scholarly journals Damage Model and Numerical Experiment of High-Voltage Electro Pulse Boring in Granite

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 727 ◽  
Author(s):  
Changping Li ◽  
Longchen Duan ◽  
Songcheng Tan ◽  
Victor Chikhotkin ◽  
Wenpeng Fu
Keyword(s):  
Shock Wave ◽  
High Voltage ◽  
Geometric Model ◽  
Damage Model ◽  
Wave Model ◽  
Potential Method ◽  
Rock Breaking ◽  
Particle Flow Code ◽  
Rock Surface ◽  
Rock Breakage

High-voltage electro pulse boring (EPB) has the advantages of high rock-breaking efficiency and good wall quality, and is a new and efficient potential method of rock breaking. The EPB process is defined as random because it is affected by many factors. At present, there is no suitable physical and mathematical model to describe the process and results of rock breakage in EPB, and the conclusions reached regarding rock-breakage mechanisms are not uniform. In this study, a complete damage model of high voltage EPB in granite is established, which includes a shock wave model and a damage model of high voltage EPB in granite. The damage model is based on the Particle Flow Code two-dimensional program. Use of a damage model of EPB accommodates the complete process of high voltage EPB, from discharge to production of a shock wave, and so rock-breaking via electro pulse can be simulated and calculated. The time-varying waveforms of shock waves with different electrical parameters are simulated and calculated on the basis of the model. Different shock wave forms are loaded into the surface and internal rock in the damage geometric model of EPB granite. Then, the breakage process of the rock surface and internally, and the mechanism of rock breakage using EPB are analyzed. This study provides a scientific basis for the quantitative expression and prediction of rock fragmentation in EPB in order to improve the drilling efficiency and reduction of energy loss in the process of EPB.

scholarly journals An Electro Breakdown Damage Model for Granite and Simulation of Deep Drilling by High-Voltage Electropulse Boring

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Changping Li ◽  
Longchen Duan ◽  
Songcheng Tan ◽  
Victor Chikhotkin ◽  
Xiaohui Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Electric Field ◽  
High Voltage ◽  
Breakdown Strength ◽  
Damage Model ◽  
Wave Model ◽  
Confining Pressure ◽  
Rock Breaking ◽  
Particle Flow Code

Electropulse rock breaking has wide application prospects in hard rock drilling and ore breaking. At present, there are no suitable physical mathematical models that describe electropulse boring (EPB) processes under confining pressures. In this paper, a high-voltage electropulse breakdown damage model is established for granite, which includes three submodels. It considers electric field distortions inside the rock, and an electric field distribution coefficient is introduced in the electro-breakdown model. A shock-wave model is also constructed and solved. To simulate the heterogeneity of rocks, EPB rock breaking in deep environments is simulated using the two-dimensional Particle Flow Code (PFC2D) program. The solved shock wave is loaded into the model, and confining pressure is applied by the particle servo method. An artificial viscous boundary is used in the numerical simulation model. Using this approach, a complete numerical simulation of electropulse granite breaking is achieved. Breakdown strength and the influences of physical and mechanical parameters on it are also obtained. Time-varying waveforms of electrical parameters are obtained, and the effect of confining pressure on EPB is also described.

A shock wave model of unstable rocket combustors

AIAA Journal ◽  
1964 ◽  
Vol 2 (7) ◽  
pp. 1285-1296 ◽  
Author(s):  
L. CROCCO ◽  
W. A. SIRIGNANO
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Shock Wave Model

scholarly journals Shock-wave model of the earthquake and Poincaré quantum theorem give an insight into the aftershock physics.

2018 ◽  
Vol 62 ◽  
pp. 03006
Author(s):  
Vladimir Kuznetsov
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Particle Systems ◽  
Many Body ◽  
Initial State ◽  
Recurrence Theorem ◽  
Shock Wave Model ◽  
Quantum Phenomena ◽  
First Time ◽  
Insight Into

A fundamentally new model of aftershocks evident from the shock-wave model of the earthquake and Poincaré Recurrence Theorem [H. Poincare, Acta Mathematica 13, 1 (1890)] is proposed here. The authors (Recurrences in an isolated quantum many-body system, Science 2018) argue that the theorem should be formulated as “Complex systems return almost exactly into their initial state”. For the first time, this recurrence theorem has been demonstrated with complex quantum multi-particle systems. Our shock-wave model of an earthquake proceeds from the quantum entanglement of protons in hydrogen bonds of lithosphere material. Clearly aftershocks are quantum phenomena which mechanism follows the recurrence theorem.

scholarly journals Investigating the resetting of OSL signals in rock surfaces

2011 ◽  
Vol 38 (3) ◽  
pp. 249-258 ◽  
Author(s):  
Reza Sohbati ◽  
Andrew Murray ◽  
Mayank Jain ◽  
Jan-Pieter Buylaert ◽  
Kristina Thomsen
Keyword(s):  
Potential Method ◽  
Luminescence Dating ◽  
Rock Surface ◽  
Solar Simulator ◽  
Luminescence Signal ◽  
Thermal Transfer ◽  
Two Samples ◽  
Small Doses ◽  
Inner Parts ◽  
Partial Bleaching

Abstract There are many examples of buried rock surfaces whose age is of interest to geologists and archaeologists. Luminescence dating is a potential method which can be applied to dating such surfaces; as part of a research project which aims to develop such an approach, the degree of resetting of OSL signals in grains and slices from five different cobbles/boulders collected from a modern beach is investigated. All the rock surfaces are presumed to have been exposed to daylight for a prolonged period of time (weeks to years). Feldspar was identified as the preferred dosimeter because quartz extracts were insensitive. Dose recovery tests using solar simulator and IR diodes on both K-feldspar grains and solid slices taken from the inner parts of the rocks are discussed. Preheat plateau results using surface grains and slices show that significant thermal transfer in naturally bleached samples can be avoided by keeping preheat temperatures low. Equivalent doses from surface K-feldspar grains were highly scattered and much larger than expected (0.02 Gy to >100 Gy), while solid surface slices gave more reproducible small doses (mean = 0.17±0.02 Gy, n = 32). Neither crushing nor partial bleaching were found to be responsible for the large scattered doses from grains, nor did the inevitable contribution from Na-feldspar to the signal from solid slices explain the improved reproducibility in the slices. By modelling the increase of luminescence signal with distance into the rock surface, attenuation factors were derived for two samples. These indicate that, for instance, bleaching at a depth of 2 mm into these samples occurs at about ∼28% of the rate at the surface. We conclude that it should be possible to derive meaningful burial doses of >1 Gy from such cobbles; younger samples would probably require a correction for incomplete bleaching.

Experimental Study of Mechanism of Rock Breakage with High-Pressure Cavitating Water Jets

2011 ◽  
Vol 243-249 ◽  
pp. 2130-2137
Author(s):  
Zhao Long Ge ◽  
Yi Yu Lu ◽  
Ji Ren Tang ◽  
Ke Hu ◽  
Wen Feng Zhang
Keyword(s):  
High Pressure ◽  
Confining Pressure ◽  
Rock Breaking ◽  
Pressure Increase ◽  
Rock Breakage ◽  
Bubble Cloud ◽  
Cubic Curve ◽  
Water Jets ◽  
Erosion Efficiency ◽  
Pump Pressure

To explore the relationship among the erosion ability of high-pressure cavitating water jets, hydraulic parameters and rock nature with a series of experiments relating to the efficiency of rock-breaking with cavitating water jets for different porosity of rock under different confining pressures and pump pressures. The results show that the erosion efficiency (erosion mass and erosion depth) of cavitating water jets is fitted a conic curve with pump pressure and confining pressure. It increases with the pump pressure increases while decreases with the confining pressure increases; the length of the bubble cloud decreases with the confining pressure increase and the length increases with the pump pressure increase, which is accorded with cubic curve. The bubble cloud length influences the rock-breaking efficiency by deciding the valid stand-off distance directly. Under the experimental condition, the cavitation happens once the pump pressure reaches 7MPa, and the cavitating water jets can crushing the sandstones which the uniaxial compressive strength is 96MPa. On the other hand, the porosity of rock is another main factor of rock breakage with high pressure cavitating water jets. The higher the porosity of rock is, the easier the rock can be broken.

A periodic shock wave model for Mira variable atmospheres

1985 ◽  
Vol 299 ◽  
pp. 167 ◽  
Author(s):  
E. Bertschinger ◽  
R. A. Chevalier
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Mira Variable ◽  
Periodic Shock ◽  
Shock Wave Model ◽  
Periodic Shock Wave

The Formation of Chondrules: Petrologic Tests of the Shock Wave Model

Science ◽  
1998 ◽  
Vol 280 (5360) ◽  
pp. 62-67 ◽  
Author(s):  
H. C. Connolly Jr.
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Shock Wave Model

Damage Due to Cavitation and Sub-Cooled Boiling Bubble Collapse

1968 ◽  
Vol 183 (1) ◽  
pp. 31-50 ◽  
Author(s):  
F. G. Hammitt
Keyword(s):  
Shock Wave ◽  
High Velocity ◽  
Wave Model ◽  
Bubble Collapse ◽  
Spherical Shock Wave ◽  
Cavitation Damage ◽  
Present Evidence ◽  
Theoretical Evidence ◽  
Shock Wave Model ◽  
Spherical Shock

The possibility of the applicability of spherical symmetry to cavitation and highly sub-cooled bubble collapse is considered in the light of present photographic and theoretical evidence, and it is concluded that such symmetry is unlikely in situations of engineering importance. Rather an asymmetry which generates a high-velocity microjet is a more likely mode of collapse. The present evidence relative to the importance of microjet impact as opposed to the classical spherical shock-wave model for cavitation damage is examined and some new experimental evidence presented. It is concluded that the microjet model is most likely of predominant importance in cavitation damage. Some estimates for the pertinent parameters of such microjets are presented.

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