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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 R Holmberg, C Sjoberg, B Larsson

This paper describes the excavation of an underground naphta storage facility at Stenungsund in Sweden. The main purpose with this paper is to give an overall view of how the excavation was carried out and in what type of bedrock the storage was built. Emphasis has been done to highlight the importance of using cautious blasting to avoid blast damage in the remaining rock. Attempts has also been done in order to evaluate what the degree of Swedish cautious blasting has meant for the rock support costs during the construction period.

Jan 1, 1984

By Fred C. Drury

Blasting vibrations have been a concern to those using explosives since as early as 1927. Many criteria have been used to correlate vibration levels with damage to structures. After considering many alternatives, peak particle velocity has become the most commonly used criteria.

Jan 1, 1975

By C Yeung, G Fitz, R Heater, P D. Katsabanis

Explosives malfunction due to shock waves is a serious concern for successful blasting results. Malfunction can range from sympathetic detonation to desensitization and modification of firing times of conventional pyrotechnic detonators.

Jan 1, 1994

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 Brian Stump, Chris Hayward

Blasting operations at one copper mine are studied in detail to examine the relation between blast design parameters and near-shot, in-mine, and regional seismic and acoustic observations. Five observational experiments, namely collection of blast design data, near source recordings, GPS synchronized video, near mine recordings and distant regional observations were performed during one week in August. A variety of seismic and infrasound instruments were installed near the shot, on the perimeter of the open pit mine, and at several locations up to 500 km distant. Time tagged video recordings were taken of several shots. Three shots were used in the preliminary analysis, a 350,000 lb pattern with long delays, a 60,000 lb pattern with short delays, and a 256,000 lb pattern with short delays. Maximum peak-to-peak amplitudes of the seismic signals in the mine are not a simple function of the total size of the shot, but are related to the pattern timing. Peak pressures have a less clear relation to peak pressure but match the relative amplitudes of spectra modeled from the pattern design. The predicted spectrum based upon a simple impulse model fits the observed spectrum for ground acceleration measured near the pattern and explains why in this case a pattern of 60,000 lb results in the same seismic disturbance as the 350,000 lb pattern.

Jan 1, 2002

By Wilfrid Comeau

Vibrograms, which last significantly longer than the actual blast (say 10 to 15 cycles or more), may be signalling an elastic response, which is not uniquely blast related. For example, geophones mounted on a part of a structure, which can elastically resonate at a frequency included in the seismogram, may not show the structure’s real reaction to the blast. This resonance usually amplifies the ground vibration. This contribution examines one particular case where blasting excited and amplified a resonant ground response, and the method used to significantly reduce or eliminate this undesirable condition.

Jan 1, 2007

By B. A. Cheeseman, R. Skaggs, C. F. Yen, S. Wolf

Shallow buried explosives pose a significant threat to lightweight vehicles and their onboard personnel. To date, designers of lightweight vehicles are limited in their knowledge of what occurs during the blast. The high intensity, short term loading imparted by the explosion is enormously complex and can be significantly affected by a number of parameters including the size, shape, type, detonation point and depth of burial (DOB) of the explosive and the type, density and water content of the soil. Recent advancements in numerical simulations have enabled the complex blast event to be accurately modeled by coupling Eulerian and Lagrangian analyses: the former is well suited to modeling the blast and while the latter, the structural response. Further validation of the modeling technique is considered in the current paper, which details simulations performed utilizing the coupled Eulerian-Lagrangian analysis to the study the blast output of explosives buried in saturated sand. These experiments varied explosive charge size, its depth of burial, the target stand-off (SO) distance and target plate dimension. The investigation concludes with a discussion of the accuracy of the numerical simulations when compared with the experimental observations.

Jan 1, 2005

By Richard J. Mainiero, T S. Bajpayee

The U.S. Bureau of Mines (Bureau) has conducted research to evaluate the firing accuracy of electric delay detonators used in surface blasting operations. Over four billion pounds of explosives and blasting agents are used every year in surface blasting in coal, metal and non-metal mines. In a typical large-scale surface blast, several thousand pounds of explosives are fired in a timed sequence using delay detonators. The delayed firing of explosive charges allows time for the fragmented rock to move out before the next charge is fired.

Jan 1, 1990

By Rick Lamkie

When investigating citizen complaints about blast vibration and airblast, it is important to be able to establish the spatial relationships between blasts, blasting seismographs monitoring the events, and complainant structures to assess any directional impacts. The Pennsylvania Department of Environmental Protection (DEP) routinely uses hand-held GPS receivers to document these relationships. The waypoint (structures and seismograph monitoring locations) and tracking (blasting and permit areas) features are used to map a site. These data are imported into the software for editing and conversion to GPS Exchange (.gpx) format.

Jan 1, 2008

By Jennifer P. Harrell, D. Joseph Hagerty

In many areas of the eastern United States, especially in the Midwest, past mining activities have left large and extensive underground openings. Now, renewed mining is occurring in such areas in surface pits. Also, construction blasting often occurs in rock over such old openings. Within the last fifteen years, some attention has been given to the interaction between surface blasting and underground cavities; concern has been expressed about the possible changes in vibrations transmitted through areas underlain by old mine workings (Siskind, Stachura and Nutting 1987). Previous studies also had indicated that underground openings could influence transmission of surface mine blast vibrations (see, for example, Woodward-Clyde Consultants 1977). The principal concern is that underground openings under surface blasting may intensify low-frequency vibrations. If such intensification occurs, use of available equations to predict peak particle velocities and to design blasting patterns and select blasting parameters could lead to possibly damaging ground shaking.

Jan 1, 2002

By He Guangyi

During rock blasting in extending deep cutting from Jiu Li Mountain to Dong Zhuang Village in Jiao Zhi Railway line, we have drilled deep hole with large scale diving drilling machine and successfully carried on controlled blasting. This has provided new experiences for rock blasting in extending existing cutting. The aim of this article is to provide an introduction to bench height, blast holes arrangement, powder charge calculation, and detonating technique during blasting.

Jan 1, 1997

By James W. Reil, Douglas A. Anderson

Common wisdom has it that a blast which breaks rock efficiently should-generate less ground vibration. In practice, however, this idea has not been-rigorously tested. In a previous paper presented at an SEE meeting[1] we described a method for-controlling vibration using delays. The method is very effective in controlling-annoying low-frequency ground vibration. We noted that observed ground-vibration differs in some respects from that predicted by adding single-charge-waveforms.

Jan 1, 1988

By Mark S. Stagg, David E. Siskind

The Bureau of Mines arranged to have a wood-frame test house built in the pat of an advancing surface coal nine so it could investigate the effects of repeated blasting on a residential house. Structural fatigue and damage were assessed over a 2-yr period. The house was subjected to vibrations from 587 production blasts with particle velocities that varied from 0.10 to 6.94 in/s. Later, the entire house was mechanically shaken to produce fatigue cracking. Failure strain characteristics of construction materials were evaluated as a basis for comparing strains induced by blasting and shaker loading to those induced by weather and household activities. Cosmetic or hairline cracks 0.01 to 0.10 mm wide occurred during construction of the house and also during periods when no blasts were detonated. The formation of cosmetic cracks increased from 0.3 to 1.0 cracks per week when ground motions exceeded 1.0 in/s. Human activity and changes in temperature and humidity caused strains in walls that were equivalent to those produced by ground motions up to 1.2 in/s. When the entire structure was mechanically shaken, the first wallboard tape joint crack appeared after 56,000 cycles, the equivalent of 28 yr of shaking by blast-generated ground motions of 0.5 in/s twice a day.

Jan 1, 1985

By David E. Siskind

Increased mineral consumption and environmental concern have caused much interest in potential damage and annoyance from ground vibration and airblast produced by production blasting in surface mines and quarries. Ground vibrations are traditionally blamed for "shaking the house to its foundations," but often the airblast is responsible, particularly when the distances from mine to structure are large. Simultaneous measurements of ground vibrations, structure vibrations, and indoor and outdoor noise from blasting are being used by the Bureau of Mines to determine the relative importance of the ground and airborne blast energy in shaking the structure and making windows, dishes, etc., rattle.

Jan 1, 1977

By Doug Anderson

Two quantities, Peak Particle Velocity (PPV) and Scaled Distance (SD), have controlled aspects of many blasting projects and operations for a long time. Vibration criteria typically use both PPV and SD because they are simple to measure, and simple to calculate. Their use in regulations worldwide is fairly ubiquitous, in efforts to limit damage to structures in the neighborhood of a blasting operation. PPV and SD are also used to determine likely blast damage effects in mining operations.

Jan 1, 2018

By Jerome S. Brower

Quadrex-L is a two component liquid explosive which was developed by J. S. Brower & Associates, Inc. to facilitate handling and shipping, and use in unique applications, while emphasizing safety. It may be advantageously used for all explosive applications. Quadrex-L can be introduced into a preinstalled container configuration and may be easily drained or flushed from these containers when necessary to do so. This characteristic can be effectively utilized to reduce the hazard period during assembly or disassembly operations.

Jan 1, 1975

By Pierre-Louis Migairou

After a period of development and experimentation ranging over 20 years, electronic detonators have now come to maturity and are becoming the first choice in many diverse applications like tunnelling, civil works, demolition works, quarrying, large scale open pit mining and underground mining. This paper demonstrates the versatility of electronic initiation systems by detailing a number of case studies in several applications as different as their geographical locations, and gives specific reasons explaining the popularity of electronics in each case.

Jan 1, 2009

By Jaak J. K Daemen, Clayton R. Morlock

A study was performed to evaluate the predictability of airblast overpressures induces by production mine blasting. Thirty-seven production blasts were monitored using 3 blasting seismographs giving over 100 blast overpressure records. Blasts were monitored at 5 coal highwall operations and at a limestone quarry, all in the midwest. Blasts consisting of small surface charges were monitored to permit an assessment of prediction methods under controlled conditions, as well as to observe actual delay intervals and their influence on the overpressure.

Jan 1, 1983

By Lewis L. Oriard

Some two million cubic yards of sandstone and orthoquartzite were blasted and excavated at Upper Stillwater Dam, located high in the Uinta Mountains in northern Utah. The material was processed to produce concrete aggregate for the construction of the largest roller compacted concrete (RCC) dam ever constructed, and one of just a few in existence. The dam cross-section is shown in Figure 1. The aggregate was sound rock produced from required dam foundation excavation and from a quarry located about 1/2 mile from the dam site. Representative compressive strengths of the sandstones and quartzites were in the range of 20,000 to 30,000 psi.

Jan 1, 1993