Single Layer Of Reinforcement Research Articles

An Experimental Study into Behaviour of Circular Footing on Reinforced Soil

The experimental investigations are reported on the study of load-deformation behavior of a model circular footing on reinforced soil in respect of two-layered system comprising clay as sub-grade and mine waste as backfill material. The footing was subjected to axial load. Two different types of reinforcing materials such as Kolon Geo-grid (KGR-40) and rubber grids derived out of waste tyres were used in the study. The study revealed appreciable increase in ultimate bearing pressure and decrease in settlement with the provision of a single layer reinforcement. Further, rubber grid performed better than the Geo-grid in respect to BCR and SRF. The study indicates significance of solid waste materials such as mine wastes and discarded tyres as effective civil engineering construction materials.

A parametric study of stability of geotextile-reinforced soil above an underground cavity

A study based on two-dimensional finite element analyses under plane strain condition was performed by PLAXIS code to investigate the behavior of geotextile-reinforced soil above an underground cavity. The effects of depth of single layer, tensile stiffness, number and length of reinforcement layers, and size of cavity on settlement of ground surface and head of cavity have been investigated. Results indicated that when a single layer of reinforcement is used, there is a critical depth at which settlements are maximum. Maximum settlements reduce with increase in stiffness of reinforcement. Also settlements reduce with increase in number and length of reinforcement but there is a critical value for number and length of geotextile which increase more than this certain value has not significant effect on reduction of settlements. Also for a given load and tensile stiffness, increase in length of reinforcement has more effect for higher diameter of cavity.

Mechanical response of steel wire wound reinforced rubber flexible pipe under internal pressure

Steel wire wound reinforced flexible pipe in this study mainly consists of multiple anisotropic steel wire wound reinforcement layers and multiple isotropic rubber layers. Based on 3D anisotropic elastic theory, the analytic solutions of stresses and elastic deformations of steel wire wound reinforced rubber flexible pipe under internal pressure are presented. As the adjacent reinforcement layers with wound angle have different radii, the single reinforcement layer shows the effect of tensile-shear coupling. Moreover, the static loading test results of steel wire wound reinforced rubber flexible pipe under internal pressure are basically coincided with the calculated values by present method.

Experimental Study of Bearing Capacity of Granular Soils, Reinforced with Innovative Grid-Anchor System

The pull-out resistance of reinforcing elements is one of the most significant factors in increasing the bearing capacity of geosynthetic reinforced soils. In this research a new reinforcing element that includes elements (anchors) attached to ordinary geogrid for increasing the pull-out resistance of reinforcements is introduced. Reinforcement therefore consists of geogrid and anchors with cubic elements that attached to the geogrid, named (by the authors) Grid-Anchor. A total of 45 load tests were performed to investigate the bearing capacity of square footing on sand reinforced with this system. The effect of depth of the first reinforcement layer, the vertical spacing, the number and width of reinforcement layers, the distance that anchors are effective, effect of relative density, low strain stiffness and stiffness after local shear were investigated. Laboratory tests showed that when a single layer of reinforcement is used there is an optimum reinforcement embedment depth for which the bearing capacity is the greatest. There also appeared to be an optimum vertical spacing of reinforcing layers for multi-layer reinforced sand. The bearing capacity was also found to increase with increasing number of reinforcement layer, if the reinforcement were placed within a range of effective depth. The effect of soil density also is investigated. Finally the results were compared with the bearing capacity of footings on non-reinforced sand and sand reinforced with ordinary geogrid and the advantages of the Grid-Anchor were highlighted. Test results indicated that the use of Grid-Anchor to reinforce the sand increased the ultimate bearing capacity of shallow square footing by a factor of 3.0 and 1.8 times compared to that for un-reinforced soil and soil reinforced with ordinary geogrid, respectively.

Response of multilayer geosynthetic-reinforced bed resting on soft soil with stone columns

In the present study, a mechanical model has been developed to study the behavior of multilayer geosynthetic-reinforced granular fill over stone column-reinforced soft soil. The granular fill and geosynthetic reinforcement layers have been idealized by Pasternak shear layer and rough elastic membranes, respectively. The Kelvin–Voight model has been used to represent the time-dependent behavior of saturated soft soil. The stone columns are idealized by stiffer springs and assumed to be linearly elastic. The nonlinear behavior of the soft soil and granular fill is considered. The effect of consolidation of soft soil due to inclusion of the stone columns on settlement response has also been included in the model. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution and results are presented in nondimensional form. It has been observed that if the soft soil is improved with stone columns, the multilayer reinforcement system is less effective as compared to single layer reinforcement to reduce the total settlement as there is considerable reduction in the total settlement due to stone column itself. Multilayer reinforcement system is effective for reducing the total settlement when stone columns are not used. However, multilayer reinforcement system is effective to transfer the stress from soil to stone column. The differential settlement is also slightly reduced due to application of multiple geosynthetic layers as compared to the single layer reinforcement system.

Load-Settlement Analysis of Geosynthetic-Reinforced Soil with a Simplified Model

Using a simplified model, the load-settlement behaviour of a geosynthetic-reinforced soil is for mulated. The model and formulation are flexible to accommodate inhomogeneity of the medium and multiple reinforcement layers with no or very little extra computational effort. The developed formulation is verified by using the finite element method and is confirmed to be efficient and convenient for computation. Compared with the previous simplified soil model, the present model can be defined uniquely by soil material properties alone and has an adequate mechanism to reproduce the behaviour of a continuous medium including the shear load transfer. A previous simplified model was found to be inadequate for deep soft soil. Also, it was found that at relatively large load levels, multiple reinforcement layers are as effective as a combination of a single reinforcement layer and gravel layer in reducing the settlement.

Experimental and numerical investigation of the bearing capacity of model circular and ring footings on reinforced sand

A study was performed to investigate the bearing capacity of circular and ring footings on reinforced sand by conducting laboratory model tests along with numerical analysis. The effects of the depth of the first layer of reinforcement, vertical spacing and number of reinforcement layers on bearing capacity of the footings were investigated. Both the experimental and numerical studies indicated that, when a single layer of reinforcement is used there is an optimum reinforcement embedment depth for which the bearing capacity is greatest. There also appeared to be an optimum vertical spacing of reinforcing layers for multi-layer reinforced sand. The bearing capacity was also found to increase with increasing number of reinforcement layers, if the reinforcements were placed within a range of effective depths. In addition, the analysis indicated that increasing reinforcement stiffness beyond a threshold value does not result in a further increase in the bearing capacity.

Carbon-fibre-reinforced plastic (CFRP) strengthening of aluminium extrusions

The flexural behaviour of compound beams in which unidirectional carbon-fibre-reinforced plastic (CFRP) is externally bonded to extruded aluminium box-sections, is discussed. Simple transformed-section analysis and elastic buckling theory have been adapted to predict improvements in stiffness and strength with single-layer reinforcement. Close correlation between theory and experiment is observed and maximum gains in stiffness and ultimate strengths of 75% and 63%, respectively, are demonstrated with only a 7% weight increase. It is shown that the effects of the adhesive can be neglected when predicting the performance of the hybrid beam. Shape optimisation has been successfully applied to illustrate the potential of this technique for ‘new-build’ applications. Initial findings have produced weight savings of 33% in comparison to an all-aluminium optimised box-section.

Reinforced granular fill-soft soil system: confinement effect

A new mathematical model has been developed for the analysis of a reinforced foundation bed by incorporating the confinement effect of a single layer of reinforcement. It is quantified in terms of the average increase in confining pressure due to the reinforcement from which modified shear stiffnesses of the granular soil surrounding the reinforcement are obtained. Parametric studies for plane strain conditions show that the confinement effect of reinforcement leads to an improved mechanical response over the unreinforced granular fill-soft soil foundation system.

Reinforced granular fill-soft soil system: Membrane effect

A new model for a reinforced shallow foundation bed is proposed by incorporating the ‘rough membrane’ element for a single layer reinforcement. Mechanics of the rough membrane element with the assumption of horizontal shear stress transfer at the soil/reinforcement interfaces are explained and formulated. The model is generalized by incorporating nonlinear responses of the soft soil and of the granular fill under plane strain loading conditions. The membrane effect is quantified in terms of the improvement in the load-settlement responses of the composite foundation system over the unreinforced one. Parametric results indicate that reinforcement while in tension spreads the load over a larger area, leading to a reduction in the settlement beneath the footing.