Research On Impact Resistance Of Electronic Detonators In Cement Mortar Test Block And Its Application In Tunnel Excavation Blasting Engineering

In recent years,with the increasingly complex blasting environment and conditions,the requirements for blasting construction,the selection of blasting equipment and explosion safety are becoming more and more stringent.At present,the mainstream research in the field of blasting is millisecond blasting technology,which has high requirements for the delay accuracy of detonators.The emergence of digital electronic detonator can perfectly meet the above conditions and has extensive research value.In this paper,taking cement mortar test block as the carrier,the propagation law of stress wave in the process of explosion is measured by super dynamic strain gauge,and the stress and strain are calculated;In order to truly simulate the application environment of digital electronic detonator in tunnel blasting,it is placed in cement mortar test block,and its impact resistance at different distances is tested by changing the distance from the explosion source;Through the application of the same type of digital electronic detonators in large,medium and small sections of tunnel engineering,the causes of blind blasting are analyzed and solutions are put forward,and the blasting effects of the same type of digital electronic detonators produced by different factories are compared in the controlled blasting of small section tunnel.The following conclusions on this paper could be drawn through research:(1)Through the strain test at different distances,it is found that the stress wave transmission has the same law: the closer the measuring point is to the explosion source,the peak value of the measured voltage signal,strain and strain rate are the largest,and the farther the measuring point is from the explosion source,the peak value of the measured voltage signal,strain and strain rate decreases gradually.It also can be seen from the damage degree of the block test that the rock damage near the explosion source is serious,and the damage away from the explosion source is slight.The result shows that the stress wave transmission has a decreasing trend.(2)The experiment shows that the repeatability of super dynamic strain test is poor.The specific performance is that the waveforms between different measuring points in the same test block are similar,while the waveforms between the same measuring points in different test blocks are quite different.The reason for this phenomenon is that the super dynamic strain test has high requirements on the environment and too many uncertain factors of external conditions will lead to great differences in data acquisition waveforms.(3)The impact resistance of digital electronic detonator is better than that of industrial detonator.What’s more the impact resistance of digital electronic detonator coated with latex tube is improved,and the overpressure attenuation ratio of shock wave reaches 1.73.(4)The digital electronic detonator with or without latex tube coating are roughly divided into three parts according to different degrees of damage.All detonators will be sympathetic detonation within 1.3 cm from the explosion source,and will not be sympathetic detonation if they exceed this limit.When the distance within the range of1.3 ～ 3.0 cm from the explosion source,the electronic detonator loses the ignition ability due to different degrees of damage,especially when there is no damage outside the detonator but still loses the ignition ability 3.0 cm away from the main charge.When the distance within the range of 1.3 ～ 2.5 cm from the explosion source,the electronic detonator coated with latex tube loses the ignition ability due to different degrees of damage.When the distance between the electronic detonator and the explosion source is more than 3.0 cm,and the digital electronic detonator coated with latex tube is more than2.5 cm,the explosion shock wave will not affect its ignition ability,and the appearance is intact.(5)Electric detonators and Nonel detonators will be sympathetic detonation within1.7 cm from the explosion source,some of them will be sympathetic detonation at 2.0 cm away from the explosion source,and will not be sympathetic detonation when they exceed this limit.When the distance between the electric detonator and the explosion source is2.0 ～ 2.7 cm,the electric detonator will lose the ignition ability due to different degrees of damage.When the distance from the explosion source is 3.0 cm,there will be no obvious damage outside the detonator,but some will lose the initiation ability;When the distance between the nonel detonator and explosion source is 2.0 ～ 2.7 cm,it will be damaged to varying degrees and lose the ignition ability,and take 3.0 cm as the safety threshold for normal initiation of the detonator;If the electric detonator is more than 3.3cm away from the explosion source and the nonel detonator is more than 3.0 cm away from the explosion source,its ignition ability will not be affected by the action of explosion shock wave.(6)Through the practical application of digital electronic detonator in tunnel excavation blasting,it is obtained that it can not only realize millisecond millisecond millisecond blasting,reduce blasting vibration,uniform crushing and concentrated blasting pile,but also the advantages of simple operation,safety and reliability,and greatly improve work efficiency.Figure [66] Table [14] Reference [89]...