scholarly journals Blast-Induced Damage on Millisecond Blasting Model Test with Multicircle Vertical Blastholes

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qin-yong Ma ◽  
Pu Yuan ◽  
Jing-shuang Zhang ◽  
Rui-qiu Ma ◽  
Bo Han
Keyword(s):  
Longitudinal Wave ◽  
Wave Velocity ◽  
Damage Zone ◽  
Damage Effect ◽  
Vertical Shaft ◽  
Longitudinal Wave Velocity ◽  
Damage Factor ◽  
Before And After ◽  
Cutting Effect ◽  
Concrete Model

To investigate the blast-induced damage effect on surrounding rock in vertical shaft excavation, 4 kinds of millisecond blasting model tests with three-circle blastholes were designed and carried out with excavation blasting in vertical shaft as the background. The longitudinal wave velocity on the side of concrete model was also measured before and after blasting. Then blast damage factor was then calculated by measuring longitudinal wave velocity before and after blasting. The test results show that the blast-induced damage factor attenuated gradually with the centre of three-circle blastholes as centre. With the threshold value of 0.19 for blast-induced damage factor, blast-induced damage zones for 4 kinds of model tests are described and there is an inverted cone blast-induced damage zone in concrete model. And analyses of cutting effect and blast-induced damage zone indicate that in order to minimize the blast-induced damage effect and ensure the cutting effect the reasonable blasting scheme for three-circle blastholes is the inner two-circle blastholes initiated simultaneously and the outer third circle blastholes initiated in a 25 ms delay.

Numerical Simulation of Blasting-Induced Damage in Grouting Curtain of Sandstone Aquifer for Vertical Shaft

2015 ◽  
Vol 723 ◽  
pp. 271-278
Author(s):  
Yu Liang Zhou ◽  
Dong Feng Yuan ◽  
Jun Zheng ◽  
Hua Wang
Keyword(s):  
Numerical Simulation ◽  
Prevention And Control ◽  
Damage Zone ◽  
Surrounding Rock ◽  
Damage Effect ◽  
Vertical Shaft ◽  
Control Methods ◽  
Sandstone Aquifer ◽  
And Control ◽  
Dynamic Damage

To provide a theoretical basis for water prevention and control methods and reasonable supporting techniques for vertical shaft, and to ensure the shaft construction to pass the sandstone aquifer safely and rapidly, numerical simulation using dynamic damage constitutive model, which was a user-defined constitutive modules in FLAC3D, a lagrangian analysis code in three dimensions, has been applied to investigate the dynamic damage effect in the surrounding rock of the grouting curtain near the driving working face for vertical shaft excavated by blasting. The results indicate that the distribution of the damage zone in the surrounding rock of the shaft, which decreases the effective thickness of the grouting curtain, was like a ellip-se, and that the depth of the damage zone in the surrounding rock of the shaft grouting curtain is fewer than that of the driving face floor. It can be concluded that the centre part of the driving face floor, especially the cutting hole zones, and the shaft wall in the greater horizontal stress side are the " key parts " for shaft water prevention and control methods.

Determining the Thermal Shock Elastic Behavior of Mullite Ceramic Regenerator Material by Ultrasonic Testing

2014 ◽  
Vol 633 ◽  
pp. 472-475 ◽  
Author(s):  
Tian Tian Sun ◽  
Yan Xia Wang ◽  
Hai Yun ◽  
Dong Huan Zhang ◽  
Qing Hui Shang
Keyword(s):  
Thermal Shock ◽  
Longitudinal Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Temperature Difference ◽  
Shear Wave Velocity ◽  
Modulus Of Elasticity ◽  
Longitudinal Wave Velocity ◽  
Mullite Ceramic ◽  
Mullite Ceramics

Mullite material is a material commonly used in honeycomb regenerator, because in the process of using material under big temperature difference effect, so have a great demand for its thermal shock resistance. The used mullite ceramics were made by the direct solid phase sintering method, and the modulus of elasticity of the mullite ceramics measured by ultrasonic pulse-echo method in a thermal shock and thermal fatigue experiment, respectively. In the air-cooling condition, the study found the mullite ceramic without thermal shock that the longitudinal wave velocity and shear wave velocity respectively 3970(m/s) and 2492(m/s). After 45 times thermal shock of temperature difference of 800°C, longitudinal wave velocity and shear wave velocity decreased to 3910(m/s) and 2457(m/s), and the value of the modulus of elasticity changed 1020MPa. By observing the change of the elastic modulus value rule, can know the elastic deformation of thermal shock on the material performance of thermal shock damage. Moreover, the results can provide the data basis for the calculation of the residual strength and the numerical simulation of thermal stress.

Ultrasonic Study on Crystal Orientation Effects Upon Point Defect Growth Caused by Cross Slip Under Plastic Deformation

2004 ◽  
Author(s):  
Michiaki Kobayashi
Keyword(s):  
Plastic Deformation ◽  
Longitudinal Wave ◽  
Wave Velocity ◽  
Crystal Orientation ◽  
Pure Shear ◽  
Cross Slip ◽  
Polished Surface ◽  
Longitudinal Wave Velocity ◽  
Velocity Change ◽  
Change Tendency

Concerned with the longitudinal wave velocity changes under plastic deformation in pure shear state, the experimental results of longitudinal wave velocity are categorized to two types: (i) simple decreasing change tendency at polished surface specimens, and (ii) chaotic change tendency at unpolished surface specimens. In the present paper, the effects of surface roughness and crystal orientation on the amount of cross slip under plastic deformation are studied via finite element polycrystal model (FEPM) from the viewpoint of longitudinal wave velocity change showing a sensitive response to the point defects caused by cross slip.

Monitoring of Longitudinal-Wave Velocity and Attenuation of SrTiO3at Low Temperatures Using Picosecond Ultrasound Spectroscopy

2012 ◽  
Vol 51 (7S) ◽  
pp. 07GA09 ◽  
Author(s):  
Akira Nagakubo ◽  
Akihiro Yamamoto ◽  
Kenichi Tanigaki ◽  
Hirotsugu Ogi ◽  
Nobutomo Nakamura ◽  
...  
Keyword(s):  
Longitudinal Wave ◽  
Wave Velocity ◽  
Low Temperatures ◽  
Longitudinal Wave Velocity
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