scholarly journals Study on Eccentric Uncoupled Blasting Effect of Cutting Seam Pipe

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 104
Author(s):  
Wei Wang ◽  
Jiaqi Zhang ◽  
Ao Liu
Keyword(s):  
Rock Mass ◽  
Working Conditions ◽  
Load Distribution ◽  
Growth Process ◽  
Peak Pressure ◽  
Initial Crack ◽  
Peak Time ◽  
Detonation Products ◽  
Side Rock ◽  
Guiding Effect

In order to study the blasting effect and the damage to the rock mass when the cutting seam cartridge is eccentrically and uncoupled. The ANSYS/LS-DYNA® nonlinear dynamic platform was used to simulate the blasting effect of five eccentric uncoupled coefficients on the cutting seam cartridge, and the crack growth process under the condition of complete eccentricity was simulated. By comparing and analyzing the stress of measuring points in the direction of cutting seam, vertical cutting seam direction, and circumferential cutting seam pipe under different working conditions. It is concluded that the effect of detonation products is affected by the wrapping property of the cutting seam pipe and the eccentric uncoupled coefficient. With the increase of the eccentric uncoupled coefficient, the load distribution presents obvious non-uniformity. The pressure on the uncoupled side of the blasthole is smaller than that on the coupled side, and the peak time of the uncoupled side also lags behind that on the coupled side. When the eccentric uncoupled coefficient is 1, the peak pressure on the coupled side is 5.78 times that of the uncoupled side, and the explosive stress field is biased toward the coupled side. The existence of the cutting seam pipe causes stress concentration at the opening, which enhances the guiding effect of the initial crack, and the stress in the non-cutting seam direction is buffered. Therefore, the eccentric arrangement of the cutting seam pipe determines the formation of the initial crack and the subsequent blasting effect. When the cutting seam cartridge is arranged eccentrically and uncoupled, it will cause under-excavation at the connection direction of blasthole, which will cause less disturbance to the rock mass on the uncoupled side. If the retaining side rock mass is on the coupled side in actual blasting, the eccentric uncoupled arrangement will cause greater over-excavation and damage. Therefore, it is necessary to avoid this situation as far as possible and provide better guidance for the actual construction.

On the Theory of the Calculation of the Constant Velocity Ball Transmission Joints

1976 ◽  
Vol 98 (3) ◽  
pp. 852-857 ◽  
Author(s):  
N. Bellomo
Keyword(s):  
Working Conditions ◽  
Load Distribution ◽  
Constant Velocity ◽  
Numerical Calculations ◽  
Torque Capacity ◽  
Safe Working ◽  
General Method

In this work a general method for the calculation of constant velocity ball transmission joint with straight grooves is studied. Numerical calculations concerning the forces transmitted by each driving ball and the torque capacity have been realized with reference to known and manufactured types of joint. The study allows one to deduce some important and experimentally confirmed designing rules and gives a precise picture of the load distribution in the joint as well as the limits of safe working conditions.

Seepage Stability Analysis for Surrounding Rock Mass of Diversion Tunnel by FEM

2013 ◽  
Vol 787 ◽  
pp. 622-625
Author(s):  
Yun Feng Xu ◽  
Zhen Zhong Shen ◽  
Chao Xin Shao
Keyword(s):  
Finite Element Method ◽  
Rock Mass ◽  
Working Conditions ◽  
Cross Sections ◽  
Surrounding Rock ◽  
The Other ◽  
Seepage Field ◽  
Diversion Tunnel ◽  
Pressure Method ◽  
Seepage Model

Based on the actual conditions of the project and related experience, the seepage model of diversion tunnel and its surrounding rock mass was built to analyze its seepage stability. The seepage field was calculated by using finite element method (FEM) and cut-off negative pressure method. Two typical cross-sections and working conditions were chosen to evaluate the seepage stability of the surrounding rock mass. According to the results, the seepage gradient is larger when one tunnel is filled with water while the other is empty. The maximum seepage gradient is less than the allowable seepage gradient, so the surrounding rock mass of the diversion tunnel can meet the demand of seepage stability.

scholarly journals The Change of the Spatial Parameters of the Destruction of the Rock mass by Borehole Charge with Low-Density Tamping

2018 ◽  
Vol 41 ◽  
pp. 01018
Author(s):  
Igor Katanov
Keyword(s):  
Rock Mass ◽  
Mass Velocity ◽  
Specific Impulse ◽  
Low Density ◽  
Detonation Products ◽  
Impact Time ◽  
Borehole Charge ◽  
Theoretical Reasoning ◽  
Spatial Parameters ◽  
The Impact

Explosive destruction of the rock formation is substantiated by several theories developed by well-known scientists. The improvement of quality of preparation of rock mass to excavation, by an excavator without an increase in the value of specific consumption of explosives is important in the present time. Traditionally, to increase the impact time of detonation products on the rock hard tamping was used. The problem is in the rational redistribution of the explosion energy due to the use of a borehole charge, and in particular, in the tamping of low-density, porous materials. The more intensive attenuation of the mass velocity of particles in the material of such tamping in comparison with the mass velocity of the rock mass particles contributes to the well channel compression and increases the impact time of detonation products on the rock mass. As a result of redistribution of energy of detonation products, the specific impulse of explosion increases. The value of the radius of the controlled crushing zone increases by more than 1.6 times. The results of industrial explosions in coal mines have confirmed the theoretical reasoning.

scholarly journals Rock Fracturing under Pulsed Discharge Homenergic Water Shock Waves with Variable Characteristics and Combination Forms

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Decun Bian ◽  
Jinchang Zhao ◽  
Shaoqing Niu ◽  
Jinwen Wu
Keyword(s):  
Numerical Simulation ◽  
Hydrostatic Pressure ◽  
Shock Waves ◽  
Crack Propagation ◽  
Peak Pressure ◽  
Initial Crack ◽  
Pulsed Discharge ◽  
Single Impact ◽  
Repeated Impacts ◽  
Different Characteristics

High voltage pulsed discharge in water (HVPD) is used throughout industry for fracturing both natural and man-made materials. Using HVPD, we modeled crack propagation of rocks under homenergic water shock waves (HWSW) with different characteristics and combination forms using a combination of experimental analysis and numerical simulation. The experimental results show that, under the same discharge energy (2 kJ), water shock waves (WSW) with different characteristics fractured the rock mass distinctly different. With a higher the peak pressure (PP) of WSW, more long cracks and microcracks were formed, creating a larger damage area. The numerical simulation results show that a single HWSWs impact with different characteristics will still only cause three long cracks to be well developed and almost no microcracks, when PP of HWSW was 3 MPa. With the increase of PP, the number of both long cracks and microcracks increased. This is consistent with the experimental results. When the peak pressure became greater than 15 MPa, crack propagation gradually became concentrated and the surrounding borehole wall became more severely broken. The rock model had optimal fracturing under the impact of the HWSW with a PP of 10 MPa. Also, the simulations showed that, under repeated-impacts of HWSWs with consistent characteristics, the fracturing characteristics were basically identical to those by a single-impact. While under the repeated-impact of HWSWs with variable characteristics, there was almost no relationship between the fracturing effect and the sequence of repeated-impacts. Finally, under a single-impact of HWSW with low PP and hydrostatic pressure (PH) acting within an initial crack (similar to hydraulic fracturing in a hydrocarbon well), the initial crack had excellent propagation with an increase in hydrostatic pressure. However, when PP of HWSW was too high, increasing PH had no effect on initial crack propagation.

Pressure Distribution under Symptom-Free Feet during Barefoot Standing

Foot & Ankle ◽  
1987 ◽  
Vol 7 (5) ◽  
pp. 262-278 ◽  
Author(s):  
Peter R. Cavanagh ◽  
Mary M. Rodgers ◽  
Akira liboshi
Keyword(s):  
Body Weight ◽  
Pressure Distribution ◽  
Significant Relationship ◽  
Plantar Pressure ◽  
Load Distribution ◽  
Peak Pressure ◽  
Distribution Analysis ◽  
Pressure Distributions ◽  
Transverse Arch ◽  
Peak Pressures

The plantar pressure distributions for a large heterogeneous sample of feet (N = 107) were collected during barefoot standing using a capacitance mat. From these data, the function of the foot during standing was characterized. Peak pressures under the heel (139 kPa) were, on average, 2.6 times greater than forefoot pressures (53 kPa). Forefoot peak pressures were usually located under the second or third metatarsal heads. No significant relationship was found between body weight and the magnitude of peak pressure. The concepts of a transverse arch at the level of the metatarsal heads and a “tripod” theory of load distribution were not substantiated by this study. Load distribution analysis showed that the heel carried 60%, the midfoot 8%, and the forefoot 28% of the weightbearing load. The toes were only minimally involved in the weightbearing process. Examples of unusual distributions are shown; finally, a checklist is provided to aid the clinician in evaluating plantar pressure findings.

Numerical Simulation of Thermobaric Explosive Explosion in Free Field

2014 ◽  
Vol 687-691 ◽  
pp. 696-700
Author(s):  
Xi Li ◽  
Bo Liang Wang ◽  
Zao Han ◽  
Ning Ning Zhao
Keyword(s):  
Numerical Simulation ◽  
Open Space ◽  
Peak Pressure ◽  
Free Field ◽  
Field Performance ◽  
Simulation Method ◽  
Blast Waves ◽  
Detonation Waves ◽  
Experiment Data ◽  
Detonation Products

In order to analyze the explosion characteristics on the free field performance of thermobaric explosive, parameters of blast waves produced by the investigated charges in an open space were measured by the use of piezoelectric sensors and the results were compared to traditional TNT. Moreover, a numerical simulation of TBE explosion in free field was performed within the frame of AUTODYN. Comparison with TNT reveals that the values of peak pressure and impulse of TBE are higher than that of TNT due to the secondary reaction of Al and detonation products. It is found that the simulation results of TBE detonation blast wave parameters coincided very well with the experiment data. This demonstrates that the simulation method used is an effective way to depict the spreading of detonation waves in free field for TBE.

Research of Influence Factors of Initial Crack with Slotted Charge Blasting

2010 ◽  
Vol 143-144 ◽  
pp. 797-801
Author(s):  
Guo Liang Yang ◽  
Ren Shu Yang ◽  
Chuan Huo ◽  
C.C. Pan
Keyword(s):  
Peak Pressure ◽  
Influence Factors ◽  
Initial Crack ◽  
Energy Propagation ◽  
Damage Area ◽  
Initial Damage ◽  
Pressure Peak ◽  
Simulation Results ◽  
And Function ◽  
Function Time

By numerical simulation, the researches of effecting initial crack forming with slotted charge blasting are performed. The effecting factories conclude radial uncoupled parameter α and seam width W. Herein α adopts 1.43, 1.67 and 2, and 4, 6, 8 and 10 are adopted by W separately. The pressure peak is 15.5 GPa under α=1.67, and formed long cracks. With 6 and 8 mm seam widths, energy focus phenomenon is remarkable. The results show that initial damage of rock are decided by peak pressure of gas and function time. The seam width has significant effect to initial damage. With W adopting 6 and 8 mm, effective energy propagation is ensured and excessive damage area is avoided. The experiments validate the simulation results.

scholarly journals Modelling the influence of gaseous products of explosive detonation on the processes of crack treatment while rock blasting

2021 ◽  
Vol 15 (3) ◽  
pp. 102-107
Author(s):  
Viktoriia Kulynych ◽  
Valerii Chebenko ◽  
Ruslan Puzyr ◽  
Iryna Pieieva
Keyword(s):  
Rock Mass ◽  
Building Materials ◽  
Strength Properties ◽  
Solid Particles ◽  
Lead Azide ◽  
Rock Fragment ◽  
Rock Blasting ◽  
Detonation Products ◽  
Gaseous Products ◽  
Explosive Detonation

Purpose is mathematical modeling of fracturing as well as influence of gaseous products of explosive detonation on the changes in rock strength. Methods. Mathematical model, using foundations of Griffith theory, has been developed. To explain conditions of bridge formation while exploding lead azide charges, a two-stage description of solid particle condensation at a crack surface and inside it has been applied using the smoothed particle hydrodynamics. The analysis, involved electronic microscope, has helped verified the results experimentally. Findings. The effect of rock mass disturbance, resulting from explosive destruction, is manifested maximally right after the action. Subsequently, it decreases owing to the gradual relaxation of the formed defects. Therefore, an urgent problem is to develop ways slowing down strength restore of the blasted rock mass fragments. The process of rock fragment strength restoring may be prevented by microparticles getting into the microcrack cavities together with the detonation products. The research simulates their action. The data correlate to the simulation results confirming potential influence of the blasted rock on the dynamics of changes in the strength characteristics of the rock mass. Various compositions of charges with shells made of inert solid additions have been applied which solid particles can avoid the process of microcrack closure. Originality. For the first time, the possibility of deposition formation within rock micro- and macrocracks has been proposed and supported mathematically. Practical implications. Strength properties of the finished product and the energy consumption during impulse loading as well as subsequent mechanical processing of nonmetallic building materials depend on the strength properties of rock mass fragments. Hence, the ability to control the strength restore has a great practical value. Moreover, it can be implemented during the blasting operations.

Improvement Effect of Discharge Circuit for the Underwater Shock Wave

2013 ◽  
Vol 767 ◽  
pp. 199-204 ◽  
Author(s):  
Osamu Higa ◽  
Takumi Matsui ◽  
Ryo Matsubara ◽  
Katsuya Higa ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
Peak Pressure ◽  
Discharge Circuit ◽  
Peak Time ◽  
Underwater Shock Wave ◽  
Improvement Effect ◽  
Underwater Shock

The purpose of this research is to examine the improvement effect of discharge circuit impedances. In this research, we decreased the inductive impedance of discharge circuit, and shorted the current peak time, and increased the current peak as well. As a result, the peak pressure increased to 135 %.

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