Comparative Study of California Bearing Ratio of Soil Sample Reinforced with Geotextile Fibre Under

IJSTE - International Journal of Science Technology & Engineering | Volume 3 | Issue 04 | October 2016 ISSN (online): 2349-784X

Comparative Study of California Bearing Ratio of Soil Sample Reinforced with Geotextile Fibre under Soaked and Unsoaked Condition Amit Kumar Singh Department of Civil Engineering Kamla Nehru Institute of Technology

Shashank Verma Department of Civil Engineering Kamla Nehru Institute of Technology

Avinash Mishra Department of Civil Engineering Integral University

Saman Khan Department of Civil Engineering Integral University

Abstract Many fibres are in use for ground improvement techniques. Geotextile fibres are a combination of these fibres to create hybrid fibres to meet up the required specification for intended work. The paper analyses the effect of geotextile fibre on soil under soaked and unsoaked condition by comparing the CBR results of the samples. Addition of geotextile fibres enhances the CBR value, but the study concluded that 2 mm penetration depth the increase on reinforcement with geotextile fibre is less in comparison to the increase caused by changing the condition from soaked to unsoaked. While for the 5 mm penetration depth the geotextile fibre reinforced samples exceeded the increase in CBR value more than that achieved by changing the soil condition from soaked to unsoaked.

Keywords: Ground improvement, geotextile fibre, soaked, unsoaked, CBR ________________________________________________________________________________________________________ I.

INTRODUCTION

Incorporation of fibres in soil to improve its properties is in practice for some time. [[1], [2], [3]] The fibre reinforcement is an accepted technique in soil stabilization and ground improvement owing to its ease of use as well as economy.The geotextile fibre reinforcement is recently gaining some attention for ground improvement techniques. [[4], [5], [6]] Geotextiles are made from polymers, such as polypropylene, polyester, polyethylene, polyamies (nylon) and glass fibres composites. These materials are highly resistant to biological and chemical degradation. Natural fibres such as cotton and jute can also be described as geotextiles, although with these materials their use is usually for temporary application.

Geocomposites, in a soil reinforcement context, generally consist of high strength fibers set within a polymer matrix or encased within a polymer skin. The fibres provide the tensile properties for the material while the matrix or skin provides the geometrical shape and protects the fibers from damage. Geocomposites can also be defined as products which combine two or more of the primary function of geotextiles. This is the definition used in this study in which materials combining the reinforcement function and drainage function are considered. These two functions are considered in greater depth below.

II. MATERIALS USED Cohesive soil Clay minerals generally occur in the form of platy particles. The most important property of a clay soil is its plasticity. These is the ability of clay to take up water and for the clay water mass at its optimum consistency to be shaped and to hold that shape after forming forces are removed.

The shear strength behaviour of a clay soil is determined by its consolidation and stress history rather than its density as in the case of cohesion less materials. Most clay soils derive their shear strength from cohesion and friction; however, saturated clays may appear to possess cohesion only and are therefore referred to as "cohesive soils" Geosynthetics used in the Research A nonwoven geotextile developed by DuPontTM (manufacturer) was considered for use in the study. DuPont TMTyparÂŽ SF is a thin, thermally bonded, water permeable nonwoven geotextile made of 100% continuous polypropylene filaments. It is designed to have a combination of a high initial modulus (stiffness), high elongation (typically> 50%) and outstanding uniformity, to give superior performance, to make it resistant to damage and to have excellent filtration properties. DuPont TMTyparÂŽ SF is an

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Comparative Study of California Bearing Ratio of Soil Sample Reinforced with Geotextile Fibre under Soaked and Unsoaked Condition (IJSTE/ Volume 3 / Issue 04 / 013)

isotropic material, which means that its physical properties are the same in all directions. This mirrors the stresses and strains of a typical separation application.

Furthermore, the fact that DuPontTMTyparÂŽ SF is made of 100% polypropylene, makes it resistant to rotting, moisture and chemical attack, particularly alkalis.

III. METHOD AND METHODOLOGY C.B.R. TESTS A number of California bearing test (C.B.R.) were carried out to determine the angle of internal friction cohesion of the Clay soil while containing Non –woven Geotextile with various position. The Sample On which the series of the tests were conducted is as follows: 1) Sample with No Geotextile layer (from Here and after in this Thesis such Soil Sample referred and write as 0G00).

2) Samples with 1 layer of geotextile with Different position in various sample i.e. Single Layer in Upper 1/3 rd region, Single Layer in Middle 1/3rd region and Single Layer in Bottom 1/3rd region (from Here and after in this Thesis such Soil Sample referred and written as 1G0U, 1G0Land 1G0M respectively).

3) Samples with 2 layer of geotextile with Different position in various sample 4) i.e. One Layer in Upper 1/3rd region and One Layer in Middle 1/3rd region, One Layer in Upper 1/3rd region and One Layer in Bottom 1/3rd region, One Layer in bottom 1/3rd region and One Layer in Middle 1/3rd region (from Here and after in this Thesis such Soil Sample referred and write as 2GUM,2GUL and 2GML respectively).

5) Samples with 3 layer of geotextile with Different position in various sample 6) i.e. One Layer in Upper 1/3rd region, One Layer in bottom 1/3rd region and One Layer in Middle 1/3rd region (Such Soil Sample referred and written as 3G00).

C.B.R.is expressed in percentage of force per unit area required to penetrate a soil mass with a circular plunger of 50 mm diameter at the rate of 1.25 mm/minute to that required for corresponding penetration of 2.5 mm and 5.0 mm. where the ratio at 5 mm is consistently higher than that at 2.5 mm, the ratio at 5 mm is used. All tests were conducted on the sample prepared in the laboratory according to the IS 2720(part 16):1987. [[3], [4], [5], [8]&[9]] IV. RESULT AND DISCUSSION

Fig. 1: CBR value at 2 mm penetration depth for soaked and unsoaked soil sample

The figure 1 represent the CBR value for soil sample under soaked and unsoaked condition at 2mm penetration depth. In all the samples of soil with or without geotextile fibre layer the soil samples under unsoaked condition depicted higher CBR values ranging from 20 % - 54 % higher than the soil samples under soaked condition. Though the geotextile fibre layer enhanced the CBR values when compared to the control specimen of 0G00 for both the cases. While on the analysis of soaked and unsoaked based on comparison only samples 3G00 resulted in higher CBR value (54%) on comparison to the 0G00 sample with no geotextile fibre 53%.

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Comparative Study of California Bearing Ratio of Soil Sample Reinforced with Geotextile Fibre under Soaked and Unsoaked Condition (IJSTE/ Volume 3 / Issue 04 / 013)

Fig. 2: CBR value at 5 mm penetration depth for soaked and unsoaked soil sample

The figure 2 represent the CBR value for soil sample under soaked and unsoaked condition at 5 mm penetration depth. In all the samples of soil with or without geotextile fibre layer the soil samples under unsoaked condition depicted higher CBR values ranging from 20 % - 54 % higher than the soil samples under soaked condition on comparison. Though the geotextile fibre layer enhanced the CBR values when compared to the control specimen of 0G00 for both the cases. While on the analysis of soaked and unsoaked based on comparison only sample 1G0L resulted in lower increase in CBR value on comparison to the 0G00 sample with no geotextile fibre.

V. CONCLUSION On comparing the soaked and unsoaked soil samples based on CBR values the unsoaked soil samples performed better than soaked soil samples.Analysing the CBR values at 2.5 mm penetration depth it was found that when soaked and unsoaked samples are compared only two soil samples depicted higher increase in CBR values i.e. 2GUM and 3G00.At 5 mm penetration depth on the analysis of soaked and unsoaked based on comparison only sample 1G0L resulted in lower increase in CBR value (19.95%) on comparison to the 0G00 sample with no geotextile fibre i.e. 26.7%.

In soaked and unsoaked condition the CBR value was enhanced owing to the reinforcement with geotextile fibre. Addition of geotextile fibres enhances the CBR value, but the study concluded that 2.5 mm penetration depth the increase on reinforcement with geotextile fibre is less in comparison to the increase caused by changing the condition from soaked to unsoaked. While for the 5 mm penetration depth the geotextile fibre reinforced samples exceeded the increase in CBR value more than that achieved by changing the soil condition from soaked to unsoaked. Hence the geotextile fibre reinforcement can be used effectively as ground improvement technique.

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Comparative Study of California Bearing Ratio of Soil Sample Reinforced with Geotextile Fibre under Soaked and Unsoaked Condition (IJSTE/ Volume 3 / Issue 04 / 013) [7]

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