Theoretical Study on Radial Distribution Laws of Rock Mass Damage Factors under Decoupled Charge Blasting

Abstract

In this paper, the radial distribution laws of damage factors under decoupled charge blasting are studied for the optimization design of blasting parameters. Through defining the critical radial decoupling coefficient, the damage zone around the borehole is partitioned and the characteristics are described. Based on the damage factor defined by Taylor’s effective elastic modulus, the formulas of the radial distribution laws of damage factors are derived by the attenuation law of stress wave and the theory of thick-walled cylinder, respectively, which are then superposed to obtain the formula under the combined action of explosion stress wave and quasistatic gas. Experimental verification indicates that the theoretical values, which have a good correlation with the test data and are of high accuracy, can characterize the radial distribution laws of damage factors and estimate the damage range. When a radial decoupling coefficient is less than the critical value, the attenuation rate of damage factors firstly increases and then decreases with the increase of distance, and a serious damage zone is caused. Conversely, it decreases gradually, and the serious damage zone is not caused. Therefore, on the premise of stable detonation, it is necessary to apply an appropriate radial decoupling coefficient which is larger than the critical value to smooth or presplit blasting.

Study on the Blasting Effect of Radial Uncoupled Parameters on Limestone

“…Gong Jiu et al [12] found that compared to air uncoupled charges, water uncoupled charges have a higher utilization rate of explosion energy and are more conducive to improving the blasting effect. Pan Qiang et al [13] found that the damage factor of uncoupled charge blasting decays in a power function, and the decay rate increases with the increase of uncoupled coefficient when K<K0. Zhang Liwei et al [14] found that as the spacing between holes increases, the degree of damage between the connecting lines of the blast holes decreases, and the damage area between the connecting lines changes from continuous to discontinuous.…”