Discontinuous deformation analysis (DDA) method is a discrete element method, presenting a great advantage in modelling deformation and rigid body movements, and it is also an alternative approach for problems involving the fracturing process from continuity to discontinuity if the failure mechanism in DDA is well constituted. This paper presents a new united tensile fracture model (UTFM) for the two-dimensional DDA method to simulate the fracture behaviors of various brittle materials (e.g., rock, soil, and concrete). The new fracture model unifies four classical failure modes, including the maximum normal stress criterion, Tresca criterion, Mohr–Coulomb criterion, and the von Mises criterion, for tensile fracture. By incorporating UTFM into the original DDA frame, the improved DDA (I-DDA) can predict the crack initiation and propagation paths in Brazil disc and simulate rock fracture of various brittle materials. Numerical examples of the direct tensile test and the Brazil disc split tests are investigated to verify the accuracy and validity of the I-DDA method. The simulated results agree well with those obtained from physical tests and other numerical analyses, suggesting that the I-DDA has obvious advantage in simulating the fracture behaviors of the Brazil disc split test. Further, the I-DDA is applied to analyze the failure process of a practical earthquake-induced landslide with consideration of the tensile strength of the rock mass. The results indicate that the I-DDA is more feasible to analyze the slope failure, which can consider both the tensile and shear characteristics simultaneously compared with the original DDA.

中文翻译：

---

用新的统一拉伸断裂模型改进 DDA 用于岩石破碎及其在动力地震滑坡中的应用

不连续变形分析（DDA）方法是一种离散元方法，在模拟变形和刚体运动方面具有很大的优势，如果DDA中的破坏机制很好，它也是解决从连续到不连续的破裂过程问题的一种替代方法构成。本文提出了一种新的联合拉伸断裂模型 (UTFM)，用于二维 DDA 方法来模拟各种脆性材料（例如，岩石、土壤和混凝土）的断裂行为。新的断裂模型统一了四种经典破坏模式，包括最大法向应力准则、Tresca 准则、Mohr-Coulomb 准则和 von Mises 准则，用于拉伸断裂。通过将 UFM 合并到原始 DDA 框架中，改进的DDA（I-DDA）可以预测巴西盘中裂纹的萌生和扩展路径，模拟各种脆性材料的岩石断裂。研究了直接拉伸试验和巴西盘劈裂试验的数值例子，以验证 I-DDA 方法的准确性和有效性。模拟结果与物理试验和其他数值分析的结果吻合较好，表明I-DDA在模拟巴西盘劈裂试验的断裂行为方面具有明显优势。进一步，应用I-DDA分析了实际地震滑坡的破坏过程，同时考虑了岩体的抗拉强度。结果表明I-DDA对边坡失稳分析更可行，