A method for evaluating the failure state of geomaterials in DEM by introducing equivalent Cauchy stress and macro strength criterion

Discrete Element Method (DEM) can well simulate the failure of geomaterials, but it is challenging to evaluate its stable degree and failure state. An approach for calculating the equivalent Cauchy stress field in both regular and irregular DEM models is proposed by establishing a local equivalent element for each particle. Meanwhile, the relationship between the stress ratio path during geomaterial failure and the macro strength criterion is analyzed, and then, a new evaluation index named SF_SRP is proposed. Combining the equivalent Cauchy stress and the SF_SRP, a method that can evaluate the stable degree and failure state of the geomaterial is established. Finally, the proposed method is implemented to analyze the failure process in four typical cases, including a trapdoor test, a retaining wall test, a tunnel excavation test, and a biaxial compression test, based on PFC2D. The results demonstrate that the proposed method not only presents the failure location intuitively but also quantitatively reflects the stable degree and failure state in the DEM model.