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By W. J. Birch, R. Farnfield

All shock-tube based initiation systems have a time lag relating to the propagation velocity of the shock-tube itself. This paper examines the exploitation of this inherent time lag to achieve delay blasting with accuracies approaching that achievable with electronic systems albeit over a much shorter delay range. The system employed consists of a combination of standard shock-tube, plain detonators and various shock-tube branching components. The accuracy of the complete system depends on the scatter in delay time induced by each component. In order to quantify this scatter a series of trials were undertaken to determine the variability for each component. These trials are described along with a detail statistical summary of the data recorded.

Jan 1, 2009

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 Jennifer Paukula, Steven Lindsay, S. Joon Kim

String loading is the placement of a bead or ‘string’ of emulsion along the lower edge of a development drill hole. The loading hose extraction rate controls the amount of emulsion placed in each drill hole. This allows a controlled distribution of explosive energy throughout the development round. Center holes are loaded using the slowest extraction rate causing the majority of the explosive energy to be placed in the center of the round. The loading hose is extracted successively faster for the buffer and perimeter holes causing less explosive energy to be placed near the edge of the blast. This causes less damage to the rock mass that remains in place after the development blast.

Jan 1, 2012

By Kahmmelly Mathildes Pimenta Coelho, Felipe Dantas, Jaine Ribeiro de Souza, Augusto Ferraz, Carlos Roberto Campos Junior, Davi Bastos Martins de Oliveira

The Carajás Iron Mine, recognized as the largest iron ore province in the world, is notable for its continuous efforts to improve operational efficiency and safety. In response to these objectives, a QA/QC (Quality Assurance and Quality Control) Program was implemented and integrated with Blastscout Probe technology to optimize drilling and blasting processes. The program supports the standardization of operational parameters, the execution of regular audits, and real-time data analysis, facilitating precise and timely adjustments. The implementation led to significant improvements, including an 80% increase in operational compliance, a 49% reduction in drilling depth deviations, and a 30% enhancement in Jaspelite fragmentation. This study presents the methodology employed, the outcomes obtained, and the positive impacts observed in both operational performance and environmental management.

Jan 26, 2026

By Paul Ross, Harry Burchett, Lou Case, Calvin J. Konya

"The Cumberland River in Harlan, Kentucky has flooded the town for numerous years. TheU.S. Army Corps of Engineers funded a project to divert the river. The project consisted oftunneling through a mountain to divert the river. The approaches to the tunnels requiredcontrolled blasting to create noses to help channel the water and debris into the tunnels.The geologic structure was such that conventional presplitting techniques were notproducing the desired results and were causing severe backbreak. Replacement of the rocknoses with concrete would cost about a million dollars; and therefore it was important tosave them if at all possible. Blasting techniques were developed which allowed the projectto be successfully completed. This paper will discuss the case history of the controlledblasting procedures."

Jan 1, 1993

By Justus Deen, Paul Sterk

Overbreak into the wall rock of a development drift leads to the inevitable need to rehabilitate a drift. Moreover, overbreak in a production heading can lead to external dilution and lower ore grades. Both of these factors are critical to bottom line costs of underground operations today. The geology of the Homestake orebody makes this an even more complex problem. For over fifteen years the Homestake Mine has attempted to implement perimeter blasting techniques that are both safe and cost effective. Many practical perimeter methods and products have been tested including air decking; low density emulsions; various types of stick powder; various decoupling media including rope, low density ANFO, polystyrene ANFO, salt based ANFO, and various grain detonating cords up to 200 grain.

Jan 1, 1997

By S. J. Dillingham

One of the primary goals of every blaster is to achieve the optimum blast design. Too much focus on efficient design, however, can cloud certain issues and exposures that must be addressed if the entire project is to be considered .successful.. Due to the known human response to blast effects and inherent dangers present in the use of explosives, the potential for the project being delayed or shutdown, or the blaster and associated company being named as a defendant in a lawsuit, is always a possibility. Therefore, the blast design and associated project bid must incorporate sound safety contingences and procedures that address those .what-if. Scenarios that may arise as a result of vibration, flyrock, public relations, and job-site personal safety.

Jan 1, 2002

In situ, most Taconite is heavily pre-fractured; because of the high cost of comminution of taconite, maximum fracture of pre-existing blocks is desirable. Sustained borehole pressure plays a significant role in fragmentation, especially by penetrating pre-existing fractures. The distribution of explosive-induced energy in the burden in three dimensions was calculated. Data on the comminution of single particles was used, with the distribution of energies and the distribution of pre-existing block sizes, to calculate fragmentation for a case study. The calculation agreed well with the measured fragmentation. Sequential comminution events are much more efficient than single ones, and enhanced fragmentation may be possible with alternative blasting practices. Some important factors in the dependence of comminution on energy input are discussed.

Jan 1, 1995

This paper presents a brief discussion of three case histories to illustrate several aspects of the question of blasting in or immediately adjacent to concrete. The results demonstrate a need to make dramatic upward revisions in previous criteria, whether it be the standard particle velocity criteria or damage response spectra bounds, - especially those which include conservative upper limits of constant acceleration for the high-frequency portion of the spectrum. It is demonstrated, also, that conventional off-the-shelf blast-monitoring instruments are not capable of monitoring small blasts at close range. Both the frequencies and the levels of effect are beyond the range of such instruments. These case histories suggest further that there is a need to review the applicability of certain wellknown equations of elasticity.

Jan 1, 1980

By Harry Verakis, Thomas Lobb

A great deal of information has been presented and published on the danger from flyrock created from blasting operations. The creation of flyrock is not specific to any one blasting operation. Flyrock is certainly not a stranger to blasting operations conducted in the mining industry and its effects are well known. Flyrock is among the leading causes of mine blasting injuries. Awareness and diligence is the message that must continue to be stressed and followed to reduce the potential for creating flyrock from blasting operations and to reduce the hazard it presents. A recent accident that resulted in a serious injury at a limestone mine in Pennsylvania bears witness to the ever-present danger of flyrock created from blasting operations.

Jan 1, 2007

By Jim Daly

The word “Enron” has taken on a totally different meaning since its leaders were caught juggling the books, President Clinton’s reputation was destroyed not by what he did but by how he tried to cover it up, Martha Stewart spent time in prison for not being honest. Our society is tolerant of mistakes we humans make but has become very critical about what we do following those mistakes. The blasting industry is in a similar position. We have all heard the stories of the tree stump that came down through someone’s roof, of the windows that were broken, of the casualties that occurred when a blast was not properly guarded. What was done following these incidents? In the mind of the public, not enough.

Jan 1, 2007

By Malcolm Scoble, Yves Lizotte, Ajit Singh

Fragmentation size assessment faces difficult problems, traditionally involving tedious and time consuming procedures. Early work had been directed towards developing empirical methods of predicting rather than measuring fragmentation. More recent development of computer-based image processing techniques which derive size distributions by analysis of photographic or video images are reviewed. These are now being adapted by various workers to fragmentation analysis in mines. Results are presented from experimental work aimed to establish the accuracy and precision of photographic techniques for muckpile assessment. Reference is made to McGill fragmentation studies at surface and underground mines in Canada, relating to experience gained in photographic and image processing techniques. The various factors that affect such techniques as well as their limitations and strengths are discussed.

Jan 1, 1990

By Andrew F. McKown

Overbreak and damage to rock walls at the perimeter of rock excavation can lead to safety problems due to rock falls and additional costs due to a] extra mucking, b] extra concrete or shotcrete to backfill overbreak, c] additional rock reinforcement, d] additional water inflow and e] additional maintenance of rock walls. To minimize these undesirable effects, there are several perimeter control techniques available (i.e. line drilling, cushion blasting, pre-splitting, smooth blasting, and fracture control blasting) which control perimeter hole spacing, burden and loading to provide a smooth, stable excavation contour. Conventional perimeter control loading and hole spacing is satisfactory for massive, homogeneous formations, but when blasting in weathered or fractured rock closer spacing and very light loading is required.

Jan 1, 1984

By L C. Taylor

Very small scale testing has been shown to be able to predict quite accurately, in many situations, the results of full scale testing. Small scale tests are more cost efficient, easily observed, and easily instrumented than full scale tests. Over the past 10 years small scale testing in the Dynamic Effects Laboratory at the University of Maryland has been used to successfully study the response of structures and soils to explosive detonation. Small scale testing has been successfully used to predict full scale results in underwater cratering and channeling, the loading (both pressures and impulse) on vehicles due to the detonation of buried charges, the positive effects of bottom shaping for military vehicles to reduce this loading, and the movement of obstacles underwater by explosive charges.

Jan 1, 2012

By Michael E. Kovach

This discussion is an overview of an approach to drilling and blasting angle holes at Martin Marietta Aggregates. Method of determining burdens, hole depths, angle settings and explosive selection will be discussed in detail with an emphasis on safety and production. Such techniques and methods involve the use of hand-held surveying instruments such as the Abney level, pocket transit and inclinometer along with measuring tape and burden pole. An interesting method developed by Oscar Banfield a retired Martin Marietta and E. I. duPont engineer, for setting the proper angle on a drill will also be presented. This treatise is a discussion of the use of simple yet important tools and techniques a blaster should use to resolve both routine and complex problems encountered during quarry blasting operations.

Jan 1, 1992

By Qi Jingyue, Wang Zhongquian, Yang Nianhua

Qinling Tunnel is the longest tunnel in China. The rock stratum is very hard rock - intact mixed gneiss. At the beginning of the construction, drift-pilot excavation is very costly due to the use of regular drill and blasting methods. After tests on the acoustic impedance match between rock and explosive, watergel explosive, which has a high velocity of detonation and high brisance, has been used for hard rock blasting. In addition, different cut plans have been compared. It was found that four-large-hole cut is the most effective. And the number of drillholes and specific charge cut down and the average advance reaches more than 94% of the blastholes depth. Thus, the difficult problem of hard rock blasting in drift pilot is successfully solved, while safe and quick construction is guaranteed.

Jan 1, 1998

By Jeff Wachendorf

As the title "Cast Blasting Around Town" implies, this paper details the starting of a cast blasting program in and around the town of Colstrip, Montana. As strip ratios have increased, the need to adapt and find solutions to provide coal at a reasonable cost to the captive power plants has risen. Colstrip, Montana has a long history of coal mining which dates back to the early 1920's when Foley Brothers began supplying coal strictly for powering locomotive engines. Early mining days starting in the 1920's and the progression up through the 1970's when mine mouth power plants were built will be discussed. To accomplish the desired results, early mining techniques included steam and electric powered equipment as well as a lot of actual horse power.

Jan 1, 2009

By Justus Deen, Paul V. Sterk

Through the 119 year history of the Homestake Mine various methods of raise mining have been used, these include conventional, bored, and drop raises. These raises provide passage for men and supplies, provide ventilation, transfer broken rock from level to level, and serve as emergency escapeways. As the 1980s came to a close, many of the larger ore bodies in the mine had been mined out. This has resulted in many crown pillar situations that required a method to mine them. In addition, the Homestake ore body also contains numerous ore reserves that have short vertical height. The ore itself can be from vertical to 50 degrees in dip. Due to the high cost of drift and ramp development many of these ore bodies are sub-economic using conventional mechanized cut and fill mining.

Jan 1, 1996

By Edward J. Walter

A vibration record is a complex of motions resulting from a combination of direct, reflected and refracted seismic energy that originated at a blast source. Multiple hole blasting using delays further complicates the motion in that overlapping of seismic wave trains may occur when delays do not fire in the programed sequence. This can result in variations in amplitude, frequency and wave-1ength of the vibration. Amplitude may be doubled, frequency may oscillate between the highest and lowest frequencies present and wave-length may approach doubling of the longest wave-length present. These effects can present serious problems to conducting a safe blasting program since increased amplitudes and lower frequencies present higher damage potentials for structures. The development of these effects is described and illustrated graphically to show how these effects can occur.

Jan 1, 1989

By Wendell W. Harris, Stanley J. Vitton

In the United States each year it has been estimated that expansive soils cause approximately $9.0 billion in damage to buildings, roads, airports, and other facilities. This figure alone exceeds the damage estimate for earthquakes, floods, tornadoes, and hurricanes combined. Unfortunately, some cases of expansive soil damage (swelling) are blamed on rock blasting operations if the blasting operations are located within the immediate area. While simple tests, such as the Atterberg limits test, can characterize a soil as expansive, it does not necessarily answer the question whether the foundation soils are causing distresses to a structure. In particular, it appears that once a soil has been labeled as nonexpansive it is no longer considered as a problem soil, in which case blast vibrations become the prime suspect.

Jan 1, 1996