Optimization And Application Of Reasonable Delay Time Of Bench Blasting Based On Electronic Detonator

At present,electronic detonators have been widely promoted and used in various blasting projects in China.With the accuracy of their delay time,electronic detonators have become a new method and means of studying millisecond blasting,and also a crucial step in promoting the construction of intelligent mines.In open-pit mine bench blasting,the selection of delay time directly affects the blasting fragmentation and blasting vibration effect,thereby affecting mine safety and enterprise efficiency.This article combines the foundation of previous research and relevant blasting theories to optimize the calculation formula for the reasonable inter hole delay time of open-pit mine bench blasting.The accuracy of the calculation results is tested through concrete model experiments and numerical simulations.Relevant experiments are conducted on the blasting site to verify its feasibility,optimize the delay time of the blasting site,and improve the blasting effect.Based on large-scale concrete test blocks,model experiments were conducted,and reasonable inter hole delay times were calculated based on the blasting parameters of the model experiments.Based on this,six experimental plans were designed,with inter hole delay times of 0ms,1ms,2ms,3ms,4ms,and 5ms,respectively.Monitor the blasting vibration effect during the experiment and collect rock fragments for statistical analysis;Using high-speed photography and digital image related methods to track and calculate the strain on the surface of the step,and studying the strain relationship between adjacent boreholes under different delay time conditions between boreholes;Then simulate and analyze the model experiment using ANSYS/LS-DYNA,analyze the pressure distribution and degree of fragmentation of the rock mass after blasting,and obtain corresponding laws;Finally,based on model experiments and numerical simulations,on-site blasting experiments were designed to verify the accuracy of the results.The main achievements are as follows:(1)By using digital image correlation methods to calculate the displacement of speckle on the surface of the model,the strain duration near the surface crack of the model under explosive load is about 3ms.At this time,the initiation of the next blast hole can maximize the interaction force between the blast holes and the joint action time between the blast stress wave and the explosive gas.The explosive crack is fully expanded,which is conducive to rock fragmentation.(2)The finite element analysis software ANSYS/LS-DYNA was used to simulate the model experiment,and the results clearly displayed the distribution characteristics and fragmentation degree of cracks under different delay time conditions,revealing the pressure distribution characteristics of different measurement points.Except for simultaneous detonation,when the delay time between holes is 1ms and 3ms,the pressure on the measuring point is the highest;By binarizing the simulation results using MATLAB,it was found that the optimal degree of rock fragmentation was achieved when the delay time between holes was 3ms.(3)Combined with model experiment and numerical simulation,the blasting field experiment was designed,and the blasting fragmentation and blasting vibration effect were analyzed.For Wuwei Yangjialing Mine,the delay time between control holes was35ms～40ms,which could achieve a better block Degree distribution;When the delay time between holes is 40 ms,the blasting vibration energy is the lowest.The experimental results verify the accuracy of the theoretical calculation formula,optimize the on-site delay time between holes,and improve the blasting effect of the mine.Figure[40] Table[18] Reference[84]...