Creep rupture curve for simultaneous creep deformation and degradation of geosynthetic reinforcement

Abstract

The viscous property of polymer geosynthetic reinforcement, which causes creep deformation, is first summarised. The creep deformation and associated creep rupture characteristics, when subjected to long-term sustained loading under the following three conditions, are numerically simulated based on a non-linear three-component rheology model: (a) the load–strain behaviour is always free from material degradation; (b) the load–strain behaviour exhibits simultaneous viscous effects and material degradation as in usual actual field cases; and (c) the sustained loading starts after full material degradation has taken place. Case (c) is the one assumed in the currently most popular design method, in which the long-term tensile design strength is obtained by separately applying reduction factors for creep rupture and material degradation. This method underestimates the true creep rupture strength to an extent that depends on the viscous and material degradation properties of the geosynthetic reinforcement. In this paper a new method to obtain the design tensile strength is proposed, taking into account the new creep–rupture curve for simultaneous creep deformation and degradation. The viscous property of polymer geosynthetic reinforcement, which causes creep deformation, is first summarised. The creep deformation and associated creep rupture characteristics, when subjected to long-term sustained loading under the following three conditions, are numerically simulated based on a non-linear three-component rheology model: (a) the load–strain behaviour is always free from material degradation; (b) the load–strain behaviour exhibits simultaneous viscous effects and material degradation as in usual actual field cases; and (c) the sustained loading starts after full material degradation has taken place. Case (c) is the one assumed in the currently most popular design method, in which the long-term tensile design strength is obtained by separately applying reduction factors for creep rupture and material degradation. This method underestimates the true creep rupture strength to an extent that depends on the viscous and material degradation properties of the geosynthetic reinforcement. In this paper a new method to obtain the design tensile strength is proposed, taking into account the new creep–rupture curve for simultaneous creep deformation and degradation.