Bearing capacity of strip foundations reinforced with geogrid sheets by using upper bound finite‐element limit analysis

Abstract

SUMMARY By using the upper bound finite‐elements limit analysis, with an inclusion of single and two horizontal layers of reinforcements, the ultimate bearing capacity has been computed for a rigid strip footing placed over (i) fully granular, (ii) cohesive‐frictional, and (iii) fully cohesive soils. It is assumed that (i) the reinforcements are structurally strong so that no axial tension failure can occur, (ii) the reinforcement sheets have negligible resistance to bending, and (iii) the shear failure can take place between the reinforcement and soil mass. It is expected that the different approximations on which the analysis has been based would generally remain applicable for reinforcements in the form of geogrid sheets. A method has been proposed to incorporate the effect of the reinforcement in the analysis. The efficiency factors, ηc and ηγ, to be multiplied with Nc and Nγ , for finding the bearing capacity of reinforced foundations, have been established. The results have been obtained (i) for different values of ϕ in case of fully granular and cohesive‐frictional soils, and (ii) for different rates at which the cohesion increases with depth for a fully cohesive soil. The optimum positions of the reinforcements' layers have also been determined. The effect of the reinforcements' length on the results has also been analyzed. As compared to cohesive soils, the granular soils, especially with higher values of ϕ, cause a much greater increase in the bearing capacity. The results compare reasonably well with the available theoretical and experimental data from literature. Copyright © 2013 John Wiley & Sons, Ltd.

Bearing capacity of circular foundations reinforced with geogrid sheets

“…Note that the bearing capacity factors and corresponding efficiency factors have been obtained by considering that the principle of superposition remains applicable. Since the principle of superposition results in a conservative estimate, the failure load thus obtained will always be safe (Davis and Booker, 1971;Bolton and Lau, 1993;Kumar and Sahoo, 2013). For computing η c , the value of γ has been kept equal to zero, on the other hand, for determining η γ , the value of c is kept equal to zero.…”

“…The usage of the reinforcements in a soil medium became especially popular after the pioneering work of Vidal (1966). Subsequently, for assessing the effect of the reinforcements on load carrying capacity and settlement of the foundations, a number of researchers have performed extensive studies by using a series of models tests (Binquet and Lee, 1975;Fragaszy and Lawton, 1984;Guido et al, 1986;Khing et al, 1993;Omar et al, 1993;Das and Omar, 1994;Adams and Collin, 1997;Abu-Farsakh et al, 2013) and different computational approaches (Asaoka et al, 1994;Otani et al, 1998;Yu and Sloan, 1997;Huang and Hong, 2000;Blatz and Bathurst, 2003;Michalowski, 2004;Deb et al, 2007;Chakraborty and Kumar, 2012;Miyata and Bathurst, 2012;Asakereh et al, 2013;Kumar and Sahoo, 2013). These studies are generally meant for reinforced strip foundations.…”

“…In the present research, the bearing capacity of a circular foundation embedded with single and two horizontal layers of the reinforcements in the form of circular geogrid sheets, has been determined by using the upper bound finite elements limit analysis in combination with linear optimization. The upper bound formulation, to incorporate the inclusion of the reinforcement sheets in the analysis, has been implemented from the work of Kumar and Sahoo (2013) for strip foundations on the basis of finite elements and linear optimization. Similar to the study of Kumar and Sahoo (2013), the circular reinforcement sheets in the present analysis are assumed to be structurally strong to resist axial tension but these reinforcements are assumed not to have any resistance to bending.…”

“…The upper bound formulation, to incorporate the inclusion of the reinforcement sheets in the analysis, has been implemented from the work of Kumar and Sahoo (2013) for strip foundations on the basis of finite elements and linear optimization. Similar to the study of Kumar and Sahoo (2013), the circular reinforcement sheets in the present analysis are assumed to be structurally strong to resist axial tension but these reinforcements are assumed not to have any resistance to bending. The critical depths of the reinforcement layers, both for single and two layers of reinforcement sheets have been computed for different cases.…”

Stability analysis of homogenized stone column reinforced foundations using a numerical yield design approach

“…Among these techniques, the case of "thin" linear inclusions, such as for example metal strips or geotextiles in the earth reinforcement technique or soil nailing, may be directly carried out with finite elements adapted to limit analysis. For such reinforcement techniques, the inclusions are modeled as linear structured elements [13][14][15][16].…”