[0006] ①, the size of the blasting electrode is large
[0007] Since the
plasma blasting
experimental system uses the instantaneous release of high-
voltage electric energy to generate an explosion, the insulation effect between the positive and negative electrodes needs to be very reliable at the blasting electrode where the explosion energy is released, otherwise "creeping" will occur during the plasma blasting process. "phenomenon, and cause the explosion energy to be unable to be released concentratedly at the
metal wire at the end of the electrode, thus affecting the blasting effect; and in the plasma blasting
experimental system, the currently used blasting electrode adopts the "center-circle" electrode arrangement In this way, the center of the blasting electrode is a copper rod with a
diameter of 3 mm, and the outer surface of the copper rod is wrapped with a
polyethylene insulating layer with a thickness of 4 mm, and a copper tube with a wall thickness of 2.5 mm is placed outside the
polyethylene insulating layer. At this time, the overall
diameter of the blasting electrode is It reached 16mm; when carrying out the blasting experiment, it is necessary to put the blasting electrode into the drilled hole of the rock and other brittle material specimens, so the
diameter of the drilled hole should be at least 17mm; The size of the specimen should also increase accordingly, otherwise the
geometric similarity parameters in the physical similarity experiment cannot be met, and the increase in the size of the specimen puts forward higher requirements for other related equipment in the experiment
[0008] ②. The preparation process of blasting electrodes is complex
[0009] During the plasma blasting experiment, it is necessary to coil a certain length of
metal wire into a mosquito-repellent coil shape, and then fix the two ends of the wire to the positive and negative poles of the blasting electrode respectively with solder; the central copper rod of the currently used blasting electrode is the positive pole, There is a
small hole at one end of the positive copper rod, and the external copper tube is the negative pole. When installing the
metal wire, first insert one end of the metal wire into the
small hole of the positive copper rod, and then connect the metal wire and the positive copper rod together by
soldering , and then coil the metal wire into the desired shape, and finally solder the other end of the wire to the surface of the negative copper tube, but it is very easy to touch the insulating layer between the positive and negative electrodes during the
soldering process, resulting in
insulation failure, and at the same time Due to the large volume and
smooth surface of the negative copper tube, it takes a long time to heat the metal wire and the negative copper tube together, which makes the whole operation process complicated and the success rate is very low
[0011] In the plasma blasting
experimental system, the blasting electrode should have the ability to be reused many times. After each blasting, it is only necessary to reinstall the metal wire between the positive and negative electrodes; however, in
actual use, each blasting will Cause certain damage to the insulating layer between the positive and negative electrodes, or cause local melting and deformation of the insulating layer during the
welding wire process, and once the insulating layer has a weak part, the insulating layer is easily broken down when the electrode discharges In this case, the
insulation layer can only be replaced; when the situation is serious, it may also cause deformation and damage to the positive copper rod in the center of the blasting electrode, which will lead to the scrapping of the entire blasting electrode; therefore, the currently used blasting electrode The
reuse rate is low, and the production cost of the blasting electrode is high, which makes the
material consumption and cost of the plasma blasting experiment high
[0012] ④, single blasting electrode function
[0013] In blasting
engineering, blasting is mainly carried out with columnar charges (the length of the charge coil is much larger than the diameter of the charge roll), while the metal wires of the blasting electrodes currently used are arranged in the form of coil wires. When performing blasting experiments, only spherical charges can be simulated. The explosion of the charge pack (the ratio of the length of the charge roll to the diameter of the charge roll is less than 3) in the borehole restricts the development of research to a certain extent