Long-term pull-out tests on polymergrids in sand

Kutara, Katsuyuki; Aoyama, Noriaki; Yasunaga, Hiroyuki; Kato, Toshihiro

doi:10.1016/0148-9062(90)95187-6

Cited by 3 publications

(1 citation statement)

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“…Displacement-controlled tests are typically performed at a constant rate of displacement (Juran and Chen 1988;Palmeira and Milligan 1989;Berg and Swan 1991;Farrag et al 1993;Fannin and Raju 1993), at rates of displacement between 0.1 and 20 mm/min, with relatively slow rates of about 1 mm/min being preferred. Load-controlled tests are reported for conditions of constant load (Kutara et al 1988;Collin and Berg 1993), a constant rate of loading, cyclic loading (Yasuda et al 1992), or a slow repeated loading (Hanna and Touhamia 1991). Based on their cyclic and monotonic pullout test data, Yasuda et al (1992) make the general observation that (i) the maximum pullout resistance under monotonic or cyclic loading is affected by soil type and overburden pressure, (ii) the maximum pullout resistance in cyclic loading is greater than that observed in monotonic loading, and (iii) the maximum pullout resistance under a cyclic overburden pressure decreases with an increase of the amplitude of the cyclic pressure.…”

Section: Introductionmentioning

confidence: 98%

Load-strain-displacement response of geosynthetics in monotonic and cyclic pullout

Raju¹,

Fannin²

1998

Can. Geotech. J.

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Mobilization of the pullout resistance of geosynthetics in monotonic and cyclic modes is described from both displacement-and load-controlled tests performed at normal stresses in the range 4-17 kPa. The tests were performed on three geogrids and two geomembranes embedded nearly 1.0 m in a uniformly graded sand. Results for load-controlled tests at a constant rate of 0.25 kN/(m⋅min -1 ), followed by several series of load cycles of increasing amplitude, are compared with displacement-controlled tests at a constant rate of 0.5 mm/min. In general the geogrids behave as an equivalent textured sheet. Pullout behaviour, and especially the incremental displacement mobilized at cyclic loads close to the maximum resistance, is found to vary with type of geogrid. In only one case was cyclic pullout resistance of a grid found to exceed the monotonic resistance. A comparison of the cyclic and monotonic response yields a constant ratio of pullout resistance at large displacement, but one which is not unique to a particular specimen. Cyclic strains of decreasing amplitude are mobilized along a test specimen, with most of the necessary relative displacement occurring close to the loaded end and the embedded end showing little response.Résumé : La mobilisation de la résistance à l'arrachement des géosynthétiques en sollicitation monotonique et cyclique est décrite ici à partir d'essais à déplacement ou à charge contrôlés, à des niveaux de contrainte normale compris entre 4 et 17 kPa. Les essais ont été effectués sur trois géogrilles et deux géomembranes enfouies sous près de 1,0 m de sable à granulométrie uniforme. Les résultats d'essais à chargement controlé à un taux de 0,25 kN/(m⋅min -1 ) suivis de plusieurs séries de chargement cyclique d'amplitude croissante ont été comparés avec les résultats d'essais à déplacement contrôlé menés à une vitesse constante de 0,5 mm/min. De façon générale, les géogrilles se comportent comme une feuille texturée équivalente. Le comportement à l'arrachement dépend du type de géogrille de même que le déplacement incrémental mobilisé pour des chargements cycliques proches de la résistance maximale. Dans un seul cas on a trouvé que la résistance à l'arrachement cyclique d'une géogrille pouvait dépasser la résistance monotonique. La comparaison des réponses cycliques et monotoniques indique un rapport de résistance à l'arrachement constant pour les grands déplacements. Ce rapport n'est cependant pas unique pour un spécimen donné. Des déformations cycliques d'amplitude décroissante sont mobilisées le long du spécimen et le déplacement relatif nécessaire prend place près de l'extrémité où la charge est appliquée, l'autre extémité montrant peu de réponse.

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Section: Introductionmentioning

confidence: 98%

Load-strain-displacement response of geosynthetics in monotonic and cyclic pullout

Raju¹,

Fannin²

1998

Can. Geotech. J.

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Effects of Sustained and Repeated Tensile Loads on Geogrid Embedded in Sand

Pincus¹,

Min²,

Leshchinsky³

et al. 1995

Geotechnical Testing Journal

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Design methods for reinforced soil structures under static loading conditions are relatively well established. Little research has been conducted on the behavior of embedded geosynthetics subjected to repeated loadings. Such research is needed to improve the design of reinforced soil structures subjected to traffic and seismic loadings. The study reported here is related to the long-term performance of a geogrid embedded in Ottawa sand under several confining pressures and subjected to various tensile loads. Different magnitudes of sustained and repeated tensile loads were applied to the geogrid incrementally using a pullout device. The confining pressure increased the soil-geogrid interface friction force and thus affected strain distribution along the geogrid length. Creep developed in the geogrid as the applied tensile load increased. The geogrid creep strain rate at a given tension force was found to be independent of confining pressure at the point of this force application, that is, creep can be viewed as an intrinsic property of the geogrid. A rapid pullout failure of geogrid occurred as the applied sustained load approached the ultimate pullout capacity. Conversely, under repeated loading the pullout occurred progressively. The ultimate pullout load and interaction coefficient, Ci, obtained from repeated loading tests were about 20% less than the values obtained from sustained loading tests. This suggests that a Ci smaller than that obtained in static (conventional) tests should be used in structures subjected to dynamic load. Creep under repeated load was smaller than that under sustained load.

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