Influence of Charge Uncoupling Coefficient on the Throwing Movement of Broken Blocks in Bench Blasting

In open-pit bench blasting, the spatiotemporal movement law of broken blocks and energy consumption are crucial indicators of blasting effectiveness. This study adopts basic theoretical methods and constructs energy consumption calculation formulas based on the movement trajectory of broken blocks to address the issue of movement velocity and energy consumption of broken blocks under varying uncoupling coefficients. Then, combined with model experiments, it systematically examines the changes in movement velocity and energy consumption of blasting-induced broken blocks under different uncoupling coefficients. The research results indicate that after explosive initiation, cracks initially appear in the rock mass at approximately 2 ms and accelerate to completion within about 20 ms. The free surface of the rock mass exhibits a bulging shape, with lower elevations on the upper and lower sides and a higher elevation in the middle. The movement velocity of broken blocks follows a regular pattern over time and can be broadly divided into three phases: acceleration, dynamic uniform velocity, and throwing deceleration. The broken blocks reach their initial throwing velocity and kinetic energy at around 18 ms. After this point, they are largely unaffected by explosive products and move freely under the influence of gravity. Based on model test results and calculations, the kinetic energy of the throwing process under different uncoupling coefficients is determined, revealing that the proportion of total energy generated by the explosion ranges between 5% and 16%. The throwing kinetic energy and its proportion decrease as the uncoupling coefficient increases. When the uncoupling coefficient rises from 1.250 to 3.375, the throwing kinetic energy decreases from 3.06 to 1.12 kJ, while the throwing kinetic energy proportion declines from 15.26% to 5.58%. These findings provide theoretical guidance and engineering application value for rock fragmentation, the movement law of broken blocks, and energy consumption distribution under uncoupled charging conditions in open-pit bench blasting.