Investigation of factors influencing behavior of single geocell-reinforced bases under static loading
ABSTRACT Geocell, one type of geosynthetics manufactured in the form of three-dimensional interconnected cells, can be used as a reinforcement to improve the behavior of base courses by providing lateral confinement to increase their stiffness and strength and reduce surface permanent-deformation. However, the use of geocells for base reinforcement is hindered by the existing gap between applications and theories. This study experimentally investigated the factors influencing the behavior (stiffness and bearing capacity) of single geocell-reinforced bases including shape, type, embedment, height of geocells, and quality of infill materials. Three of the four types of geocells investigated in this study were made of novel polymeric alloys using a new manufacturing technology. Repeatability and potential scale effects on test results were examined. The test results showed that the geocell placed in a circular shape had a higher stiffness and bearing capacity than that placed in an elliptical shape. The performance of the geocell-reinforced base depended on the elastic modulus of the geocell sheet. The unconfined geocell had a lower stiffness but a higher ultimate load capacity than the confined geocell. The benefit of the geocell was minimized when the infill material, quarry waste with apparent cohesion, was used as compared with the Kansas River sand without apparent cohesion. The single geocell-reinforced base had a lower stiffness and bearing capacity than the multiple geocell-reinforced base.
- SourceAvailable from: Amarnath Hegde
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- "Geocells can offer faster, cheaper, sustainable, and environmentally friendly solutions to many complex geotechnical problems. Many researchers in the past have demonstrated the beneficial aspects of geocells with the help of experimental and field studies (Sireesh et al., 2009; Tafreshi and Dawson, 2010; Pokharel et al., 2010; Lambert et al., 2011; Yang et al., 2012; Thakur et al., 2012; Tafreshi and Dawson, 2012; Tavakoli Mehrjardi et al., 2012; Tafreshi et al., 2013; Biswas et al., 2013; Sitharam and Hegde, 2013; Tanyu et al., 2013; Dash and Bora, 2013; Leshchinsky and Ling, 2013a; Tafreshi et al., 2014; Hegde and Sitharam, 2014a; Indraratna et al., 2014). However, one cannot always depend on the experimental and field studies for the design and analysis of the complex geotechnical problems. "
ABSTRACT: Numerical modelling of the geocell has been always a big challenge due to its complex honeycomb structure. Generally, the equivalent composite approach is adopted to model the geocells. In equivalent composite approach, the geocell-soil composite is treated as the soil layer with improved strength and stiffness values. Though this approach is very simple, it is unrealistic to model geocells as the soil layer. This paper presents a more realistic modelling approach to model geocells in 3-dimensional (3D) framework. Numerical simulations have been carried by forming the actual 3D honeycomb shape of the geocells using the finite difference package FLAC3D (Fast Lagrangian Analysis of Continua in 3D). Geocells are modelled using the geogrid structural element available in the FLAC3D with the inclusion of the interface element. In addition to the modelling of geocells, other two cases, namely, only geogrid and geocell with additional basal geogrid cases were also modelled. It was found that the geocells distribute the load laterally and to a relatively shallow depth as compared to unreinforced case and the geogrid reinforced case. The numerical model was also validated with the experimental studies and the results are found to be in good agreement with each other. The validated numerical model was used to study the influence of various properties of the geocells on the performance of the reinforced foundation beds. The performance of the foundation bed was directly influenced by the modulus and the height of the geocells. Similarly, the pocket size of the geocell inversely affected the performance of the reinforced beds. The geocell with textured surface yielded better performance than the geocell with smooth surface.Geotextiles and Geomembranes 12/2014; 43(2). DOI:10.1016/j.geotexmem.2014.11.009 · 2.38 Impact Factor
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- "construction of footings over soft soil, stable embankments , slope and earth stabilization, road construction layers, and pavement system (e.g. Hufenus et al., 2006; Dash et al., 2007; Bathurst et al., 2009; Madhavi Latha and Somwanshi, 2009; Zhang et al., 2010; Pokharel et al., 2010; Moghaddas Tafreshi and Dawson, 2012; Boushehrian et al., 2011; Lambert et al., 2011; Koerner, 2012. Yang et al., 2012; Thakur et al., 2012; Tavakoli Mehrjardi et al., 2012; Leshchinsky and Ling, 2013; Tanyu et al., 2013; Chen et al., 2013). "
ABSTRACT: Sandy soil/aggregate, such as might be required in a pavement foundation over a soft area, was treated by the addition of one or more geocell layers and granulated rubber. It was then subjected to cyclic loading by a 300 mm diameter plate simulative of vehicle passes. After an initial study (that established both the optimum depth of the uppermost geocell layer and of the geocell inter-layer spacing should be 0.2 times plate diameter), repeated loading was applied to installations in which the number of geocell layers and the presence or absence of shredded rubber layers in the backfill was changed. The results of the testing reveal the ability of the composite geocell-rubber-soil systems to ‘shakedown’ to a fully resilient behavior after a period of plastic deformation except when there is little or no reinforcement and the applied repeated stresses are large. When shakedown response is observed, then both the accumulated plastic deformation prior to a steady-state response being obtained and the resilient deformations thereafter are reduced. Efficiency of reinforcement is shown to decrease with number of reinforcement layers for all applied stress levels and number of cycles of applied loading. The use of granulated rubber layers are shown to reduce the plastic deformations and to increase the resilient displacements compared to the comparable non-rubber construction. By optimal use of geocells and granulated rubber, deformations can be reduced by 60–70% compared with the unreinforced case while stresses in the foundation soil are spread much more effectively. On the basis of the study, the concept of combining several geocell layers with shredded rubber reinforcement is recommended for larger scale trials and for economic study.Geotextiles and Geomembranes 02/2014; 42(1):25–38. DOI:10.1016/j.geotexmem.2013.12.003 · 2.38 Impact Factor
- "The interconnected cells in the geocell form a slab that behaves like a large pad that spreads the applied load over a wider area (Thakur et al, 2012a). Many researchers have highlighted the advantages of using geocells in construction activities in geotechnical engineering through their studies (Pokharel et al., 2010; Lambert et al., 2011; Yang et al., 2012; Thakur et al., 2012b; Mehdipour et al., 2013; Sitharam and Hegde, 2013). Tavakoli Mehrjardi et al. (2012) used the combination of geocell reinforcement and rubber soil mixture to protect buried PVC pipes. "