Underground Space (Dec 2022)
Study on influencing factors and prediction of peak particle velocity induced by roof pre-split blasting in underground
Abstract
Blasting technology is widely used to prevent coal bursts by presplitting the overburden in underground coal mines. The control of blasting intensity is important in achieving the optimal pre-split effectiveness and reducing the damage to roadway structures that are subjected to blasting vibrations. As a critical parameter to measure the blasting intensity, the peak particle velocity (PPV) of vibration induced by blasting, should be accurately predicted, and can provide a useful guideline for the design of blasting parameters and the evaluation of the damage. In this paper, various factors that influence PPV, induced by roof pre-split blasting, were analyzed using engineering blasting experiments and numerical simulations. The results showed that PPV was affected by many factors, including charge distribution design (total charge and maximum charge per hole), spacing of explosive centers, as well as propagation distance and path. Two parameters, average charge coefficient and spatial discretization coefficient were used to quantitatively characterize the influences of charge distribution and spacing of explosive centers on the PPV induced by roof pre-split blasting. Then, a model consisting of the combination of artificial neural network (ANN) and genetic algorithm (GA) was adopted to predict the PPV that was induced by roof pre-split blasting. A total of 24 rounds of roof pre-split blasting experiments were carried out in a coal mine, and vibration signals were collected using a microseismic (MS) monitoring system to construct the neural network datasets. To verify the efficiency of the proposed GA-ANN model, empirical correlations were applied to predict PPV for the same datasets. The results showed that the GA-ANN model had superiority in predicting PPV compared to empirical correlations. Finally, sensitivity analysis was performed to evaluate the impacts of input parameters on PPV. The research results are of great significance to improve the prediction accuracy of PPV induced by roof pre-splitting blasting.
