scholarly journals Instantaneous Rock Blasting Wave and Its Microscopic Characteristics during Interaction with Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Shaoqin Huang ◽  
Lifeng Luan ◽  
Wanli Xing ◽  
Qunyi Liu
Keyword(s):  
Stress Wave ◽  
Dynamic Strain ◽  
Rock Blasting ◽  
Wave Zone ◽  
Compressive Stresses ◽  
Signal Characteristics ◽  
Concrete Damage ◽  
Blasting Test ◽  
Improved Technology ◽  
Blasting Wave

This paper uses improved technology for dynamic strain measurement to investigate the dynamic strain signals of blasting wave action tested in the range of 8–16 cm from the central blast. Based on the blasting mechanism and on the analysis of signal characteristics, blasting waves are recognized and divided into three zones, namely, shock wave zone, stress wave zone, and gas-expanding zone. This paper studies the relationships between stress, strain, and time of every zone. The tensile and compressive stresses of stress wave are considered. After the blasting test, four cracks from the borehole center toward the minimum burden appear at the model surface. The relationship between blasting wave and concrete damage is analyzed.

Research on Rock Mass Blasting of Weak Plane by High Dynamic Strain Test

2013 ◽  
Vol 868 ◽  
pp. 335-338 ◽  
Author(s):  
Zhen Fang Li ◽  
Hua Jun Xue ◽  
Jun Chen ◽  
Kang Liu ◽  
Tian Yu He
Keyword(s):  
Rock Mass ◽  
Stress Wave ◽  
Dynamic Strain ◽  
Joint Surface ◽  
Rock Blasting ◽  
Joint Rock Mass ◽  
High Dynamic ◽  
Weak Plane ◽  
The Impact ◽  
Joint Rock

when explosive blasts in the rock, the stress wave of impact produced appears all kinds of phenomena, such as reflection, refraction, and transmission in the process of transmission on the joint surface because of discontinuity, heterogeneity and anisotropy of rock mass of weak plane in physics, which lead to extremely complex on rock blasting process. Through conducting on high dynamic strain test of blasting process on joint rock mass model, it researches dynamic load characteristics of joint rock mass and joint-planes effect on extension of critical raw crack and attenuation law of stress wave, analyzes the strain waveform of strain gages which locate in the different direction between initial crack of blasting and joint, and figures out the impact of joint plane on the stress wave transmission, which provide an important theoretical basis on the relevant parameters design in the process of blasting engineering of joint mass existing in actual.

scholarly journals Effect of Adjacent Hole on the Blast-Induced Stress Concentration in Rock Blasting

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yuezong Yang ◽  
Zhushan Shao ◽  
Junfeng Mi ◽  
Xiaofeng Xiong
Keyword(s):  
Stress Concentration ◽  
Stress Wave ◽  
Surface Effect ◽  
Material Model ◽  
Major Effect ◽  
Hole Diameter ◽  
Rock Blasting ◽  
Induced Stress ◽  
Hole Wall ◽  
Hole Effect

To investigate the effect of an adjacent hole on the blast-induced stress concentration in rock blasting, a rock blasting model with an adjacent hole is explored through theoretical analysis and numerical simulation. The commercial software LS-DYNA is utilized to simulate adjacent hole effect in rock blasting, in which the Johnson–Holmquist concrete material model is used to simulate rock and the high-explosive-burn-explosive and the equation of state of JWL are used to simulate explosive. Influences of the key parameters of adjacent hole effect in rock blasting, pitch of holes, adjacent hole diameter, and uncoupled medium in a blasting hole are extensively explored. According to the simulation results, when the explosion stress wave spreads to the adjacent hole wall, the tangential stress on the adjacent hole wall induced by the explosion stress wave is always greater than the radial stress. Adjacent hole diameter has a major effect on stress concentration, but with the adjacent hole diameter increasing, the stress concentration phenomenon weakens and the free surface effect of the adjacent hole plays a more important role.

scholarly journals Fracture Initiation, Gas Ejection, and Strain Waves Measured on Specimen Surfaces in Model Rock Blasting

2020 ◽  
Author(s):  
Zong-Xian Zhang ◽  
Li Yuan Chi ◽  
Yang Qiao ◽  
De-Feng Hou
Keyword(s):  
High Speed ◽  
Fracture Initiation ◽  
Dynamic Strain ◽  
High Speed Photography ◽  
Surface Cracks ◽  
Rock Blasting ◽  
Measured Velocity ◽  
Strain Waves ◽  
Gas Penetration ◽  
Radial Cracks

AbstractCrack velocity, gas ejection, and stress waves play an important role in determining delay time, designing a blast and understanding the mechanism of rock fragmentation by blasting. In this paper, the emerging times of the earliest cracks and gas ejection on the lateral surfaces of cylindrical granite specimens with a diameter of 240 mm and a length of 300 mm were determined by high-speed photography, and the strain waves measured by an instrument of dynamic strain measurement during model blasting. The results showed that: (1) the measured velocity of gas penetration into the radial cracks was in a range of 196–279 m/s; (2) the measured velocity of a radial crack extending from the blasthole to the specimen surface varied from 489 to 652 m/s; (3) the length of strain waves measured was about 2800 µs, which is approximately 1000 times greater than the detonation time. At about 2850 µs after detonation was initiated, gases were still ejected from the surface cracks, and the specimens still stood at their initial places, although surface cracks had opened widely.

Propagation Character of the Stress Wave in Weld Joints

2011 ◽  
Vol 199-200 ◽  
pp. 801-804 ◽  
Author(s):  
Hong Wei Song ◽  
Zhen Luo ◽  
San San Ao ◽  
Rui Wang
Keyword(s):  
Stress Wave ◽  
Large Scale ◽  
Low Cost ◽  
Dynamic Strain ◽  
Stress Wave Propagation ◽  
Long Distance ◽  
Test Technique ◽  
Butt Weld ◽  
Weld Joints ◽  
Before And After

Stress wave test technique has broad prospects because of the long distance, large scale and relatively low cost. This paper studies the stress wave propagation characteristics in the butt weld joints in the case of external symmetrical impact. The stress wave propagating before and after the joints is measured by dynamic strain gauge. Then model analysis and simulation is applied to research stress wave. The results show the loss of stress wave is small. After spectrum analysis, the change of propagating stress wave can be detected.

scholarly journals A Method for Making Transparent Hard Rock-Like Material and Its Application

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Jinjin Ge ◽  
Ying Xu
Keyword(s):  
Model Experiment ◽  
Hard Rock ◽  
Cement Mortar ◽  
Physical And Mechanical Properties ◽  
Model Material ◽  
Rock Blasting ◽  
Similar Model ◽  
Similar Material ◽  
Deep Rock ◽  
Blasting Test

At present, a similar material most commonly used in the similarity model experiment of rock blasting is cement mortar. However, it is not transparent, which leads to the problem that the cracks in the model made of cement mortar after the test cannot be observed directly. Therefore, a kind of transparent hard rock-like material that can replace the existing model material to solve the above problem was developed in this study. This transparent hard rock-like material is made of a mixture of rosin saturated solution (RSS), epoxy resin (ER), and curing agent (CA), and its physical and mechanical properties are similar to those of hard rock through relevant tests. In addition, it is found through the blasting model test that the model specimen made of transparent hard rock-like materials has the characteristic of “direct observation” after blasting test, which conforms to the rock blasting fracture mechanism. Hence, it can replace the existing nontransparent model materials to be applied in rock blasting similar model experiment. The results from this study are helpful to the further experimental study of blasting crack propagation in deep rock mass.

Numerical Simulation Research on Single Hole_unilateral Protecting Borehole Wall Blasting

2011 ◽  
Vol 368-373 ◽  
pp. 395-398
Author(s):  
Liang Niu ◽  
Zhi Cheng Zhang ◽  
Xiao Ling Liu ◽  
Jun Lin Tao ◽  
Yong Gang Lu
Keyword(s):  
Numerical Simulation ◽  
Stress Wave ◽  
Blast Hole ◽  
Borehole Wall ◽  
Rock Blasting ◽  
Pressure Relief ◽  
Simulation Research ◽  
Hole Wall ◽  
Material Substance

3-D Numerical simulation on the directional pressure relief partition side of blast hole isolation material though LS-DYNA software. The result shows: the semicircle isolation material can put off the time that the explosion stress wave arrived at the hole-wall and reduce the peak of stress wave. Meanwhile, it proves that the explosion in the material substance is more powerful than that in the air. So it has certain directive significance on rock blasting on the slope.

Experiment on Different Length/Diameter Ratio Charge Explosive Strain Wave Propagation in Rock

2012 ◽  
Vol 170-173 ◽  
pp. 343-347
Author(s):  
Ren Shu Yang ◽  
Xiang Tao Gao ◽  
Yu Long Che
Keyword(s):  
Diameter Ratio ◽  
Energy Utilization ◽  
Relative Distance ◽  
Dynamic Strain ◽  
Testing System ◽  
Peak Strain ◽  
Rock Blasting ◽  
Strain Wave ◽  
Strain Testing ◽  
Relationship Of

In order to explore the blasting effect with charged by different length/diameter ratio in rock, adopted ultra-dynamic strain testing system to test the blasting strain wave with charged by little amount of explosives and different length/diameter in the rock models. Analyzed the radial blasting strain wave signal in the medium under the conditions of coupling charging explosive loading, got the generalities and difference of the explosive strain waveform features with charged by different length/diameter ratio, and relationship of peak strain with the relative distance. The results show that peak strain was greatly affected by the change of length/diameter ratio and charge mass in the area of close blasting source, when the relative distance is more than 45, the influence is less. Made the length/diameter ratio is 20 to be the boundary, when the length/diameter ratio is greater than 20, the peak strain attenuated slowly. The explosive energy of the big length/diameter ratio is relatively decentralized to the medium, improved the energy utilization ratio of explosives. The measured results provided a new experimental basis to further understand correctly the rock blasting mechanism.

Research on the Law of Propagation and Attenuation of the Explosive Stress Wave in Surrounding Rocks at Different Levels

2015 ◽  
Vol 723 ◽  
pp. 279-284 ◽  
Author(s):  
Yong Ye ◽  
Shan Qi Liu
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Stress Wave ◽  
Nonlinear Finite Element ◽  
Rock Blasting ◽  
Analysis Software ◽  
Element Analysis ◽  
Practical Engineering ◽  
Technical Guidance ◽  
Different Levels

By using nonlinear finite element analysis software-ANSYS/LS-DYNA, a numerical model was carried out to simulate the explosive stress wave generated from a single-hole coupling continuous charge blasting which varies with time at different levels of rock. Meanwhile, the propagation and attenuation law of the explosive stress wave at different rock levels was analyzed to gain an in-depth knowledge of rock explosion. The result shows that the explosive stress wave in rock is in the trend of exponential decay and presents three forms: shock wave, stess wave and seismic wave. It illustrates that numerical simulation can objectively reflect the failure law of rock blasting and provide theoretical and technical guidance for the corresponding practical engineering.

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