Simple constitutive models to study the influence of installation damage on the load-strain response of two geogrids
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abstract
A key factor affecting the tensile response of geosynthetics is installation damage, repre-sented by a reduction factor capturing changes in tensile strength. Although often geosynthetics are repre-sented in numerical models by simple linear-elastic constitutive models and a stiffness, the response of geosynthetics to loading can be represented more realistically by non-linear constitutive models. Herein, simple constitutive models were used to represent the short-term tensile response of two geogrids (woven geogrid and uniaxial extruded geogrid). The tensile response of samples exhumed after field installation under real conditions was compared to that of the corresponding undamaged samples (as-received). The changes in response, particularly the change in tensile strength and stiffness, were presented and dis-cussed. The polynomial models (order 6) approximated the experimental data better than the hyperbolic models. Contrary to what has been reported in the literature, for the materials and test conditions present-ed herein and for the hyperbolic models, the parameter b cannot be estimated as the inverse of the materi-als tensile strength and the parameter is not a material constant. Both polynomial and hyperbolic mod-els approximated well the tangent stiffness for 2% strain obtained experimentally. The model parameters were normalised to the reduction factor for installation damage; for the hyperbolic models, the parameter b was practically unchanged after exhumation of the samples, while parameters a and showed no clear trend; the values of the stiffness normalised to the reduction factor for installation damage were not con-stant.
