This study proposes a biconcave-shaped bonding model for distinct element method (DEM) to simulate cementation efficacy between two circular particles in geo-materials such as intact sedimentary rock. Instead of original parallel bonding model between particles, the proposed model adopts the more realistic shape of cementation and considers the elastic response of cementation under external loading. The stress field and force-displacement relationship of biconcave-shaped bonding is based on the Dvorkin's theory, a modification superposition method was applied to improve the correctness and symmetry of the stress field. This method also replaces the tangential movement to normal and rotation in particle's motion, in this way the corresponding total displacements in cementation can be obtained and updated easily. To assess the validity of modified Dvorkin's theory, we compared its elastic mechanical behaviors with the numerical elasticity analysis in finite element method. After verifying the proposed model, a series of sensitivity analysis was performed to discover the effect of bonding shape and to explore the difference with previous studies. Furthermore, the proposed model has been implemented in DEM software PFC2D to certify its applicability in geotechnical practice. The results show it works well with different bonding shape and it can represent the mechanical behavior of biconcave-shaped cementation. The stress field calculated by modified Dvorkin's theory is more similar with FEM result and able to solving the reaction when two particles are both moving. In addition, the required parameters can be acquired from real bonding material instead of back calculation from laboratory experiments. This model provides an innovative way to simulate the behavior of cemented granular material.

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