases. Tyres have potential for tyre fires as shown in Fig 1 (a) which produce acid smoke that is harmful to humans and the environment. Tyres take up landfill as shown in space as shown in Fig 1 (b) and the land is becoming scarce.

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