针对土工织物筋土接触面的软化和塑性流动现象，根据拉拔试验的结果，提出了剪应力—位移关系的三阶段弹塑性模型．由筋材的受力特性建立微分控制方程，并通过有限差分法进行求解，得到了拉拔试验中的非线性位移、应变、拉力和剪应力等参量．算例分析了拉拔试验中的拉拔力—位移关系，并与线弹性模型和双曲线模型分析的结果进行比较．结果表明，分阶段弹塑性模型分析更符合实际情况．

Based on the results of pull-out test on geotextiles, this paper presented a three-staged model for total shear stress-displacement to consider the strain softening and plastic flow. According to the mechanical characteristics of geotextiles, the non-linear differential equations are expressed in non-dimensional form and solved numerically using a finite difference method. The variation of the displacement, strain, tension and shear stress in pull-out test can be obtained. The relation between pull-out force and deformation was discussed based on the example analysis, and compared with the experimental pull-out test results. Comparison with the results of linear elastic model and hyperbolic model shows that three-staged elastic-plastic model is in good accord with practical situation.