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Bhattacharjee A.,Jorhat Engineering College | Mittal S.,Indian Institute of Technology Roorkee | Krishna A.M.,Indian Institute of Technology Guwahati
International Journal of Geotechnical Engineering | Year: 2011

Micropiles are have been effectively used in many ground improvement applications to increase the bearing capacity and reduce settlement, particularly in strengthening existing foundations. This paper presents the results of laboratory model tests on the behavior of a square footing supported on micropiles. The parameters varied in the study include micropile diameter, length, spacing between the micropiles and distance of micropile from the edge of the footing. Bearing capacity of unreinforced and reinforced footings is determined and bearing capacity improvement factor and settlement reduction factors are evaluated. The results are then analyzed to study the effect of each parameter. The improvement of bearing capacity is noticed when the diameter and length of micropile increases and spacing between the micropiles and distance of micropile from edge of footing decreases. J. Ross Publishing, Inc. © 2011

Bhattacharjee A.,Jorhat Engineering College | Murali Krishna A.,Indian Institute of Technology Guwahati
14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering | Year: 2011

This paper presents the simulation of wrap faced reinforced soil retaining walls subjected to seismic shaking using FLAC 3D. FLAC 3D is a three dimensional explicit finite difference programme used for engineering mechanics problems. The backfill soil of reinforced soil wall is modeled as elasto-plastic material. Duncun hyperbolic models are considered as constitutive model for backfill soil. The reinforcement is modeled as geogrid shell structural element. The interfaces are used between the reinforcement and shell for proper interaction. The steps followed in numerical simulations are similar to that of physical model tests reported in literature. The results obtained from numerical model are compared with the experimental results reported in the literature. The effect of parameters like reinforcement stiffness, reinforcement length, number of layers of reinforcement, length of wrap faced reinforced soil wall and frequency of excitation on model behavior are observed and quantified.

Bhattacharjee A.,Jorhat Engineering College | Krishna A.M.,Indian Institute of Technology Guwahati
Indian Geotechnical Journal | Year: 2015

Behavior of reinforced soil structure depends mainly on strain mobilization within reinforcement and its surrounding soil. This paper presents the soil and reinforcement strains developed within wrap faced reinforced soil wall subjected to dynamic excitation and their inter-dependence on formation of deformation zones. Octahedral shear strains developed on backfill soil and axial strains in reinforcement during the dynamic excitation are determined from the numerical simulations and analyzed. In general, the octahedral strain increments during the dynamic excitation are more at higher elevations near the end of reinforcement and the reinforcement strain increments are lower at top layers. Parametric studies are also conducted to study behavior of soil strain and reinforcement strain for different reinforcement configurations and backfill materials. The octahedral shear strain increments and reinforcement strain increments are influenced by the longer reinforcement layers, more number of reinforcement layer and higher backfill friction angle. It is observed that at the lower elevations the soil strains and reinforcement strains were not significantly affected by change in reinforcement length. So providing longer reinforcements up to 1/3–1/2 the height of wall would yield better performance results. © 2014, Indian Geotechnical Society.

Hatibaruah D.,Jorhat Engineering College | Baruah D.C.,Tezpur University | Sanyal S.,Tocklai Experimental Station
Journal of Food Processing and Preservation | Year: 2013

Microwave drying characteristics of Assam crush, tear, curl (CTC) tea were determined at five different microwave power of 180, 360, 540, 720 and 900W respectively. The effect of power level on moisture content and drying rate (d.b.) of 50g CTC tea sample were investigated. The time required to reduce the moisture content to any given level in microwave drying was dependent on the power level. Four mathematical models (Henderson and Pabis, Lewis, Page and logarithmic) were used for fitting experimental data. The estimated empirical parameters together with the corresponding sum of square error from nonlinear regression analysis for all the models were tested. The Page model was found to have the better suitability for describing drying characteristics of Assam CTC tea. © 2012 Wiley Periodicals, Inc.

Bhattacharjee A.,Jorhat Engineering College | Murali Krishna A.,Indian Institute of Technology Guwahati
International Journal of Geotechnical Earthquake Engineering | Year: 2012

Reinforced soil walls offer excellent solution to problems associated with earth retaining structures under seismic conditions. Among different types of reinforced soil walls, rigid faced walls are widely used in various infrastructure projects. Presented is the seismic response of such rigid faced reinforced soil retaining walls through numerical models. Development of numerical model for simulating the shaking table tests on rigid faced reinforced soil retaining walls and its application in investigating the seismic response of wall models are presented. These models are discussed in depth in the article. The results obtained from the numerical simulations are validated with that of experimental studies reported in the literature. Sensitivity analyses are conducted to understand the affect of different material properties like backfill friction angle, backfill dilation angle and stiffness of reinforcement on model response. Copyright © 2012, IGI Global.

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