Geogrid pullout load–strain behaviour and modelling using a transparent granular soil

Abstract

The paper describes the results of a series of geogrid pullout tests that were carried out in a novel large pullout box with a transparent granular soil. The test apparatus and methodology allows the entire geogrid specimen to be visible through the bottom of the box. Specimen displacements are computed from image analysis of pictures taken through the transparent bottom of the pullout box during each test. The geogrid material was an integral punched and drawn biaxial polypropylene geogrid. A series of reference tests were carried out on geogrid specimens 2000 mm long and loaded at a front clamp displacement of 1 mm/min. The results of these tests have been reported in previous publication by the writers. In the current study, this earlier database of test results and interpretation of results is extended to include tests with specimens of different (shorter) length and loaded at other displacement rates. The tensile loads in the specimens are estimated using two different nonlinear rate-dependent load–strain models with parameters determined independently from in-air tests. The predicted loads are compared to measured loads recorded at the front and end of specimens trimmed to short lengths. In addition, the paper compares the load–displacement response of an unmodified geogrid specimen to that of a nominal identical specimen with the transverse members removed. The load–strain models are used to deduce the component of total tensile load in the geogrid carried by the transverse geogrid members. Finally, test results for nominal identical specimens tested in air and in soil show that there is no detectable influence of soil confinement on longitudinal tensile stiffness of the geogrid product used in this study.

Triaxial Testing of Geosynthetics Reinforced Tailings with Different Reinforced Layers

“…In reinforcement engineering, the interface action characteristic of reinforced soil is the key technical index [5] that directly determines the stability of the reinforcement engineering. In 1974, Schlosser and Long first used triaxial tests to study the mechanical properties of reinforced sand.…”

Influence of Rib Stiffness and Limited Long-Term Junction Strength on Geogrid Performance

“…in the case of a rigid GGR. Theoretical considerations as well as carefully analyzed experiments have clearly shown that in the case of polymeric GGR this assumption is not valid (Sieira et al 2009;Ziegler and Timmers 2004;Bathurst and Ezzein 2016;Wilson-Fahmy et al 1994;Ezzein and Bathurst 2014). The displacement of the transverse ribs and thus the mobilization of the soil resistance is nonlinearly distributed over the length of the embedded GGR.…”

“…The extent to which friction and bearing resistance are mobilized along the GGR depends on how stiff the longitudinal ribs are and whether the junction can sustain the loading, Fig. 1, (Sieira et al 2009;Ziegler and Timmers 2004;Müller 2011;Jacobs et al 2014Jacobs et al , 2016Bathurst and Ezzein 2016). (In this paper the terms "flexible" and "stiff" or "rigid" refer to the stress-strain behavior of longitudinal ribs and not the flexural rigidity of the entire GGR).…”

“…Further, in the early 2000s, Ziegler and Timmers (2004) used a numerical discrete element model (DEM) to describe the interaction between the flexibility of the longitudinal ribs and local loading of the junctions. A similar approach was suggested by Bathurst and Ezzein (2016), Ezzein et al (2015). Based on the model of Ziegler and Timmers (2004), which is equivalent to the incremental load finite element model used by Wilson-Fahmy and Koerner (see Online Resource) (Wilson-Fahmy and Koerner 1993;Wilson-Fahmy et al 1994), the effects of the flexibility of the longitudinal ribs and the limited junction strength on the anchorage of a GGR were discussed by Müller (2011Müller ( , 2014.…”

Modelagem analítica de solos reforçados com geocélulas: aplicação na obtenção do fator de melhora do módulo (MIF) e do comportamento tensão/deformação da célula.

“…Com a evolução e o desenvolvimento da instrumentação, novos dados puderam ser coletados como as tensões normais e deformações, utilizando células de pressão (geralmente aplicadas abaixo da geocélula) e strain gauges (fixado em suas paredes) (DASH; RAJAGOPAL; KRISHNASWAMY, 2007;MENESES, 2004;ZHOU;WEN, 2008). Mais recentemente, o uso de solos transparentes (ISKANDER, 2010) vem sendo estudado para a análise de ensaios de carregamento em placa em solos reforçados com geossintéticos, incluindo geocélulas (BATHURST; EZZEIN, 2016;NELSEN, 2018;NELSEN;ZORNBERG, 2020;ZIEGLER;DERKSEN, 2019). 2019).…”