Search Documents

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 He Guangyi, Han Zhilong

This paper introduces the new technology of deep-hole blasting with water-soil mixed stemming to exposed stonework. Nine aspects of advantages are drawn in the paper based on tests of different types of charge and stemming under the conditions of different geology, height of bench and diameter of drill.

Jan 1, 1998

By Kirstin Girdner, Vicki Seppala, Tom BoBo, John Kemeny, Mike Higgins

Optimal blast fragmentation is fundamental to all phases of comminution. Changes in blast design may affect efficiency and productivity of downstream processes such as crushing, milling and leaching, resulting in cost savings or losses.

Jan 1, 1999

By Dennis Dobson, Keith M. Henderson

Lone Star Industries, Inc. in Cape Girardeau, Missouri operates an open pit mine to produce limestone for its portland cement manufacturing plant. The present mining method, for safety and legal reasons, requires a set back from the property line, a berm, sloped overburden, and vertical rock walls with catch benches.

Jan 1, 1997

By Greg Mclellan, Mark Johnson, John Pepper

In this paper, the measured vibrations are plotted in terms of the individual PPV components versus Scaled Distance (SD) on logarithmic scales. The maximum PPV is pIotted on a separate graph and equations are presented to predict the maximum PPV based on sealed distance and prediction level usmg power fits. The prediction levels include a 99.9% curve, which encompasses the data points and provides an envelope formula for determining the maximum PPV at South Florida sites. The dominant frequency distribution is established for the PPV components.

Jan 1, 2001

By Joshua Hoffman, Catherine Johnson, Braden Lusk

The practice of dual initiation using precise timing from electronic detonators in boreholes is thought to be beneficial for increasing fragmentation at a desired location in the rock strata. This increased capacity for fragmentation is understood to be a product of both the collision of detonation waves in the explosive column and an increased energy liberation rate, each resulting from dual initiation. In addition, the collision of shock waves from two adjacent blast holes is suggested to improve fragmentation at the location the two shock waves meet, which can be controlled with precise timing. This paper presents the results from scaled laboratory experiments where converging detonation waves and shock waves were studied.

Jan 1, 2014

By D K. Joyce, B Mohanty

In a previous paper, it was shown that a lack of clear understanding of the role of initiation mode on detonation characteristics often leads to under-utilization of the explosive system in blasting. This is of particular significance since the very large number of explosive initiation practices currently in use implicitly assumes that the blasting performance of an explosive is largely independent of the exact mode of initiation. This paper deals specifically with bulk-loaded and pneumatically-loaded ANFO under various initiation modes in small diameters. These include initiation by booster and detonating cords of various strengths, and combination of cords and boosters. The nature of energy release and energy partitioning between shock and gas energy have been studied in the underwater test as a function of charge diameter. The paper describes the relative merits of various initiation modes for specific charge geometries and confinement, under end- and side-initiated conditions. Guidelines have also been formulated for use in the field to match initiation practice with blasting requirements.

Jan 1, 1994

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 Raúl Mondaca Aracena

Mantoverde mine requires increasing its production level to double. EMTS - Projects performs far and near field vibration studies to make changes to the D&B design and sequences, in order to equalize the current vibration levels, applying massive blasting in its process.

Feb 1, 2020

By Italo Onederra, Gary Cavanough, Ewan Sellers

Reactivity of ammonium nitrate based explosives is associated with the presence of iron sulfides in the ground reacting with explosive products and in some instances causing spontaneous reactions which can lead to detonation. The stability of explosive products can also be linked to in-hole density, which influences detonation efficiency, breakage performance and the potential generation of Nitrogen Oxide (NOx) fumes. Reactive ground testing involves detecting a temperature rise of a mixture of a bulk explosive product sample, a ground rock sample and some specific chemical agents. This paper describes improvements in reactive ground testing involving the use of time lapse video analysis and detection of NOX gas emissions from the sample. Reactivity is stored and linked to a using cloud based software to map of the mine showing the exact location of the sample. The location marker can be selected to allow quick access to the sample test results and video. In addition to reactivity, the stability and detonation performance of bulk product can also be influenced by depth. In this paper, a system that simulates product at depth and measures density changes and monitors the structure of bulk samples is described. Results from an explosive product are analyzed and detonation performance is assessed by the measurement of velocity of detonation and detonation pressure.

Jan 1, 2018

By Thomas M. Keevin, Gregory L. Hempen

A user-friendly model for environmental effects from underwater explosions is presently available. The model by Munday et al. (1986) is effective for determining fish mortality radii from underwater shooting. The IBLAST program (Coastline Environmental Services 1986) from this model includes estimates for both borehole-loaded explosives for demolition or rock removal purposes and midwater shots. Midwater shots may be used for fish population assessments or some seismic surveys. The program produces approximate mortality distances for planning purposes. IBLAST does have serious shortcomings of which users should be aware.

Jan 1, 1995

By Jose Pineda, Abraham Lindo

The Panama Metro System’s Network expansion involves excavating a launching shaft for a tunnel boring machine (TBM) to traverse beneath the Panama Canal. The blasting needed for this shaft construction poses significant challenges due to the presence of concrete walls encircling the excavation. These walls must remain intact throughout construction and the tunnel's future operation. This case study is focused on devising and implementing safe blasting techniques crucial for the shaft's construction, ensuring the preservation of surrounding concrete walls and project equipment. As the interest was potential damage to the concrete walls, an appropriate vibration threshold for this project was also required as an alternative to the traditional U.S. Bureau of Mining RI-8507 limit (USBM RI8507). Blast modeling software was employed to conduct a series of blasting simulations. Parameters like hole diameter, spacing, depth, explosive type, and initiation methods were varied to evaluate their potential effects on wall stability and damage risk. The simulations revealed that smaller diameter holes and reduced spacing between blast holes would effectively mitigate the risk of wall instability. Additionally, utilizing electronic delay detonators and carefully planning the blast hole detonation sequence proved critical in minimizing potential damage. Executing these blasts in the field presented unique challenges, including strict charge per delay thresholds and logistical constraints. Consequently, continuous adjustments to blasting parameters were made and comparative result analysis. Beyond providing a safe blasting strategy for the TBM launching shaft, this study offers invaluable insights into adapting blasting designs to align with environmental and structural safety standards. These findings hold great potential to shape guidelines for analogous sensitive construction projects. They underscore the importance of leveraging prior research as a reference point, engaging with project designers and local authorities, and continually conducting testing and adjustments to ensure project success.

Jan 21, 2025

By Karl Christopherson, Vanessa de Viterbo

Trim blasting is an integral part of the mining processes at the Morenci Mine, a Freeport-McMoRan Copper & Gold Inc. property. Trim blasting near high-walls or Finals blasting requires a tighter distribution of energy but a reduction in total energy factor near the wall. Recent Finals blasting in Morenci Mine was allowing the shovel to dig to the final design limit, but causing high-wall instability due to excessive energy or production of energy (blast design and timing). Slope instability events reduced production in two of the three operating pits in Morenci over 2009. In order to avoid high-wall instability from Finals blasting, a new method was required. The new method utilizes air-decks, unconventional row timing, and blast design based on the geology predicted. Many different geologic structures and rock types exist in Morenci, and different strategies were needed for the many predicted geologies. Drill penetration rate and core mapping were the primary tools for determining the blast design. Patterns were designed within a consistent geology; with weaker rock types receiving a lighter load than the stronger rock types. Penetration rate returned by the drill would be the determining factor on the actual rock hardness. Maintaining the pattern geometry on Finals designs should not be an issue as long as the lb/hole is adjusted to reduce powder factor close to the high-wall. One requirement of Finals blasting should be that the powder factor matches the geology as closely as possible. A softer, fractured zone should use approximately one-half to two-thirds the explosive charge of a competent, sound geological zone. This has been incorporated into the final Trim blast design. It is impossible to protect every high-wall from close-in blasting, especially those with crossing prominent joint sets inclined toward wedge failure, but this new design has provided protection on walls where the mine was encountering problems.

Jan 1, 2011

Investigating blast vibrations typically utilises scaling and attenuation models for prediction of vibration amplitude over a range of charge weights and distances. A number of generalised relationships have been established from many years of far-field data analysis, where small changes in charge weight and ray-path distance are less critical. Under far-field conditions, small variations in local geology or geometry do not significantly affect the vibration scaling behaviour over an expected range of data. In the near to intermediate-field (less than 5 times the explosive charge length), small variations in wavepath and rock mass conditions between a blast and a monitoring point can greatly affect the outcome of vibration modelling. This case is especially true for underground blasting in sublevel open stoping, where the paths of blast-induced vibrations regularly encounter voids and preconditioned ground.

Jan 1, 2010

By Kai Nielsen

Drilling and blasting design results in a fragmentation that will have an important economic influence on all subsequent operations such as loading, transport secondary blasting and primary crushing.

Jan 1, 1987

By M Oldenburg, P J. Digby, L Nilsson

A constitutive model for the simulation of fracture and fragmentation processes in rapidly loaded rocks is studied. The model was included in a wave propagation finite element code. The results obtained from two different configurations of explosive charge and reflecting surfaces in a plane strain problem were studied. The evolution of the time-dependent fracture pattern is presented.

Jan 1, 1985

By John A. Franklin, Norbert B. Maerz, D Linn Coursen

Accurate measurement of blast fragmentation is important in mining and quarrying operations, to monitor blasting and optimize blast design. A new digital photoanalytical method to measure the block size is presented here. Photographs of the broken rock are digitized, apparent size distributions measured, and corrections made for overlapping blocks, by means of an empirically derived correction function. The method was tested during recent full-scale blasting tests in Virginia, USA. It shows great potential as a practical aid to predicting, monitoring, and controlling the quality of the fragmented rock.

Jan 1, 1987

By Yoshiharu Tanaka, Keita Morooka, Masaaki Yamamoto, Katsuhiko Kaneko

Smooth blasting is the standard method for underground rock excavation, to reduce over break and remaining rock damage. We already utilized the high accuracy of the electronic delay detonator to investigate its effect on over break remaining rock damage, and surface smoothness. And we presented at 11th annual symposium on Explosives and blasting Research.

Jan 1, 1998

By Conny Postupack, Jim Petrunyak, John Hope

The authors discuss the concepts, engineering considerations, and cost relationships involved in the use of drilling and blasting to accomplish backfilling and reclamation with minimum use of mechanical equipment. The four xchods o f reclsnacisn now in use are reviewed, and their advantages and disadvanrages a r e nocea. Guidelines for seleccrng a particular method are offered in terms of applicability under varying geologic, economic, and technological condirions.

Jan 1, 1989

By Thomas C. Jones

The purpose of this paper is to disseminate new information for nonelectric blasting in trenching and construction work. The presentation is not designed or intended to discredit conventional electric detonators or use of MS connectors and cord. Its sole purpose is to inform the S.E.E. of new and exciting benefits realized by the use of the Hercudet non-electric system in the construction industry.

Jan 1, 1984