Study on the stress wave superposition mechanism and multi-polar zoning method for action zones under multi-point simultaneous explosions

Multi-point explosions in rock media generate complex wave interference and coupling effects, leading to energy concentration and pressure enhancement in specific regions, which poses a serious threat to the safety of underground spaces. Based on the fundamental principles of shock wave propagation and superposition, this study conducted multi-point explosion model tests in similar material for soft rock, combined with finite element numerical simulation analysis, to systematically investigate the superposition and propagation behavior of stress waves under multi-point explosion conditions. Utilizing gas dynamics theory and wave system decomposition and synthesis, the stress wave action zones were delineated. The results indicate that the peak pressure of shock waves from multi-point explosions initially increases and then decreases with increasing standoff distance. Under equivalent charge mass, the peak pressure within the multiple stress wave superposition zone can reach 3–4 times that of a single-point explosion. An equivalent calculation method for the multi-shock wave load model was established based on orthogonal wave decomposition and synthesis theory. The effective range of multiple stress waves was determined through curvature analysis. The pressure field of multi-point simultaneous explosions was divided into four characteristic zones: the independent source zone, the Mach reflection zone, the multiple stress wave superposition zone, and the far-field attenuation zone. Finally, a parameter ζ describing the degree of energy concentration was defined, and a method for calculating the optimal energy concentration coefficient was proposed. This study provides a novel design concept for the quantitative assessment of damage effects in multi-point explosions and for the protective design of underground structures.