LAUSR

Abstract 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.