Fiber reinforcement techniques can effectively optimize the engineering properties of ground soils. This study aims to investigate the influence of fiber stiffness on the shear behavior of fiber-reinforced granular soil. First, the particle shapes are automatically extracted based on the improved Viola–Jones algorithm. Subsequently, the fiber stiffness is calibrated considering the results of laboratory tensile tests. Moreover, a series of numerical biaxial tests are conducted considering different fiber stiffnesses and contents and a flexible boundary. The influence of the fiber stiffness on the strength and volumetric strain is analyzed, and the stress–dilatancy relationship of the fiber-reinforced soil is discussed. In addition, the interaction between the fibers and soil particles is clarified according to the internal structure and stress network, including the coordination number, contribution of the contact, sliding of the particles and mobilization of the tensile force in the fibers. The results of this study can help clarify the reinforcement mechanism of fibers with typical stiffness values.

纤维加固技术可以有效优化地基土的工程性质。本研究旨在研究纤维刚度对纤维增强颗粒土剪切行为的影响。首先，基于改进的 Viola-Jones 算法自动提取粒子形状。随后，考虑实验室拉伸试验的结果校准纤维刚度。此外，考虑到不同的纤维刚度和含量以及柔性边界，进行了一系列数值双轴试验。分析了纤维刚度对强度和体积应变的影响，讨论了纤维增强土的应力-剪胀关系。此外，根据内部结构和应力网络，阐明了纤维与土壤颗粒之间的相互作用，包括配位数、接触的贡献、颗粒的滑动和纤维中张力的移动。本研究的结果有助于阐明具有典型刚度值的纤维的增强机制。