Experimental and Numerical Investigation of Blast‐Induced Vibration for Short‐Delay Cut Blasting in Underground Mining

Abstract

It is essential to control the damage to the surrounding rock and engineering structures in the process of cut blasting with a single free surface in underground mining. To reduce vibration induced by cut blasting, this paper proposes short-delay cut blasting, in which blast holes that are near each other are sequentially initiated with short-delay times. Experimental tests of cut blasting were conducted in a roadway in the Shaxi copper mine to compare the peak particle velocity (PPV) and frequency characteristics of simultaneous blasting and short-delay blasting. Numerical modelling was then developed to study the influence of short-delay times on blast vibration. The accuracy of the numerical simulation was verified by the comparison of the test and simulated data of single-hole blasting. The results show that the amplitude reduction ratio (ARR) value increases gradually with the increase in delay intervals, and the vibration reduction for delay intervals smaller than 6 ms is very limited, particularly in the near field. The principal frequencies (PFs) for short-delay blasting are similar to those for simultaneous blasting, which implies that the frequencies do not increase directly with the decrease of the delay intervals. The experimental tests also show that the mean frequencies (MFs) for the 8 ms delay are slightly higher than those for the 0 ms delay blast. In the case of ensuring the rock breaking of cut blasting, longer delay intervals of 8∼10 ms are beneficial to further reduce PPV in practical blasting.

Blasting Vibration Control and Signal Analysis of Adjacent Existing Deterioration Tunnels

“…After the decomposition and reconstruction of vibration signals from nodes (7,0) to (7,3) in the x direction of measurement point 1, the vibration velocity and spectrum are shown in Figures 16 and 17 From the spectrum diagram, the blasting vibration frequency is mainly concentrated in the range of 0~250 Hz, and the first 16 frequency bands after wavelet packet decomposition are reconstructed. After the decomposition and reconstruction of vibration signals from nodes (7,0) to (7,3) in the x direction of measurement point 1, the vibration velocity and spectrum are shown in Figures 16 and 17 From the spectrum diagram, the blasting vibration frequency is mainly concentrated in the range of 0~250 Hz, and the first 16 frequency bands after wavelet packet decomposition are reconstructed. After the decomposition and reconstruction of vibration signals from nodes (7,0) to (7,3) in the x direction of measurement point 1, the vibration velocity and spectrum are shown in Figures 16 and 17 It can be seen from Figures 16 and 17 that the vibration velocity and frequency distribution of each interval can be clearly seen after the decomposition and reconstruction of the wavelet packet.…”

“…After the decomposition and reconstruction of vibration signals from nodes (7,0) to (7,3) in the x direction of measurement point 1, the vibration velocity and spectrum are shown in Figures 16 and 17 From the spectrum diagram, the blasting vibration frequency is mainly concentrated in the range of 0~250 Hz, and the first 16 frequency bands after wavelet packet decomposition are reconstructed. After the decomposition and reconstruction of vibration signals from nodes (7,0) to (7,3) in the x direction of measurement point 1, the vibration velocity and spectrum are shown in Figures 16 and 17 It can be seen from Figures 16 and 17 that the vibration velocity and frequency distribution of each interval can be clearly seen after the decomposition and reconstruction of the wavelet packet. It can be seen from the vibration velocity and spectrum diagram of the first four nodes that the peak vibration velocity is at node (7,2), and the peak frequency is at node (7,3).…”

“…It can be seen from Figures 16 and 17 that the vibration velocity and frequency distribution of each interval can be clearly seen after the decomposition and reconstruction of the wavelet packet. It can be seen from the vibration velocity and spectrum diagram of the first four nodes that the peak vibration velocity is at node (7,2), and the peak frequency is at node (7,3). The vibration velocity and spectrum in three directions of 16 nodes at measuring points 1 and 2 are shown in Figure 18.…”

“…Li [5] and Tang [6] pointed out that the key to decreasing the vibration of differential blasting is the control of differential time. Yang [7] and Ma et al [8] used ANSYS/LS-DYNA software, version 19.2, to simulate the reasonable micro-difference time between deep hole blasting and shallow hole blasting. It is proved that the precision delay between holes based on a digital electronic detonator is better than the simultaneous detonation of holes.…”

Full Waveform Prediction of Blasting Vibration Using Deep Learning

“…Blasting technology has been widely used in engineering projects such as water conservancy, transportation, construction, and mining. Currently, blasting is one of the most commonly used techniques in mining or stone excavation projects [1][2][3]. The development of engineering blasting technology has greatly reduced the labor intensity, accelerated the speed of project construction, and improved work efficiency; however, the impact of blasting on ground vibration, flying stones, air shock waves, noise, and dust on the surrounding environment has also become increasingly prominent.…”