scholarly journals Effect of Initiation Location within Blasthole on Blast Vibration Field and Its Mechanism

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Qidong Gao ◽  
Wenbo Lu ◽  
Zhendong Leng ◽  
Zhaowei Yang ◽  
Yuzhu Zhang ◽  
...  
Keyword(s):  
Detonation Wave ◽  
Forward Direction ◽  
Phase Delay ◽  
Cylindrical Charge ◽  
Blast Vibration ◽  
Vibration Field ◽  
Delay Effects ◽  
Acting Mechanism ◽  
Experimental Approaches ◽  
Drill And Blast

In drill and blast, the explosive filled in each blasthole is cylindrically shaped and generally initiated by the detonator. Thus, the effect of the initiation location must be addressed, as it determines the detonation direction along the entire column explosive. In this paper, the effect of the initiation location on blast vibration field and its acting mechanism were comprehensively investigated through the theoretical, computational, and experimental approaches. The results indicate that the initiation location plays an important role in the blast vibration filed of the cylindrical charge. The underlying effect of the initiation location can be regarded as the combined results of the energy distribution and phase delay effects of the column explosive source. The behavior of the rock mass in the single-hole blasting experiment demonstrates that the explosion energy is preferentially transmitted to the forward direction of the detonation wave. The seed wave-based computation model verifies that owing to the phase delay effect, the blast vibration field of the cylindrical charge is not uniformly distributed and is strengthened at the forward direction of the detonation wave. The production blasting experiment indicates that the ground PPV under bottom initiation is 61.3%∼211.7% larger than that under top initiation. In addition, the effect of the initiation location is sensitive to the charge length L and the denotation velocity D. Meanwhile, the effect of the initiation location vanishes with distance. The present study provides valuable reference for understanding the effect of the initiation location on blast vibration in drill and blast.

Study on Vibration Displacement of Ground Building Caused by Construction of Shallowly Bored Tunnel with Drill and Blast Method

2013 ◽  
Vol 838-841 ◽  
pp. 1359-1362
Author(s):  
Xiao Jun Zhou ◽  
Qi Sheng ◽  
Rui Guo
Keyword(s):  
Differential Equation ◽  
Mathematical Expression ◽  
Horizontal Displacement ◽  
Surrounding Rock ◽  
Rock Blasting ◽  
Blast Vibration ◽  
Vibration Displacement ◽  
Mathematical Formula ◽  
Main Factors ◽  
Drill And Blast

A mathematical formula to calculate relative horizontal displacement of ground building due to blast vibration of surrounding rock for bored tunnel by drill and blast method is propounded on the basis of differential equation for dynamic vibration, and the mathematical expression is deduced by means of Laplace transforms. The main factors which influence the horizontal displacement of ground building subject to rock blasting are also discussed in the paper.

scholarly journals Execution of Safe Blasting Under Adverse Conditions of a Powerhouse Complex: A Revisit to Sardar Sarovar Project, India

2020 ◽  
Vol 2 (1) ◽  
pp. 56-67
Author(s):  
Govind Raj Adhikari ◽  
R. Balachander ◽  
A. I. Theresraj
Keyword(s):  
Case Studies ◽  
Draft Tube ◽  
Underground Excavations ◽  
Blast Vibration ◽  
Underground Powerhouse ◽  
Adverse Conditions ◽  
Overall Stability ◽  
Sardar Sarovar ◽  
Drill And Blast ◽  
Smooth Blasting

 When the excavation of the underground powerhouse of the Sardar Sarovar Project, India was nearly complete, cracks were observed on the upstream and downstream walls of the powerhouse, and the installed instrumentation readings sounded an alert for the instability of the powerhouse cavern that could possibly derail the project, further excavation in the powerhouse cavern was halted. After completing stabilisation measures, the remaining underground excavations by drill and blast method were to be completed. This paper revisits case studies of controlled blasting for the remaining excavations, namely a construction ramp, turbine pits, draft tube tunnels connecting the powerhouse, and the concrete plugs erected at the exit ends of the draft tube tunnels. To ensure overall stability around the excavations, blast vibration was controlled by planning the excavations in proper sequences. The damage outside the planned line of excavations was controlled by adopting modified line drilling/smooth blasting techniques. The details of the sequence of excavations, drilling and blasting parameters, compiled from previous publications, are presented in this paper. This paper also describes the reasons why concrete plugs were erected in the draft tube tunnels, the details of the concrete plugs, the optimised drilling and blasting procedure for safe removal of the plugs, and the method adopted to quantify the damage.

scholarly journals A theory of the dependence of the rate of detonation of solid explosives on the diameter of the charge

1947 ◽  
Vol 189 (1018) ◽  
pp. 415-426 ◽  
Keyword(s):  
Detonation Wave ◽  
Chemical Reaction ◽  
Cylindrical Charge ◽  
Solid Explosive ◽  
Metal Case ◽  
Rate Of Reaction ◽  
Velocity Of Detonation ◽  
Solid Explosives ◽  
Different Diameters

The velocity of a detonation wave, in a cylindrical charge of solid explosive, is shown to be dependent on the diameter of the charge, and the relation between the velocity and the diameter is calculated. It is shown that this effect depends upon the rate of the chemical reaction occurring in the front portions of the detonation wave, and that it is possible, therefore, to determine this rate of reaction by measuring the velocity of detonation in bare charges of different diameters. The effect of a metal case surrounding the charge is also briefly discussed.

On the Use of the WRF Model to Mitigate Tropospheric Phase Delay Effects in SAR Interferograms

2011 ◽  
Vol 49 (12) ◽  
pp. 4970-4976 ◽  
Author(s):  
G. Nico ◽  
R. Tome ◽  
J. Catalao ◽  
P. M. A. Miranda
Keyword(s):  
Wrf Model ◽  
Phase Delay ◽  
Delay Effects

Numerical Simulation on Detonation Process in Variable-Section Charge under Condition of End-Point Detonation Model

2015 ◽  
Vol 799-800 ◽  
pp. 728-733
Author(s):  
Jun Ting Yin ◽  
Gang Li
Keyword(s):  
Numerical Simulation ◽  
Detonation Wave ◽  
Structure Design ◽  
Practical Significance ◽  
Cylindrical Charge ◽  
Oblique Collision ◽  
End Point ◽  
Variable Section ◽  
Velocity Of Detonation ◽  
Detonation Process

when detonation wave is spreading in cylindrical charge which has a shell constraint, the border of the shell will reflect the detonation wave, reflection wave still has a strong influence on charge’s centerline. Compared with cylindrical charge, the influence of variable-section charge’s stack reflection wave on centerline is unsteady, relating to the gradual trends height of section area. On the condition of end-point detonation, doing the numerical simulation on detonation process of equal-section charge 、reduced-increased charge and increased-reduced charge, analyzing the pressure and velocity of detonation products on position of centerline, founding in the range of gradually decreasing section al, detonation wave through reflecting and then occur oblique collision that induce the pressure increasing rapidly. Doing the numerical simulation on variable-section charge’s detonation, promoting the understand of the reflection wave mechanism and the velocity of detonation product, this can be a practical significance to further improve the charge structure design and realize the efficient utilization of detonation energy.

scholarly journals Mathematical and Mechanical Analysis of the Effect of Detonator Location and Its Improvement in Bench Blasting

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qidong Gao ◽  
Zhendong Leng ◽  
Ruipeng Yang ◽  
Yaqiong Wang ◽  
Ming Chen ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Rock Mass ◽  
Stress Field ◽  
Detonation Wave ◽  
Mechanical Analysis ◽  
Surrounding Rock ◽  
Explosion Energy ◽  
Cylindrical Charge ◽  
Bench Blasting ◽  
The Cost

The outcome of bench blasting significantly affects the downstream operations in mining. In bench blasting, the explosives charged in blastholes are generally cylindrically shaped and fired by the in-hole detonator. As the detonator determines the propagation of the detonation wave in the cylindrical charge, the effect of detonator location can never be ignored. In this paper, the mathematics and mechanics of the effect of detonator location was analyzed from the view of the distribution of explosion energy and blast stress field of a cylindrical charge. Then, a field blasting experiment and two numerical simulations were conducted to further display its effect on blasting outcomes. At last, the appearance of oversize boulders and rock toes in bench blasting was discussed, and an improved scheme of the detonator location was proposed to cope with these problems. Results indicate that the in-hole detonator has the capacity of adjusting the spatial distribution of explosion energy and blast stress field in the surrounding rock mass. The traditional recommendation of the bottom detonator is not always right. The optimized detonator location in bench blasting is available by properly combining the merits of traditional detonator locations. This study is of interest to improve the efficiency and reduce the cost of mining.

Learned Placebo Effects in the Immune System

2014 ◽  
Vol 222 (3) ◽  
pp. 148-153 ◽  
Author(s):  
Sabine Vits ◽  
Manfred Schedlowski
Keyword(s):  
Nervous System ◽  
Immune System ◽  
Associative Learning ◽  
Placebo Response ◽  
Immunosuppressive Drug ◽  
Immune Functions ◽  
Placebo Effects ◽  
New Therapeutic Approaches ◽  
Biological Variables ◽  
Experimental Approaches

Associative learning processes are one of the major neuropsychological mechanisms steering the placebo response in different physiological systems and end organ functions. Learned placebo effects on immune functions are based on the bidirectional communication between the central nervous system (CNS) and the peripheral immune system. Based on this “hardware,” experimental evidence in animals and humans showed that humoral and cellular immune functions can be affected by behavioral conditioning processes. We will first highlight and summarize data documenting the variety of experimental approaches conditioning protocols employed, affecting different immunological functions by associative learning. Taking a well-established paradigm employing a conditioned taste aversion model in rats with the immunosuppressive drug cyclosporine A (CsA) as an unconditioned stimulus (US) as an example, we will then summarize the efferent and afferent communication pathways as well as central processes activated during a learned immunosuppression. In addition, the potential clinical relevance of learned placebo effects on the outcome of immune-related diseases has been demonstrated in a number of different clinical conditions in rodents. More importantly, the learned immunosuppression is not restricted to experimental animals but can be also induced in humans. These data so far show that (i) behavioral conditioned immunosuppression is not limited to a single event but can be reproduced over time, (ii) immunosuppression cannot be induced by mere expectation, (iii) psychological and biological variables can be identified as predictors for this learned immunosuppression. Together with experimental approaches employing a placebo-controlled dose reduction these data provide a basis for new therapeutic approaches to the treatment of diseases where a suppression of immune functions is required via modulation of nervous system-immune system communication by learned placebo effects.

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