At present, the design of geosynthetic-reinforced soil structures is executed with reference to the tensile strength of the reinforcement obtained from in-air short-term tensile tests, decreasing this value by means of several factors. Among these, the creep effect resulting from in-air tensile creep tests reduces tensile strength the most. Consequently, this procedure does not take into account the effects of soil confinement and interaction on the tensile response of the reinforcements. This paper illustrates a new large-scale pullout prototype apparatus, with the capacity to investigate the behaviour of a geosynthetic reinforcement embedded in a compacted soil and subject to a tensile load kept constant over time. The apparatus allows the verification of how the soil can modify the prediction of the long-term behaviour of geosynthetics. Results in terms of confined tensile strains were analysed, and the comparison of those values with the strains obtained by in-air tensile creep tests has led to the conclusion that the creep reduction factor might be conservative. Moreover, the confined tensile strains were related to the apparent coefficients of friction to propose a new procedure capable of determining the design interaction parameter under long-term pullout load as a function of the allowable reinforcement strains.

目前，土工合成材料加筋土结构的设计参考了空中短期拉伸试验得到的加筋抗拉强度，通过多种因素降低了该值。其中，空气中拉伸蠕变试验产生的蠕变效应降低了拉伸强度。因此，该程序没有考虑土壤约束和相互作用对钢筋拉伸响应的影响。本文展示了一种新的大型拉拔原型设备，它能够研究嵌入压实土壤中的土工合成材料加筋的行为，并承受随时间保持恒定的拉伸载荷。该设备可以验证土壤如何改变对土工合成材料长期行为的预测。分析了受限拉伸应变方面的结果，并将这些值与通过空中拉伸蠕变试验获得的应变进行比较，得出的结论是蠕变折减系数可能是保守的。此外，受限拉伸应变与表观摩擦系数有关，以提出一种新程序，该程序能够确定长期拉拔载荷下的设计相互作用参数，作为容许钢筋应变的函数。