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By David Yanez

The hydroelectric project "El Cajón" is currently under construction in the state of Nayarit, on the Santiago River, in western Mexico. This project is comprised of a Concrete Face Rockfill Dam (CFRD) with a rockfill necessity of 10,5 million cubic meters and it reaches a height of 188 m. The generation equipment includes two turbines with a total installed capacity of 750 MW.

Jan 1, 2006

By J R. "Dick" Daniel

In the fall of 1988, The Cannon mine decided to investigate a central blasting system based on conventional electric blasting detonators being used to initiate rounds primed with Nonel detonators. The advantages of this hybrid detonator system were viewed as being safety and cost effectiveness. A study was done reviewing the safety aspects of utilizing a permanent blasting line installed throughout the main haulage drifts to a central blasting station located at the mine portal. The study addressed the following potential safety hazards: radio frequency induced current, stray current from both electrical utilities and transmission lines, galvanic and electrostatic sources of extraneous current.

Jan 1, 1989

By William R. Adamson, Carlos R. Scherpenisse

The successful development of surface mining operations depends, amongst other factors, on the successful creation of final pit walls which offer long term structural stability. The achievement of such walls will be much more feasible if the mechanisms of rock mass deterioration in the mine are well understood, permitting the control and reduction of this deterioration (or damage). The role of drilling and blasting in causing damage is widely accepted but rarely fully quantified. It is also true that the dependence of rock mass damage on vibration levels is only incompletely understood and little accurate field measurement is routinely conducted in the mining industry.

Jan 1, 1998

By Richard W. Watson, Julius Roth

The Bureau of Mines has recently completed a contract study of the hazards associated with surface mining.! Part of this effort involved an analysis of surface mining accidents associated with blasting activities. For this purpose, 71 reports of accidents investigated by the Bureau of Mines or the Mining Enforcement and Safety Administration (MESA), covering the period from 1962 to 1976, were collected and analyzed. In addition, blasting accident frequencies for the period 1973-1976 were extracted from the central computer files maintained by the Health and Safety Analysis Center (HSAC) in Denver, Colorado. This paper presents a preview of the findings, which are treated in more detail in the final report.

Jan 1, 1978

By Clive-Workman Davies, K K. Kabongo, Mensah Frimpong

Given the capital intensity of the dragline operation coupled with rising cost of explosives, the onus is on mine operators to make maximum use of explosives in blasting to assist dragline diggability. At a surface coal mine in South Africa large boulders necessitating secondary breakage and in some cases completely unfragmented sections of a blast resulting in low dragline diggability were encountered in the interburden blast. Twelve blasts were therefore closely monitored and dragline productivity evaluated. The ultimate aim was to improve the overall blasting performance and hence increase dragline productivity. Three areas were in focus; fragmentation assessment, dragline productivity assessment and cost analysis. The studies indicated unsatisfactory explosive and initiation performance, problematic blast design and questionable operators performance. It is established that dragline cost account for 60% of the total mining cost whereas the drilling and blasting cost account for the remaining 40% and that improvement in dragline productivity results in automatic cost saving.

Jan 1, 1996

By Earl C. Hutchison, John Loviza

At the Metropolitan Nashville International Airport, with its more than 600 scheduled daily flights from American Airlines hub operations, other scheduled airline flights, Tennessee Air National Guard operations, as well as numerous industry air flights, the excavation of 300,000 cubic yards of rock was required without disrupting airport operations for a cut and cover underground tunnel with a 4 lane US Highway and new airplane runway to extend across it's top. In addition to the excavation, the removed rock was to be broken to specification type that was clean and of small size for fill in another area of the airport property. The blasting was limited to two 1/2 hour windows per day and stiff monetary penalties were in place for schedule slippage of each phase of the project.

Jan 1, 1992

By Gerald G. Schmitt, Richard D. Dick

Continuous Reflectometry for Radius vs Time Experiments (CORRTEX) was used to monitor several conditions of blasts such as the detonation velocity of the explosive column, the functioning of different types of initiators and initiation schemes, and the behavior of the stemming column confining the explosive. The CORRTEX data were also used to deduce the occurrence of dead pressing of ANFO slurry. Measurements of propagation speeds of shock waves in the stem column with various cables allowed some conclusions concerning bridging, stem failure, and stress levels in the stem.

Jan 1, 1985

By Adrian J. Moore, Alan B. Richards, Rob Evans

Air and ground vibration from blasting is influenced by the delay pattern that is used. Wavefronts from blastholes fired in a blasting pattern can combine in certain circumstances to give increased blast vibration levels. A simple computer model has been developed which shows the combined effect of wavefronts from a multi-hole blast and identifies if wavefront reinforcement occurs, and permits delay patterns to be designed which will avoid or reduce wavefront reinforcement.

Jan 1, 1994

By Glenn Ludwig, Stephen H. Chung

Fragmentation has a direct impact on mine costs and productivity. Computer programs have been developed to calculate fragmentation using data on the properties of the explosive, the characteristics of the rock, the rock mass and the blast pattern. While computer models can yield good data, conclusions must be verified. Fragmentation assessment, muckpile surveys or high speed film analysis of rock mass movement are some of the techniques that have been used to confirm blast results. Digitizing photos of the muckpile is now the most common method to assess fragmentation. But it has some drawbacks. Although automatic electronic imaging equipment speeds up the process, the results depend on the photographs. Shadows will distort results. High resolution, black-and-white prints are essential.

Jan 1, 1992

By K. G. Holley

Blasting is usually required to produce easily-excavated broken rock, while leaving surrounding rock masses as undamaged and stable as possible. In mining applications, it is common to utilise production blasting in the centre of an open pit, and specially developed limits blast designs when blasting adjacent to the excavation perimeter. In open pit blasting, limits blast designs generally include pre-splitting, trim blasts, or buffer blasts, all of which are designed to limit, or eliminate, damage beyond the designed pit wall. This paper reports on the findings of a study of the profile of damage in rock masses surrounding blasts, determined by a combination of vibration monitoring, displacement monitoring using extensometers, and video inspection of open holes drilled at various distances behind blasts. The results obtained suggest that the profile of damage may extend for the full depth of the bench, for distances of up to 12 to 15 metres behind blasts. This suggests that entire berms may be affected by blasting, displaying loss of friction and cohesion along joint and fracture planes. The study has considered production blasts and trim blasts with small diameter blastholes and pre-splits.

Jan 1, 2004

By Jesus Pascual, Jose Sanchidrian, Pablo Segarra

The surface vibration field in the area above an underground mine prior to its development has been investigated, in order to assess the vibration levels expected in existing buildings and in the planned mine facilities from future underground blasts. Shots of 50 and 100 kg of explosive placed in drillholes at depths of 100 to 150 m were fired, and the vibration events were recorded using an array of 40 seismographs in a 400 m square grid, covering a 2×2 km area. Contours of isovelocity were obtained for each shot, showing some directional transmission patterns. Propagation laws were obtained from the results of each shot and also from the bulk of data, both for the whole area and dividing it into four quadrants. The shift of dominant frequency with distance was also analyzed.

Jan 1, 2002

By Syed Haq, Kyle Optt, David Campo, Doug Anderson

Limitations on allowable levels of vibration from construction activities generally consider either annoyance or damage. While activities such as drilling and roller compaction primarily create annoyance, the major concern for blasting is usually damage. Many years of research have developed correlations between peak particle velocity and either threshold or structural damage. We emphasize the term “correlation” for two reasons. First, peak particle velocity is only a single-valued representation of a vibration waveform, and does not characterize it completely. Second, a given peak particle velocity by itself, even a particle velocity waveform, will not damage anything – strain does. Why not measure strain all the time? Strain is very localized, and can vary substantially over short distances, so choosing the appropriate strain measurement can be difficult. Measurement of strain is appropriate when either the behavior of a specific structural element is needed, or the overall response of a structure can be adequately represented by a well-selected strain measurement. We will discuss the appropriateness of both particle velocity and strain as deformation and damage descriptors, in general. We will also describe a specific case history, from a tunnel project in New Jersey, correlating strain with peak particle velocity. Finally, we will make recommendations for the choice of measurement type for some common situations.

Jan 1, 2004

By Melvin A. Sannes

The explosives industry is recognized as one of the most dangerous occupations in the world, yet it is rare to see actual training procedures. As our industry becomes increasingly technical, it is imperative that we train the personnel in OUI industry properly.

Jan 1, 1999

By H J. MacDonald

An Exploding Bridgewire Detonator (EBW) is an explosive initiator which contains only secondary explosives such as PETN and RDX. It is safer than the normal blasting cap because it requires both high electrical energy and a very fast application of that energy to function

Jan 1, 1981

By Frederick R. Cosgrave

Blasting near buried Natural Gas pipelines has always been an area of great concern. Given the many variables that the blaster must contend with in determining how to break the rock while trying to keep the vibration low and doing so while not compromising the pipeline.

Jan 1, 1995

By Kai Nielsen

A model has been developed for sensitivity analysis of open pit bench blasting. The model simulates the cost effectiveness of various blasting designs in relation to the equipment used for drilling, loading, hauling and primary crushing. The simulations will give an indication of the optimum powder factor giving the lowest over-all costs for drilling, blasting, handling and crushing.

Jan 1, 1985

By A Lance McAnuff, Andrew Curic

Until relatively recently, underwater blasting operations for channel deepening, dock construction and pipeline crossings of lakes, rivers and streams were conducted without much regard for the potential side-effects on aquatic organisms.

Jan 1, 1997

By Duane A. Houkom

Down time in the Oil Refining and Petro Chemical Industry is extremely expensive. Each day of non-production may easily cost several million dollars. Explosives have been accepted by this industry to solve many of its problems. Explosives offer a solution which is faster, more economical and most important, safer than many of their methods. Our specialties for these industries include: Refractory removal, industrial cleaning, metal cutting and concrete removal. This report does not include information on concrete removal.

Jan 1, 1982

By Gregory P. Lorsbach

Significant information about any blast is contained within the seismic signal generated by the blast. In this study, standard digital signal processing techniques are utilized to extract source parameter information from a seismic signal recorded at distances commonly used in compliance monitoring. Specifically, digital seismic data was analyzed using the cross-correladon and autocorrelation functions for the purpose of determining delay timing. The initial results are interpreted to indicate that: 1) Individual delays can be identified analytically but not visually for short delay periods and large source to receiver distances, 2) Delay timing can be resolved to a few milliseconds, and 3) Results can be obtained from data collected at a minimal number of locations.

Jan 1, 1991

By Rahim G. Haghighi, Calvin J. Konya

Fragmentation is the fundamental concern of rock blasting and it measures the effectiveness of blasting. Fragmentation is sensitive to not only the interrelationship among the design variables, but also is sensitive to local geology. Local geologic conditions have a significant impact on the success of a blasting operation.

Jan 1, 1986