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Influence of positions of the geotextile on the load-settlement behaviour of circular footing resting on single stone column by 2D Plaxis software

Yadav J. S., Kumar K., Dutta R. K., Garg A.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 107, nr 2

75--85

EN

Purpose: This study aims to study the load – settlement behaviour of circular footing rested on encased single stone column. Design/methodology/approach: The effect of vertical, horizontal and combined verticalhorizontal encasement of stone column on the load carrying capacity were examined numerically. The effect of stone column dimension (80 mm and 100 mm), length (400 mm and 500 mm), and spacing of reinforcement on the load carrying capacity and reinforcement ratio were assessed. Findings: The obtained results revealed that the load carrying capacity of geotextile encased stone columns are more than ordinary stone columns. For vertically encased stone columns as the diameter increases, the advantage of encasement decreases. Whereas, for horizontally encased stone column and combined vertical- horizontal encased stone column, the performance of encasement intensifies as the diameter of stone column increases. The improvement in the load carrying capacity of clay bed reinforced with combined verticalhorizontal encased stone columns are higher than vertical encased stone columns or horizontal encased stone column. The maximum performance of encasement was observed for VHESC1 of D = 80 mm. Research limitations/implications: For this study, the diameter of footing and stone column was kept same. The interface strength factor between stone column and clay bed was not considered. Practical implications: The encased stone column could be use improve the laod bearing capacity of weak soils. Originality/value: Many studies are available in literature regarding use of geosynthetic as vertical encasement and horizontal encasement of stone column. The study on combined effect of vertical and horizontal encasement of stone column on load carrying capacity of weak soil is very minimal. Keeping this in view, the present work was carried out.

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A study on alkali resistant glass fibre concrete and its exposure to elevated temperatures

Hussain S., Yadav J. S.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 103, nr 1

5--15

EN

Purpose: Cement concrete is characterized as brittle in nature, the loading capacity of which is completely lost once failure is initiated. This characteristic, which limits the application of the material, can in one way be overcome by the addition of some small amount of short randomly distributed fibers (steel, glass, synthetic). Design/methodology/approach: The present study deals with the inclusion of alkali resistant glass fibers in concrete by percentage weight of cement. The mechanical properties such as compressive strength and split tensile strength have been studied after exposing the concrete samples to elevated temperatures of up to 500°C. Water binder ratios of 0.4, 0.45, 0.5, 0.55 and 0.6 have been used to prepare design mix proportions of concrete to achieve a characteristic strength of 30 MPa. The depth of carbonation post elevated temperature exposure has been measured by subjecting the concrete samples to an accelerated carbonation (5%) condition in a controlled chamber. Findings: Conclusions have been drawn in accordance to the effect of fiber replacement and temperature increment. The concrete mixes with fiber content of 1% by weight of cement had shown better strength in compression and tension compared to the other dosages and conventional concrete (without fiber). Microcracking due to internal stream pressure reduced the mechanical strengths of concrete at elevated temperatures. Also, from TGA it was observed that the amount of calcium carbonate in samples with fiber added, post carbonation was less than the mixes without fiber in it. Research limitations/implications: The present study has been limited to alkali resistant glass fibers as the conventional glass fibers undergo corrosion due to hydration. Practical implications: The glass fiber reinforced concrete can be used in the building renovation works, water and drainage works, b ridge and tunnel lining panels etc. Originality/value: Based upon the available literature, very seldom the studies are addressing the behaviour of alkali resistant glass fiber concrete and its exposure to elevated temperatures.

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Simplified analyses of stress induced anisotropy in remolded soft clay under undrained conditions

Lin P., Li Z.-x., Garg A., Yadav J. S.

Archives of Materials Science and Engineering

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2020

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Vol. 105, nr 2

56--64

EN

Purpose: The soil’s anisotropy induced by stress (i.e. stress induced anisotropy) has an important effect on the behavior of soil. This paper focuses on analyzing the anisotropy of remolded Shantou soft clay under compression stress path. Design/methodology/approach: Experiments were executed by using three axle experimental instruments. The data obtained from the plain strain tests were analyzed and the relationship between stress and strain was calculated by using the modified Duncan- Chang and Lade-Duncan models. The models were modified under the condition of plain strain and cohesion. Findings: It was concluded that in complex stress path conditions, the conventional triaxial tests may not fully reflect the actual stress of soil and its response in the Duncan-Chang and Lade-Duncan models. Research limitations/implications: The formulation of Mohr-Coulomb failure criterion in the plasticity framework is quite diffcult. As a result, dilatancy cannot be described. The properties of soil in unload or drained conditions remain to be part of further investigated. Practical implications: Based upon the two stiffness parameters, the modified Duncan- Chang model has captured the soil behaviour in a very conformable way and is recommened for practical modeling. These constitutive models of soil are widely used in the numerical analyses of soil structure such as embankments. Originality/value: Duncan-Chang and Lade-Duncan models widely used in engineering practices are modes based on conventional triaxial cases. Both models have have some inherent limitations to represent the stress-strain characteristics of soils, such as shear-induced dilatancy and stress path dependency and required corrections. In this investigation, the tests are carried out in undrained conditions. It is related to the properties of soil in load conditions.