中文摘要：

纤维加筋土具有较好的应用前景，其应力应变本构关系是工程分析与设计的基础。将纤维加筋土考虑为基本相和纤维相的组合体，分别采用修正剑桥模型和线弹性模型，考虑了大应变时纤维加筋土的屈服，引入了加筋土的合理强度模型作为破坏准则，从而建立了纤维加筋土的一种两相本构模型。同时，开展了纤维体积含量为1％的加筋砂的三轴固结排水剪切试验，对该两相本构模型进行了验证。

英文摘要：

The fiber reinforced soil has good application prospects, and its stress-strain constitutive model is the basis of engineering analysis and design. A two-phase constitutive model for the fiber-reinforced soil is developed considering the fiber-reinforced soil as a kind of composite materials comprising of basic phase and fiber phase using the modified Cambridge model and the linear elastic model respectively. A reasonable strength model is introduced as the failure criterion for the fiber-reinforced soil, and fiber reinforcement weakening at large strain is also taken into account. At the same time, consolidated drained triaxial shear tests on reinforced sand with fiber volume fraction of 1% are performed. The two-phase constitutive model is validated, and the results are in good agreement with the experimental data.