A bar explosion model based on continuous–discontinuous element method and its application in blasting excavation

Blasting excavation is widely used in engineering, often involving complex hole layouts. However, the small size of the blasthole and the large size of the three-dimensional (3D) numerical model lead to the large calculation scale of the 3D blasting numerical simulation, which requires considerable calculation time. Typically, a 3D numerical model is simplified into a two-dimensional (2D) numerical model, and a 1/2- or 1/4-scale model can be adopted to reduce the calculation scale. To solve this problem, a one-dimensional bar explosion model is adopted to replace the traditional solid explosion model under the framework of the continuous–discontinuous element method. The detonation pressure is directly distributed to the elements penetrated by the bar, and the volume expansion of the elements is used to calculate the volume expansion attenuation detonation pressure at each stage of detonation, thus avoiding the problem of local mesh refinement. Compared with the solid explosion case, the reliability of the bar explosion model is verified by the propagation of the explosion stress wave, peak explosion pressure, and damage nephogram. In combination with the engineering background, three blasting conditions are simulated, and the optimal one is evaluated based on fracture degree and blast fragment size pass rate.