Abstract: Aiming at the anisotropic characteristics of frozen soil, this paper established a modified linear bond contact model that can reflect the anisotropic characteristics of frozen soil based on the linear bond contact model, and generated a discrete element constitutive subroutine (DLL) for particle flow program (PFC^3D) calls through C++. Firstly, tensile and shear stimulations were carried out on a single contact. By comparing numerical and theoretical results, the calculation accuracy of the modified linear bond contact model for frozen soil considering orthotropic was verified. In addition, the triaxial compression tests of frozen soil at different temperatures were simulated and compared with the stress-strain curves obtained from the tests. The results show that the proposed modified linear bond contact model has good applicability to frozen soil. Based on the calibrated meso-parameters of the model, a series of triaxial compression discrete element numerical simulations was carried out. Using the simulation results, the influences of the inclination of the virtual weak surface on the stress-strain curve characteristics, strength and shear strength indexes of frozen soil were discussed, and the evolution laws of effective coordination number and meso-fabric quantity were analyzed. The research results can provide a basis for using numerical methods to study the orthotropic macro meso-mechanical properties of frozen soil.

Key words: frozen soil, particle discrete element, modified linear bonding model, secondary development, anisotropy