Evolution of stress field in cylindrical blasting with bottom initiation

The dynamic caustic method and numerical simulation method were used to study explosive stress field of cylindrical blasting with bottom initiation. The explosive stress distribution of cylindrical blast holes with bottom initiation was not uniform, and can be divided into side areas with stronger stress and end areas with weaker stress with notable end effects. In the side areas, the explosive stress field at the initiating end increased, and the stress was high at the initial stage after initiation. However, the stress field at the non-initiating end was the strongest with the explosive detonation wave propagating from initiating end to non-initiating end. Differences in the principal stress difference near the blast hole were significant. The explosive stress field in the initiating end was weaker than that in the non-initiating end. Caustic spots increased and maximum principal stress directions is consistent with crack propagation direction when cracks propagated near circular holes. According to the simulation results, the Mises stress wave has a "conical" distribution. The Mises stress attenuation coefficient in the vertical direction, the axial direction, and the oblique direction increased at initiating end. The Mises stress attenuation coefficient in vertical direction, oblique direction, the axial direction increased at non-initiating end.