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By Jan Mehren, Arild Neby

Underwater Tunnel Piercing or Lake Tap, often also called the Norwegian Method, will in many projects be an important part of the hydro electric development scheme. The very last blasting round in the Lake Dorothy Lake Tap Tunnel, which penetrated into the lake at a depth of 120 ft (36 m), was such a key step in constructing the Lake Dorothy Hydroelectric Project. A lake tap project is multidisciplinary. Besides the pure blasting and construction technique aspect, engineering geological and geometric considerations that aim to optimize the tunnel alignment making a lake tap possible at minimized risk are of significant importance. Output data from numerical model analysis of the hydrodynamics resulting from the blasting is vital for the final adjustments to the geometrical layout. The planning of monitoring systems for the surveillance of hydrodynamic impact on valves and pipes as well as control with water levels and air pressures prior to and during the blasting, are all additional crucial elements in the design. More than 600 lake taps have been successfully performed in Norway since the 1890`s. The technique, which deserves to be called well proven, has been applied mostly in the hydropower sector but over the last 20 years also for shore approaches in the oil and gas industry. The demand for this technique seems to be ever more growing.

Jan 1, 2009

By Miquel Lamadrid, Changshow Sun, Chris Johnson

To reduce blasting overbreak and improve stope stability, several new blast designs were proposed for current and future stopes. Based on the analysis of the powder factor, and the extent of damage zone, the appropriate new blast design was selected. Excellent results were achieved from the new blast design. Comparing the new blast design with the old one, the largest of the overbreaks decreased more tan two times and average overbreak reduced more than two times. The new blast design is currently applied in all mining zones in Leeville underground mine.

Jan 1, 2008

By Joshua Hoffman, Braden Lusk, Perry Kyle

With the advent of any new technology comes the necessity of fully understanding the mechanics of that technology. The Shock Tunnel is one such technology that provides a cost effective means of simulating large-scale explosions while requiring a fraction of the explosive and space. Although the technique is known and practiced, the dynamics and mechanics of this technology has yet to be fully understood. A relationship between the energy potential of a given explosive and the energy realized at a set of distances was determined. This data was then compared to the energies realized from the same explosive when utilized in conjunction with a shock tunnel. A relationship between potential and realized energy outputs from explosive based shock tunnels exists and the understanding of this relationship would allow all for predictions to be made to forecast a specific amount of explosive required to produce a desired energy output. This energy output should then be relatable to peak pressures produced via the shock tunnel. Two shock tunnels are currently accessible for this study, the first under the direction of the University of Kentucky, and a second under the direction of the Missouri University of Science and Technology. The two shock tunnels differ in dimensions but share common construction materials. Energy realized from a shock tunnel is hypothesized to be a function of the shock tunnel’s dimensions. This study explores how different geometries affect the shock tunnel’s performance; this exploration is broken down into three phases. Phase 1: Open arena testing in which theoretical energies produced by the detonation of small (<1.0 kg) charges are compared to actual experimental values. Phase 2: Shock Tunnel testing in which realized energies are experimentally recorded for the UK shock tunnel. Phase 3: Analysis of the data to lay down the ground work for producing a pressure-forecasting tool given shock tunnel dimensions and explosive characteristics with the possible detection of avenues for optimization of shock tunnels.

Jan 1, 2009

By Francisco Sena Leite, Vinicius Miranda

Mine blasting is directly associated with ground vibration. If these affect critical structures (buildings pit walls, etc.) they must be mitigated to reduce the environment and social impacts. Vibration monitoring and control is one of the most important procedures in blasting because it will impact short and long term incidents associated with this blast effect. Technology moves ever forward, and today we have personal devices that are equipped with an array of sensors, for that reason the authors decided to investigate the possibility of using a personal device to do vibration control. This case study compares the same blast measured with a traditional seismograph and a smartphone. To validate this new methodology, attenuation laws were built with data from a traditional seismograph and a smartphone application. Predictions were also made prior to a set of blasts. Residual analysis was used for data validation from the two different sources. From the performed analysis, to prove the validity of this new methodology, the normality tests for statistics residues analysis proves that it is possible to infer that the model has a null residual mean and a small residual error. The achieved results show the accuracy of these devices, the authors pretend to show the potential of this equipment and open a completely new door for vibration analysis.

Jan 1, 2018

By M. Khaled, K. Abdel Rahman, M. Khattab

Helwan limestone quarry is located at a distance of 35 km (21.7 miles) to the south of Cairo downtown. Drilling and blasting operations are used to extract the limestone for the Helwan Cement Company (HCC). In 1980’s a new urban community was constructed adjacent to the quarry. This situation led to shifting of the old quarry 5.0 km (3.1 miles) to its current location, to avoid causing blasting problems to the new community. Unfortunately, the new quarry is opened in a highly faulted area, with weak zones of brittle materials. The drilling and blasting crew is facing many difficulties due to the geological complexity along these zones. Moreover, the extension of this community towards the new quarry makes the control of ground vibrations is very important.

Jan 1, 2008

By Kevin Phelps, Jason Baird, Philip Mulligan, Dominique Nolan

The basic metric for linear shaped charge performance is the amount of cutting distance that the charge can effectively yield given a specific standoff and target. Due to its size and restricted production runs the 10,500 grain/foot (2,232.25 grams/meter) linear shaped charge has had only limited studies that examine cutting performance and standoff. This article covers research regarding cutting performance verses standoff as the charge is applied to common structural steel. Specifically this study uses A36 mild carbon structural steel blocks of 10.16 cm by 11.80 cm by 35.56 cm and standoff distances of 0.5, 1.0, 1.5, and 2.0 charge diameters. Data presented includes the presentation of actual cutting performance numbers, comparison of that data to projected performance based on currently recognized industry guidelines, and a discussion of what may contribute to the performance found in this study.

Jan 1, 2013

By Jason Rock, Rob Thompson, Lee Julian

Reactive ground is ground that undergoes a spontaneous exothermic reaction after it comes into contact with nitrates. This is commonly caused by inert rock hosting sulphide minerals, such as pyrites that act as the reagent. The presence and subsequent rate of reaction with nitrate based bulk explosives can be difficult to predict. Once identified, only explosives that are tested and proven to be compatible with the reactive ground may only be used. These typically take the form of inhibited ammonium nitrate emulsion blended with a limited volume of ANFO or porous prilled ammonium nitrate (PPAN) to ensure that all AN prills in the blend are wholly encapsulated and thus protected from the reactive ground. The requirement for high emulsion content bulk products limits the suite of products available for use to high energy, and high expense products. Further, if chemically sensitised products are used, charged holes must be left unstemmed to allow for gassing to occur, adding delay and exposing the blast crew to an unconfined charge in reactive ground. A range of inhibited products has been developed that are solid sensitised and can be bulked to as low as 0.9 g/cc (56.2 lb/ft3). The use of a solid sensitiser enables stemming to occur immediately after each hole is charged, confining any unplanned detonation more safely within the rock mass. The effective and precise manufacture of bulked inhibited products required a new and innovative Mobile Processing Unit (MPU) design. This MPU required the ability to blend two solid raw materials (AN prill & sensitiser) along with two liquid ingredients (AN emulsion and process fuel). This MPU has been designed, manufactured and has used successfully to manufacture low density inhibited explosives. This paper presents an innovative shift in inhibited bulk products with specific reference to their manufacture and application.

By David Kosnik

This paper describes the technology and methods deployed in the continuous autonomous remote monitoring of cracks in interior and exterior walls of a residence near a limestone quarry. The objective is to quantitatively compare crack response due to blast-induced ground motion to that induced by diurnal temperature changes, weather fronts, occupant activity, and other phenomena. The remote monitoring and communication technology developed to obtain and disseminate crack response data for this study may provide the means to mitigate the effect of public concerns about potential impacts of ground vibrations inherent in construction and production of raw materials; it is critical to address these concerns because subsequent litigation may result in delays and increased costs.

Jan 1, 2009

By J T. Schamaun

Recent applications of explosives and blasting agents to rubble rock have led to requirements for more elaborate design and analysis methods. In most blasting uses, it is necessary not only to fracture the rock, but also to move the broken rubble in a predictable manner. Many in situ extraction techniques require; rubblization to take place in a confined region where rock motion is a predominate factor in creating a permeable broken bed. In this paper, an engineering model is presented which describes the large rubble motion during blasting. This model is intended to provide the blast designer with a tool for evaluation and further refinement of blasting patterns and timing sequences.

Jan 1, 1983

By Paul Worsey, Braden Lusk, Seokbin Lim

This paper discusses the theory and experiment involved in the discovery of the mechanisms of Linear Shaped Charges, which are much different from those for Conical Shaped Charges. Linear Shaped Charges (LSC) have been assumed to function in the same manner as Conical Shaped Charges (CSC) in the published literature on the subject. Much work has been done on CSC for military purposes, but there is limited information about the mechanics of LSC. Previous theories have cited the formation of a Monroe Jet as the dominant process. The Monroe Effect describes what happens to a target below the charge following detonation of the charge, and prescribes a fluid jet process for penetration. The fluid jet comprised of the liner material is the cutting device in CSC and has been extensively studied. Recent work at the University of Missouri at Rolla (UMR) cutting concrete with LSC has surprisingly shown that there is not a fluid jet process in LSC. After completing several reinforced concrete penetration tests, minimally deformed copper blades were found in the debris. Initially, the blades were suspected to be misfires or malfunctioned charge remnants. However, results were good and blades were found after every single test. Upon closer inspection, the ribbons were found to be folded copper and they were suspected to be the bottom liner of the LSC. A test series was conducted to verify the new theory by experiment.

Jan 1, 2005

By Terry Nichols, Karl E: Warkwick Burgher, Charles J. Wideman

The application of Fourier spectral analysis to records of ground vibration generated by over 100 explosions from an open pit mine is used to develop empirical predictor equations that relate the response spectra to the blasting parameters used to generate the excitation motion. Time series representations of ground particle velocity are transformed into the frequency domain where the appropriate modifications are made such that the inverse Fourier transform yields the time series representation of particle displacement and acceleration. Compensations are made for the transform function of the recording system in the frequency domain. Spectral analysis of the three types of ground motion is correlated with the blasting parameters. The results show that the frequency content of ground vibrations generated from a mine blast can be quantified in terms of the predictor equations.

Jan 1, 1990

By Frank Hirthammer

Over the past few years, development and implementation of digital logistics solutions has convinced users of many additional advantages of this technology. Barcode labeling and reading increases the company’s efficiency and safety by reducing handwritten documentation and preventing misinformation. Sustainable information and productivity management is a significant advantage in competition. Since manufacturing information is tracked throughout the whole supply chain until the final consumer, all processes become transparent what ensures efficient risk tracking, correct disclosure to authorities (if required), and the compliance with company rules.

Jan 1, 2018

By Thomas F. Mechtenberg, Michael S. Powell

In the past several years many coal operators and stone producers have reduced drilling and blasting cost by utilizing Bulk Emulsion/ANFO blends. For many operators the cost of equipment to handle blend products has been a major consideration in evaluating overall cost effectiveness of changing from packaged products or bulk ANFO to blends. This is especially true when the project length is short term or is uncertain.

Jan 1, 1990

By A. Torrance

A better understanding of the detonation performance of an explosive charge can be gained by directly measuring pressure, temperature and velocity of detonation (VOD). This is particularly important with commercial explosives because their performance is directly influenced by the degree of confinement given by the borehole diameter and the surrounding rock mass. A project funded by the Australian Coal Association Research Program (ACARP) was initiated in early 2009 with the view to design and build cost effective prototype instrumentation to measure the relative differences in detonation pressures and temperatures of commercial mining explosives. The project’s primary focus was on low density explosives. Low density (also referred to as low shock) explosives have been available in various forms for nearly 20 years. Identifying the pressure release patterns of both conventional and low density explosives under different geotechnical conditions should provide the necessary information to both validate detonation codes and better define input parameters for breakage and fragmentation models. This paper gives a general description of the prototype instrumentation developed and reports on the results obtained to date in testing the proposed instrumentation in laboratory scale conditions.

Jan 1, 2011

By Dworzak, Andrzej Biessikirski, Jozef Pyra

During the detonation process 20-30% of the energy is being consumed only on the quarrying pro-cess. The remaining amount of the energy generates harmful effects such as: shock wave, acoustic wave, fly rocks and ground vibrations. The ground vibrations effect is the most dangerous especially to structures which are situated nearby an open pit mine.

Jan 1, 2015

By Peter Duniam, Vivian Patz

History of the ExEx 1000 CAB system. l What we’ve learned using electronic timing. l Requirements for a second generation. EDD system. l The ExEx 2000 system - simple, versatile and cost effective

Jan 1, 1997

By K. Hausmann, W. Whelchel

The properties of ethylene Ionomer resins for the inner layer of non-electric shock tubes will be discussed in detail, and opportunities for property enhancement will be pointed out. A stiffness program for prediction of shock tube stiffness, as determined by the stiffness of the individual layers, will be presented and discussed.

Jan 1, 2010

By Robert B. Hopler

The history of bulk loaded explosives begins with the loading of black powder and RRP (Railroad Powder) into vertical boreholes. The early air place, net of black powder and nitrostarch dynamites is covered, as are the brands and formulas of the nitroglycerinsensitized "Bagged" powders.

Jan 1, 1993

By Zheng Deming, Li Hongwei, Lei Zhan, Dai Chunyang

This paper introduces the application of a digital electronic detonator in the demolition blasting of largescale (LS) and long delay time (LDT) frame-shear structure buildings. The whole building to be demolished by blasting is an L-shaped frame shearing structure. Some parts of these buildings have a large length along the direction of collapse, so the detonation delay of the column is longer. To ensure the building is successfully blasted and demolished, a digital electronic detonator detonation system is adopted. In the design of the detonating network, full use is made of these characteristics of the digital electronic detonator, such as flexible installation, high precision of delay before blast, and dedicated testing equipment to check the reliability of the network. These advantages ensure the damage of the load-bearing structure is within the blasting gap and that the accuracy of the collapse time of the building, which not only guarantees the collapse effect of the building, but also provides strong technical support for improving the intrinsic safety of the blasting operation and the supervision of the flow direction of the detonation, these research be provide reference for the application of digital electronic detonators in similar projects.

Jan 1, 2019

By Robert Slivinski, Kyle Hobbs, Michael Stern, John Willox, Brad Jewson

Prairie Mines & Royalty Ltd. produces over 12 million tonnes annually of thermal coal for TransAlta’s Sundance and Keephills power stations from the Highvale Mine. This opencast mine is next to a lake and is surrounded by cottages and farms, which means that blast vibrations and air overpressure have to be kept to a minimum.

Jan 1, 2008