In order to improve the mechanical properties of the sand layer in the GRPM pipe and enhance its designability,a representative volume element model was constructed to reproduce its mesoscopic structure characteristics by means of finite element simulation software,and the zero-thickness cohesive element was inserted into the model to realize the complex and discrete multi-crack initiation and expansion of the model. The uniaxial tensile fracture process of the sand layer specimen was simulated,the microscopic fracture damage evolution processwas analyzed, and the influence of each component parameter on the fracture mechanical behavior of the sand layer was explored. The research results show that cohesive fracture model can better characterize the complex fracture process of sand layer. During axial tensile deformation,the main crack of the material is approximately perpendicular to the loading direction,accompanied by interfacial debonding and cracks propagation in the matrix. The crack propagation direction is mainly affected by the position of the particle distribution,increasing its volume fraction can improve the stiffness of the material. The enhancement effect of multi-particle size distribution is better than that of single particle size distribution,the smaller the particle size,the better the reinforcement and toughening effect. The increase of the tensile strength and fracture energy of the cohesive unit can improve the overall tensile strength of the model. The larger the crack path,the simpler the crack path. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.