Search Documents

By Lawrence W. Hallanger

Anaheim Bay, located at Seal Beach, California, is the site of the Huntington Harbor development of waterfront homes and marine facilities. The main entrance to Anaheim Bay is a relatively narrow channel connecting the bay with the Pacific Ocean which runs under California State Highway One. During the development of Huntington Harbor the old highway bridge was replaced with a new, higher bridge to allow for boat passage through the channel. At that time only the main span decking of the old bridge was removed, leaving the support pillars and the approach ramps in place (see Figure 1). The narrowness of this channel, plus the increasing boat traffic created a situation in which public demand for the removal of the old bridge became significant. Because the bridge was located within the boundaries of the Seal Beach Naval Weapons Station (see Figure 2) the Navy became involved in the bridge removal. Eventually the task was assigned to the Naval Amphibious Construction Battalion One and work began in early 1974.

Jan 1, 1975

By Michael Wieland

The work principle from thermodynamics is used to model the shock and heave for explosives shot in rock or under water, with the latter compared to reported results. The work principle utilizes restrictions and constraints to yield a representative fit to the irreversible (natural) shooting process. The reduction of the internal energy of the reaction-zone yields the total expansion work (TXW), the resultant sum of the rock/water shock and heave. The restoration technique of forming a closed thermodynamic loop yields the reversible mechanical work (RMW) or the rock/water heave. The residual work that remains when RMW is subtracted from TXW yields the irreversible disorder work (IDW) or the un-dissipated (without loss) shock in the surrounding rock or water. The work principle renders an unequivocal relationship for the shock-loss factor, rather than the traditional roundabout formula for correcting the underwater gauge-shock of un-modeled explosives. There’s a novel heave-ratio factor that unquestionably rates the fit of results under comparison. Rock-shots are more complex in nature than underwater shots due to rock fracture and stratum rupture, though numerical resolution is worthwhile. The proposed rock-water-jelly (RWJ) model yields rough estimates, with rock-type results not wholly different from their underwater counterparts. Though reported underwater shots reveal shock and heave trends with respect to charge formulation ingredients, there are no such rock-shot results for comparison, since the relevant test measurements in rock remain difficult, if not intractable.

Jan 1, 2007

Previous approaches to pre-split blasting theory have tended to concentrate on the mathematics of dynamic stress wave interaction, whilst only recognizing some interaction with quasi-static stresses induced by expanding gases in the boreholes. However the decoupling used in pre-splitting is specifically designed to reduce dynamic effects to a level that a small degree of radial fracturing is created around the borehole which is emphasized and extended by quasi-static gas effects. It can thus be argued that the process has more in common with hydrofracture than with more conventional use of explosives.

Jan 1, 1984

By Daniel Roy, Chris J. Preston, Ron J. Elliott

This paper discusses the use of pressure transducers in water filled boreholes in conjunction with surface mounted geophones to gather field data for in-situ dynamic rock properties determinations. A high speed collector is used to capture the data in the field. The calculated P and S wave velocities and rock density measurements are used as input into the Blastcalc program where the values of Young`s Modulus and Poissons Ratio are calculated. The rock properties information is used along with geological structural data and explosives properties in a 3-D blast modelling program to calculate predicted fragmentation distribution and other blast performance criteria based on the proposed blast design.

Jan 1, 1996

By Robert Hopler

Complying with our request in the February issue of the AGRICULTURAL BLASTER for items that would be of interest to other blasters, Mr. Thomas H. Benton of Tennessee sends us an article in which his methods of securing contracts are explained:

Jan 1, 2013

By Dale Ramsey

Located in the Chestnut Ridge Mountains of Southwestern Pennsylvania, the Casparis mine named for the founder Kenneth Casparis operated from 1916 until the early 1950. producing crushed stone for construction and railroad ballast. The rock was transported by aerial buckets to a railroad tipple nearly 1000’ (304.80 meters) below the mine. The mine property is now owned by the Pennsylvania Game Commission and is located in the Loyalhanna limestone seam with 4 primary entries that are approximately 40’ (12.19 meters) high by 30’ (9.14 meters) wide and extend over 2 miles (3.22 kilometers) into the mountain.

Jan 1, 2006

By Jody Todd, Ernesto Villaescusa, Ronald Lachenicht, Kelly Fleetwood

In the underground environment, characterisation of a rock mass during the mining cycle becomes increasingly difficult due to a lack of rock mass exposure for measurement or observation. In most cases rock mass characterisation occurs prior to mining by inspection and logging of exploration drill core, or prior to mass excavation through drive mapping for geological and geotechnical data. Characterisation strategies, if applied during the mining cycle, can reveal near-field anisotropies that may affect the behaviour of the rock mass with respect to excavation. These methods can aid in understanding the performance of stopes based on geometry, in-stope extraction sequence, and stress modelling. One such method of characterisation involves the use of production blast vibration monitoring and analysis as indicators of rock mass anisotropy through travel-time tomography.

Jan 1, 2008

By Shih Wen Wang, Ronald R. Rollins

A blast casting model is proposed to predict the burden velocity in bench blasting. This blast casting model is the first theoretical model that 1) explains the throwing procedures and mechanisms, 2) uses the explosion pressure as the primary source in throwing rock fragments, 3) applies them to field conditions successfully. Also the predicted burden velocities are based on the rock properties, the explosive properties, and the drilling and initiation patterns. This blast casting model is programmed into a computer software "ROCKFRAG". The comparisons between "ROCKFRAG" predicted values and two field test data are in good agreement.

Jan 1, 1992

By G E. Frantii

In the exploitation of low grade mineral deposits, blasting engineers are vitally concerned with maximizing the efficiency of explosive fracturing of rock while simultaneously limiting deleterious environmental affects to acceptable levels. Efficiency can be inferred from radiating seismic waves. Likewise, seismic waves carry direct information on damage potential. The usual approach to this problem is to measure the maximum signal level close to a blast, where it is difficult to instrument and where the signal complexity is intensified by mixtures of wave types and by local heterogeneities. Near-field sites are usually more easily monitored and more readily interpreted. Therefore, a study is being conducted to determine if variations in multi-hole, delayed blasts produce measurable changes in the spectra of seismic waves recorded in the near-field and if these spectra can be correlated with close-in strong motions and affects. To date, power spectra for the well-developed phase Lg and its early coda have been computed and are found to vary measurably when nominal changes occur in blast conditions. Up to a distance of about 50 km the spectra of Lg and its coda appear to be dominated by body wave characteristics (thus source-controlled), whereas beyond 50 km path affects seem to dominate. Additional data must be collected to fully explore the consistency of near-field Lg observations and to verify their usefulness as diagnostics of the engineering affects of blasting.

Jan 1, 1977

By Robert L. Martin, Brian W. Stump, David P. Anderson, David Gross

In an attempt to better understand the impact that large mining shots will have on verifying compliance with the international, worldwide, Comprehensive Test Ban Treaty (CTBT, no nuclear explosion tests), a series of seismic and videographic experiments has been conducted during the past two years at the Black Thunder Coal Mine. Personnel from the mine and Los Alamos National Laboratory have cooperated closely to design and perform experiments to produce results with mutual benefit to both organizations. This paper will summarize our activities, highlighting the unique results of each.

Jan 1, 1997

By Sarah Guzzelli, Enrigue Munaretti, Anneliese Botelho, Jair Koppe

Drill and Blast (D & B) is one of the main operations in the mining production cycle, which aims to fragment rock according to a pre-defined plan for proper loading, haulage and processing specifications. In this sense, data from a Brazilian iron ore mine was analyzed, given emphasis on blasthole length, subdrilling and stemming. The D & B report, including mining data such as number of blastholes, length, and diameter and stemming aspects, was analyzed in order to be able to compare these results with the blast design. The study showed significant differences between the designed blasting pattern and that one obtained by the operation. As a consequence, problems such as inadequate fragmentation, incorrect size distribution and loss of energy, were identified. For example, when stemming has a different length than it should have, noise and flyrock can occur, including inadequate fragmentation and vibration in both situations. Therefore, a comparison between the usual D & B procedures and recommended D & B design based on literature reveals the most important deviations and their consequences. The study intends to identify solutions for simple problems, improving D & B operations and safety practices.

Jan 1, 2014

By C. K. McKenzie

Presents outline of flyrock model and a field procedure to validate predictions of maximum projection distance. Field results are presented from 13 field tests with two different hole diameters.

Feb 1, 2020

By Gordon C. Petersen, Gary A. Almeraris

This paper describes the controlled blasting techniques required to mine a rock tunnel section of a main interceptor located in the Boston Metropolitan area. The 3m (10 ft) x 2.8m (9.25 ft) horseshoe shaped tunnel was driven 490m (1600 ft) by conventional drill and blast methods. The geology varied round by round and consisted of five highly faulted and jointed igneous rock types. The tunnel intersected numerous slickenslides and open mud seams which hampered both drilling and loading operations. Smooth blasting wee critical in order to keep overbreak tc a minimum in this extremely hard but blocky ground.

Jan 1, 1991

By Corry Goumans

The job location is at Bear Lake Hydro Project located north of the town of Sechelt, British Columbia, Canada

Jan 1, 2013

By Dal Sun Kim, Michael K. McCarter

"Comminution (crushing and grinding) of rock materials is energy-intensive and expensive. Mucheffort has been directed to improve the efficiency of conventional milling practice, but relatively littleattention has been given to the potential benefits of blast-induced damage on comminution processes. To help assess this effect, research has been conducted at the IRECO Laboratory and the Generic Center for Comminution at the University of Utah. The objective of this research is to investigate the effect of shockinduced “crack-like” damage on rock properties and subsequent breakage efficiency for three petrologically different rock materials under laboratory conditions. In order to evaluate the effect of shockinduced damage, a quantitative measure of rock damage is needed. For this purpose, a scalar variable (0) is proposed."

Jan 1, 1993

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 Saeed Karimifard, Saman Nouranian, Shahram Tafazoli, Bahram Sameti, Frank Chu, Caitlin McKinnon, Tetiana Konstantynivska, Glen Turner

We propose a particle size analysis solution for haul trucks that does not impact current operational workflows. Using artificial intelligence (AI) and 3D imaging technology, our solution reliably localizes and identifies haul trucks as they drive by, then accurately calculates the particle size distribution of the visible material in each truck load. In this paper, we identify the challenges of designing and implementing the proposed solution and explain the strategies we employ to overcome these. We also discuss a method for boulder detection that leverages the existing deep learning architecture to significantly reduce crusher downtime caused by oversized rocks

Feb 1, 2020

By Rafael Tadeu Pinto e Moura, Giorgio De Tomi, Jacopo Seccatore

This paper describes a research and development project in an open-cast mine with the goal to achieve an average P80 of 300 mm (11,8”) in the run-of-mine (ROM) product without altering the existing budget. The project included several variables in the blast design that were not previously taken into account, such as the orientation of natural joint sets in the rock mass, specific energy of the explosive and firing sequence. The new blast design method considered the directions of natural joint sets and determined the drilling pattern and the firing sequence accordingly to favor the movement of the blasted rock along its preferential direction, to reduce its confinement. At the end of the project, it was achieved an average P80 of 304 mm (12”) in the ROM, 50% lower than the one at the beginning of the project. The final blast of the project showed a reduction of 3% of the drill and blast cost, employing the same powder factor and the same drill pattern size used at the beginning of the project. The results achieved show how rock fragmentation is related to variables that are not contemplated in the most common fragmentation models: the firing sequence and the direction of movement in the blast.

Jan 1, 2015

By Quentin L. Rhoton

"The use of explosives in a surgical manner was approved to facilitate, due to time constraints, anextremely significant paleontological find in the Plunket Point area of the Dominion Range, Antarctica. The organic material revealed by surgical blasting techniques may have altered basic scientific dogma on Antarctic glaciation theory."

Jan 1, 1999

By David Lilly, Robert Ethier, David Bremer

The Lafarge Ravena Cement Plant in Ravena, New York demonstrated continuous and extraordinary improvement in productivity during the past several years. The factors driving continuous improvement at the Lafarge Ravena Plant include: 1) Management techniques including regular scheduled and effective Blasting Optimization Team meetings. 2) A real time blasting database to guide blasting product and procedure decisions. Key decisions involved all levels of quarry and blasting supplier personnel and a close working relationship between production and blasting areas of expertise was demonstrated. 3) Blast optimization and optimization of quarry operating parameters such as blast location relative to crusher location, hours worked, etc.

Jan 1, 2007