Analysis of the Main Factors Influencing the Dominant Frequency of Blast Vibration

At present, the study on the dominant frequency of blasting vibration is still a worldwide problem. Compared with the mature research on the particle peak velocity of blasting vibration, the researches on the dominant frequency of blasting vibration are much less. In this paper, by analyzing the main influencing factors of the dominant frequency, an attenuation equation of the dominant frequency induced by blasting vibration has been proposed by dimensional analysis combined with the theory of radial spherical wave propagation. The proposed equation is applied to the fitting analysis on the dominant frequency measured in Zhoushan Green Petrochemical Base in China, which has obtained a favorable fitting correlation. Based on the fitting analysis, it has found that the correlation coefficient of radial vibration obtained by the proposed equation is higher than that of vertical vibration, which is resulted from the reason that the vibration in vertical is considered to be influenced most by the R-wave on the ground and perceived to be quite different from the radial vibration affected by P-wave. In generally, different components of blasting waves will affect the attenuation of dominant frequency

Mathematical and Mechanical Analysis of the Effect of Detonator Location and Its Improvement in Bench Blasting

The outcome of bench blasting significantly affects the downstream operations in mining. In bench blasting, the explosives charged in blastholes are generally cylindrically shaped and fired by the in-hole detonator. As the detonator determines the propagation of the detonation wave in the cylindrical charge, the effect of detonator location can never be ignored. In this paper, the mathematics and mechanics of the effect of detonator location was analyzed from the view of the distribution of explosion energy and blast stress field of a cylindrical charge. Then, a field blasting experiment and two numerical simulations were conducted to further display its effect on blasting outcomes. At last, the appearance of oversize boulders and rock toes in bench blasting was discussed, and an improved scheme of the detonator location was proposed to cope with these problems. Results indicate that the in-hole detonator has the capacity of adjusting the spatial distribution of explosion energy and blast stress field in the surrounding rock mass. The traditional recommendation of the bottom detonator is not always right. The optimized detonator location in bench blasting is available by properly combining the merits of traditional detonator locations. This study is of interest to improve the efficiency and reduce the cost of mining