Abstract: The radial uncoupled charge structure is widely used in practical blasting engineering. In order to explore the variation law of the impact pressure of the hole wall of the radial uncoupled charge,based on the shock wave theory,the shock tube model is used to simplify the action process of the wave system in the hole under the condition of the radial uncoupled charge. The impact pressure of the blast wave in the hole on each medium surface is studied. The calculation expression of the initial impact pressure of the hole wall under the condition of radial uncoupled charge is obtained,and the action process of the blast wave under the condition of radial uncoupled charge is simulated. The results show that the existence of the radial air layer greatly reduces the pressure of the explosion shock wave. The peak pressure of the hole wall decays exponentially when the uncoupling coefficient is 1~2,and the decay rate is slow when the uncoupling coefficient is greater than 2. There are multiple peaks when the shock wave acts on the hole wall,and the initial peak pressure is the largest,and the subsequent peak pressure gradually decreases with time. With the increase of the uncoupling coefficient,the initial peak pressure gradually decreases and the time to reach the peak pressure gradually delays. The larger the uncoupling coefficient is,the more obvious the multi-peak characteristics are. When the uncoupling coefficient is small,the peak pressure is larger,which will cause greater damage to the surrounding rock. In order to reduce the damage to the surrounding rock and meet the corresponding blasting requirements,the multi-peak characteristics when the decoupling coefficient is large should be fully utilized,and a reasonable radial charge coefficient should be selected according to the rock properties.

Key words: radial uncoupled charge,uncoupling coefficient,impact pressure on hole wall,numerical simulation