Numerical study of decoupling charge drilling and blasting under high stress conditions

The inherent characteristics of plateau stress impose constraints on the expansion of rock cracks induced by blasting operations. Utilizing decoupling blasting in deep rock excavation projects can significantly alter the outcomes of rock blasting. This study conducted comprehensive analyses for investigating the impacts of both concentric and eccentric decoupling on rock damage with the aim of identifying the optimal concentric/eccentric decoupling coefficient (DC). Special attention was given to numerically evaluating the mechanical response characteristics of the DC under conditions of biaxial and anisotropic stress during single-hole blasting. The study also explored the influences exerted by lateral pressure coefficient (LPC), burial depth, and hole configuration on the propagation of rock cracks. The findings reveal that under the combined influence of equal biaxial in-situ stress (ISS) and explosive loading, the inhibitory effect on crack propagation becomes more pronounced as ISS increases. Concurrently, both radial and circumferential compressive stresses show a general upward trend, alongside a reduction in the damage range. A rise of the transverse pressure coefficient causes both radial and circumferential stresses to rise, with cracks generated by blasting tending to expand preferentially in the direction of higher stress. When the burial depth reaches 1000 m and the LPC ranges between 0.25 and 3.0, joint cracks can be formed. Furthermore, when the angle between the centerline of adjacent boreholes and the horizontal direction ranges from 0° to 45°, the cracks between boreholes interconnect; however, at angles from 60° to 90°, the cracks do not penetrate. Notably, increases in burial depth and angle are found to increasingly restrict the penetration of cracks between holes. These results provide valuable insights for predicting and optimizing rock blasting behavior.