The Influence Of The Minimum Resistance Line And The Different Length-diameter Ratio Of The Charge On The Step Blasting

There are many factors that affect the effect of bench blasting,such as the size of the minimum resistance line and the length-to-diameter ratio(dose)of the drug package.In order to study the specific impact on the bench blasting,similarity theory is used to establish the similarity criteria,and a plain concrete step model is demolition.The test,combined with high-speed photography technology,vibration testing technology and super dynamic strain measurement technology,was tested and analyzed.The results are as follows:With the increase of the minimum resisting line,the total mass and maximum mass of the squid tend to increase;when the length-to-diameter ratio(dose)of the drug packet increases,the length of the crater increases,and the diameter of the crater does not change.Four times the diameter of explosives,the overall quality of the blasting pile and the uniformity index of the blockiness increased first and then decreased.The complete motion process of the free surface of the step model during blasting was collected by a high-speed photography system.The contour curves of the bulge at different times were plotted and the rock motion velocity of the free surface was calculated.After the resistance line increases,the rock motion speed will decrease.The greater the resistance line is,the slower the speed will decrease,the final speed will approach zero,the angle between the point velocity of the model charge center and the horizontal direction will gradually decrease,and the larger the resisting line angle,The slower the decrease.With the increase of the length-diameter ratio of the charge,the speed increase of the top of the model gradually decreases,and the speed of the increase of the speed of the center of the drug package in the free surface projection position gradually increases.Using the hyperdynamic strain system to test the strain at different positions on the free surface of the step model,the strain propagation law was obtained.The peak strain on the free surface decreases with increasing distance from the source,and the faster the distance,the faster the attenuation.At the same distance,the position of the free surface changes the distribution of stress.The vibration test on the step model shows that,when the distance from the source is the same,the maximum vibration speed of the resistance line increases within a certain range and then increases first and then decreases.In each model with different aspect ratios(drug doses),the maximum vibration velocity in three directions is X(radial)> Z(vertical)>(tangential),with the aspect ratio(medicine With the increase in the amount,the main vibration frequencies in all three directions have decreased.The LS-DYNA simulation software was used to establish the model of bench blasting with different minimum resistance lines.After numerical calculation,it was found that the free surface velocity and strain were consistent with the test results.