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Efeito da danificação durante a instalação em obra de geogrelhas no seu comportamento ao arranque

Publication . Paula, António Miguel; Pinho-Lopes, Margarida; Lopes, Maria de Lurdes

Alguns geossintéticos foram submetidos aos procedimentos de instalação em obra através da construção de aterros experimentais. Os efeitos da danificação induzida no comportamento mecânico de curto prazo foram avaliados recorrendo a ensaios de tracção de geossintéticos. Foi promovida uma campanha de ensaios de arranque de geossintéticos, realizados numa caixa de grandes dimensões e de acordo com a norma europeia EN 13738. A campanha de ensaios incluiu duas geogrelhas extrudidas biaxiais em polipropileno com diferentes valores da resistência nominal. Com esta selecção de materiais procurou-se avaliar a influência da sua resistência nominal no efeito da DDI no comportamento ao arranque da interface solo-geossintético. Os resultados dos ensaios realizados são apresentados e discutidos.

2010Conference object

Open access

Long-term response and design of two geosynthetics: effect of field installation damage

Publication . Pinho-Lopes, Margarida; Paula, António Miguel; Lopes, Maria de Lurdes

This paper contributes to understanding how installation damage of geosynthetics influences their long-term response and design. A geotextile and a geogrid were exhumed after installation under real conditions; their long-term tensile behaviour was investigated using conventional creep and creep rupture tests. Reduction factors for installation damage, creep and their combined effect were computed. The main aim of the paper was to assess how the long-term response of the geosynthetics was influenced by installation damage and whether it would be necessary to update current design approaches. The installation damage affected the mechanical response of both geosynthetics; important strength reductions were observed, particularly for the most severe installation conditions. The results indicate that, contrary to what has been reported in the literature, the creep rupture response of the geotextile changed after installation damage. When tested under similar creep loads (fraction of the sample tensile strength), both geosynthetics exhibited reduced potential for creep rupture and smaller strains at the end of primary creep. Changes in stiffness were less important than those for strength, for both short- and long-term response. There was synergy between installation damage and creep; the traditional approach to design was unsafe for the geotextile and slightly conservative for the geogrid.

2018Journal article

Restricted access

Soil–geosynthetic interaction in pullout and inclined-plane shear for two geosynthetics exhumed after installation damage

Publication . Pinho-Lopes, Margarida; Paula, António Miguel; Lopes, Maria de Lurdes

This paper contributes to a better understanding of how installation damage of geosynthetics can affect soil–geosynthetic interaction during pullout and inclined-plane shear. The effects of installation damage induced in field trials of a woven geotextile and a woven geogrid were studied. The results indicated that after installation the accumulation of a layer of fine particles over the geosynthetic can reduce the skin friction available, particularly for sheet materials. Installation damage can induce premature tensile failure in pullout tests, along the unconfined portion of the geosynthetic, causing a significant reduction in the corresponding coefficient of interaction. The contribution of the bearing members to the coefficient of interaction during pullout was estimated using equations from the literature. Such estimates were too optimistic. The installation damage induced had little influence on the soil–geosynthetic coefficient of interaction in the inclined plane shear test. The different relative movements of the soil and geosynthetic in pullout and inclined-plane shear, as well as the deformation of the reinforcements during pullout, enabled different mobilisation of the interface strength. For the comparable conditions tested, the coefficient of interaction from inclined plane shear tests was larger than that measured from pullout tests. The reduction factor for installation damage obtained from tensile tests overestimated the effects of the installation conditions on the soil–geosynthetic interface from both pullout and inclined plane shear tests.

2016Journal article

Restricted access

Effect of damage during installation on the mechanical behaviour of a biaxial woven polyester geogrid

Publication . Paula, António Miguel; Pinho-Lopes, Margarida; Lopes, Maria de Lurdes

This paper reports the results of the assessment of the effect of damage during installation (DDI) on the short-term mechanical behaviour and on the soil-geosynthetics interface strength of a biaxial woven polyester ge-ogrid. This material has been subjected to field damage tests, using two different soils and two compaction energies. To characterize the effect of the damage induced in the mechanical behaviour of geosynthetics, ten-sile tests (short-term behaviour), were carried out, according with the procedures described in EN ISO 10319. Simultaneously a test program was implemented to carry out pullout tests (according with EN 13738) and in-clined plane shear tests (EN ISO 12957-2) to characterize the strength of the soil-geosynthetic interface. The results of the study are presented and analysed. The values of the corresponding reduction factors to consid-erer the effects of DDI are also presented. Finally, the main conclusions are put forward.

2012Conference object

Restricted access

Effect of damage during installation on the pullout behaviour of geosynthetics

Publication . Araújo, Luís M.A.; Paula, António Miguel; Pinho-Lopes, Margarida; Lopes, Maria de Lurdes

Two geosynthetics were subjected to the effect of damage during installation (DDI) using real conditions, when installed in experimental works. The effects of the damage induced on the geosynthetics by these procedures were evaluated using wide-width tensile test. Simultaneously a test program was implement-ed to carry out pullout tests (according with EN 13738: 2004) to characterize the behaviour of the soil-geosynthetic interface. The geosynthetics tested include two different materials with different structures. The effects of DDI on the pullout behaviour of the geosynthetics is presented and discussed. The values of the re-duction factors determined from the results obtained are also presented. The main conclusions are stated.

2010Conference object

Open access