Showing papers by "Sanjay Kumar Shukla published in 2015"
TL;DR: In this article, a concrete mix of grade 40MPa was prepared in the laboratory with water-cement ratio of 0.5 and the concrete were cured for 1, 2, 3, 7, 14 and 28 days.
Abstract: Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength were tested. A controlled mix of concrete was also prepared in similar way using conventional materials and the results were compared with the tailings concrete. It was found that the iron ore tailings may be utilised for complete replacement for conventional aggregates in concrete. The iron ore tailings aggregates concrete exhibited a good mechanical strength and even in the case of compressive strength, there was an improvement of 11.56% over conventional aggregates concrete. The indirect tensile strength did ...
52 citations
TL;DR: In this article, the authors presented the details of the laboratory model strip footing load tests considering different relative densities of sand bed, focussing on the sand beds reinforced with a single layer of the woven geotextile reinforcement with wraparound ends.
Abstract: The experimental and numerical studies have continued to develop the cost-effective and convenient approach of using the geosynthetic reinforcement to increase the load-bearing capacity of shallow foundations. In the previous studies reported in the literature, the geosynthetic reinforcement has been used as a horizontal layer within the soil mass underlying the footings. This paper presents the details of the laboratory model strip footing load tests considering different relative densities of sand bed, focussing on the sand beds reinforced with a single layer of the woven geotextile reinforcement with wraparound ends. The experimental results of the study are compared with the numerical findings based on the finite-element analysis carried out using the software PLAXIS 2D (version 9.0). The results show that the proposed method of wrapping around the ends of the geosynthetic reinforcement brings three additional advantages: 1. increase in the ultimate load-bearing capacity, 2. significant increase in the stiffness of the sand bed in terms of its modulus of subgrade reaction, and 3. saving in the land space to construct a reinforced sand bed system. This study clearly demonstrates that by adopting the new practice of using the geosynthetic reinforcement with the wraparound ends in foundations, it is possible to support relatively heavier structures without allowing large settlements.
47 citations
TL;DR: In this paper, the results of an investigation into the interaction between the various electrical factors pertaining to resistivity tests in Perth sandy soil (specifically AC input voltage and frequency) and those controlling the soil characteristics, specifically water content and relative density of the soil, and the type of water employed in the tests, whether distilled or tap water.
Abstract: This paper presents the results of an investigation into the interaction between the various electrical factors pertaining to resistivity tests in Perth sandy soil (specifically AC input voltage and frequency) and those controlling the soil characteristics, specifically water content and relative density of the soil, and the type of water employed in the tests, whether distilled or tap water. The experimental apparatus was developed as per Australian standard AS 1289.4.4.1-1997 and was used for the electrical resistivity measurements. The test results indicate that the resistivity of the sandy soil is almost independent of both AC input voltage and frequency within the ranges used, while the choice of electrode material has an insignificant effect on the outcome of tests using this method. It was observed that the resistivity of sandy soil decreased rapidly with an increase in water content, but the rate of decrease reduced considerably for water contents over 12% in the case of distilled water and 10% fo...
24 citations
TL;DR: In this paper, a suction-controlled direct shear apparatus was modified to study the influence of matric suction on interface (a stainless steel plate), and the main modifications included the fabrication of the shear box base/test cell for interface testing, along with some other important features and modifications.
Abstract: The interfaces between saturated/unsaturated and structure are common to many offshore and on-shore civil engineering structures, but their behavior is not well understood. The shearing behavior of the interface plays a significant role in the stability and serviceability of the associated structures. With this in view, to study the influence of matric suction on interface (a stainless steel plate), a suction-controlled direct shear apparatus was modified. The main modifications included the fabrication of the shear box base/test cell for interface testing, along with some other important features and modifications that are described in this paper. By utilizing the modified direct shear apparatus, several suction-controlled direct shear tests were conducted on both the soil and the soil-steel plate interface. The main aim of this study was to develop laboratory testing equipment that can be used to determine shear strength of unsaturated soil-steel interfaces, at different shearing planes. The typical tes...
24 citations
TL;DR: In this article, the authors present the results of load tests conducted in the laboratory on an embedded model strip footing resting on a reinforced dense sand bed, where the reinforcement used was woven geotextile with wraparound ends.
Abstract: This paper presents the results of load tests conducted in the laboratory on an embedded model strip footing resting on a reinforced dense sand bed. The reinforcement used was woven geotextile with wraparound ends, as well as without wraparound ends for investigating the benefits of providing wraparounds. The number of reinforcement layers varied from 1 to 5. The ratio of embedment depth of the footing to its width, called the embedment depth ratio, varied from 0 to 1. The effect of utilizing the wraparound ends with the reinforcement on the load-bearing capacity of the reinforced sand bed has been of special interest in this study. The experimental results arising from the study are compared with the numerical findings based on the finite-element analysis (FEA) carried out using the PLAXIS 2D software. The study shows a significant improvement in both the load-bearing capacity and the stiffness of the sand bed with increasing number of reinforcement layers, as well as with the provision of wraparound end...
20 citations
TL;DR: In this article, the results of model square footing tests with vertical reinforcements inserted into the sand subgrade beyond the footing base only were presented, and the results were comparable particularly when the length of reinforcement and extent of reinforcement were two times the footing width.
Abstract: The restraining effects in the sand subgrade under the footing can be provided by inserting the vertical reinforcing bars beyond the footing base without disturbing the subgrade below the footing. This technique of soil reinforcement can be quite beneficial for the footings where improvement is necessary. This paper presents the results of model square footing tests with vertical reinforcements inserted into the sand subgrade beyond the footing base only. The variables selected for the investigation were spacing of vertical reinforcement, extent of reinforcement from the edge of footing, length of reinforcement, diameter of reinforcement, width of footing and surface characteristics of the reinforcement. The values of theoretical bearing capacity of reinforced sand subgrade were determined using the method of slices and compared with experimental results. It was found that results were comparable particularly when the length of reinforcement and extent of reinforcement were two times the footing width.
19 citations
TL;DR: In this paper, the authors present the effects of submergence on the settlement and bearing capacity of a surface strip footing resting on the reinforced sand bed at a relative density of 90% by conducting the laboratory model tests.
Abstract: This paper presents the effects of submergence on the settlement and the bearing capacity of a surface strip footing resting on the reinforced sand bed at a relative density of 90 % by conducting the laboratory model tests. The reinforcement layers used were woven geotextile layers, without and with wraparound ends. The number of reinforcement layers was varied from 1 to 4. The test tank had an arrangement for the water table rise, from the bottom of the sand bed constructed in the tank. The model strip footing was placed at the surface of the sand bed, and measurement of the settlement occurring with the rise of the water table, was taken to observe the effect of water table rise. When the water table reached the top surface of the sand bed, that is, the sand bed was fully submerged under water; the measurement of settlement of the footing was continued, by applying the load incrementally through the hydraulic jack. The results show that the rise of the water table causes a significant settlement of the footing for both unreinforced and reinforced cases. However, the beneficial effect of reinforcement layers was observed in terms of increased load-bearing capacity. An increase in the number of reinforcement layers, from 1 to 4 as well as providing the wraparound ends to the reinforcement, brought a significant increase in load-bearing capacity. When compared to the dry situation, there is a significant decrease in the load-bearing capacity as well as in the modulus of subgrade reaction of the unreinforced and reinforced sand beds with the rise of water table and full submergence.
16 citations
TL;DR: In this paper, an explicit analytical expression for the critical inclination of the failure plane within the soil backfill is also presented for torsion in rigid retaining walls, considering the most field parameters related to the wall geometry, soil backfills, and loadings, such as wall height, wall backfill face inclination, backfill slope angle, tension cracks, wall friction, wall-backfill adhesion, cohesion and angle of shearing resistance of backfill, surcharge, and both the horizontal and the vertical seismic loadings.
Abstract: In geotechnical engineering, there has been a need for the generalized analytical expression in explicit form for the dynamic (or seismic) active thrust from the c–φ (c = cohesion and φ = angle of shearing resistance) soil backfills on the rigid retaining walls since the early developments of explicit Rankine’s, Coulomb’s, and Mononobe–Okabe’s (M–O)’s analytical expressions. An attempt is made here to present a derivation of such an explicit generalized analytical expression based on the pseudo-static approach, considering the most field parameters related to the wall geometry, soil backfill, and loadings, such as wall height, wall-backfill face inclination, backfill slope angle, tension cracks, wall friction, wall-backfill adhesion, cohesion and angle of shearing resistance of backfill, surcharge, and both the horizontal and the vertical seismic loadings. The development of an explicit analytical expression for the critical inclination of the failure plane within the soil backfill is also presented for t...
13 citations
TL;DR: In this paper, an experimental set-up is developed based on the Wenner Array, and has been used for determining the electrical resistivity of the tailings at different relative densities in dry and fully saturated conditions.
Abstract: This paper presents the details of an experimental study on the electrical resistivity of iron ore mine tailings produced in Western Australia. In the study, an experimental set-up is developed based on the Wenner Array, and has been used for determining the electrical resistivity of the tailings at different relative densities in dry and fully saturated conditions. The apparent electrical resistivity of the iron ore mine tailings ranged from 11 kΩm for a very dense state to 19 kΩm for a very loose state in dry condition; while for the fully saturated condition, the resistivity ranged from 20 to 31 Ωm for very dense state to very loose state, respectively. The results are discussed for their practical applications such as identifying weak zones in tailing embankments, extent of corrosion in buried steel pipelines, and extent of degree of compaction in structural fills.
13 citations
TL;DR: In this paper, the seismic stability of a reinforced soil wall has been analyzed using the horizontal slice method considering the pseudo-static seismic forces, and the effect of various parameters including wall inclination angle, angle of internal friction of soil, horizontal seismic loading, cohesion of the backfill and surcharge loading has been examined.
Abstract: The seismic stability of a reinforced soil wall has been analyzed using the horizontal slice method considering the pseudo-static seismic forces. The effect of various parameters including wall inclination angle, angle of internal friction of soil, horizontal seismic loading, cohesion of the backfill and surcharge loading has been examined. It is found that the stability of a reinforced soil wall is largely affected by the horizontal seismic forces. The tensile resistance which has to be mobilized by the reinforcement to maintain the stability of wall, increases with an increase in surcharge, horizontal seismic forces, whereas the same decreases with an increase in the cohesion of soil. The normalized geosynthetic tensile reinforcement force is used for comparing the effect of different parameters.
12 citations
TL;DR: In this article, a semi-analytical solution of MPNE transport equations with linear and exponential distance-dependent dispersivity is developed, which can be used for simulation of observed data of reactive plume through the porous media at field scale and also for the remediation of contaminated subsurface soil.
Abstract: In this paper, a semi-analytical solution of multiprocess non-equilibrium (MPNE) transport equations with linear and exponential distance-dependent dispersivity is developed. The model has been used to simulate the laboratory experimental data of chloride and fluoride solutes through a 15 m long heterogeneous soil column. It is observed that a better fit to the observed breakthrough curves is obtained, when the mass transfer between advective and non-advection region is considered. It is also observed that both linear and exponential distance-dependent dispersion models give a good fit to the observed breakthrough curves, however, the exponential distance-dependent dispersion model gives a much better fit. The estimated transport parameters can be used for simulation of observed data of reactive plume through the porous media at field scale and also for the remediation of contaminated subsurface soil.
TL;DR: A simple analytical model verified with experimental data for estimating the void ratio of fibre-reinforced soils is developed which can be used to express the compressibility of fibre reinforced soils in geotechnical engineering applications as mentioned in this paper.
Abstract: This technical note extends the concept of void ratio, presented traditionally in soil mechanics, for fibre-reinforced soils. Phase relationships related to the void ratio of fibre-reinforced soils are presented along with their definitions. A simple analytical model verified with experimental data for estimating the void ratio of fibre-reinforced soils is developed which can be used to express the compressibility of fibre-reinforced soils in geotechnical engineering applications. The results indicate that the void ratio of fibre-reinforced soils is dependent on the volume ratio of fibre-soil solid.