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By P D. "Takis" Katsabanis

The phenomenon of sympathetic detonations in blastholes is investigated by comparing experimental observations and numerical modelling results. Numerical modelling using the TDL computer code and Forest Fire decomposition rates for commercial explosives has shown the importance of blasthole diameter, impedance of the stemming and host rock. Comparison with experimental observations has also shown that sympathetic detonations cannot always be treated as shock to detonation transition. Examination of previous results which have been obtained from calibrated low amplitude shock experiments reveal that there is an ignition threshold prior to the detonation threshold. The difference between the two thresholds is more pronounced in the case of air bubble sensitized products. The ignition threshold can be very important under the confinement provided by the blasthole and the conditions of application. It also correlates well with the pressures expected at the gap distances of interest in the practical application. It is suggested that critical energies are used as the criterion for cross initiation in blastholes. Practical suggestions based on the numerical calculations and experiments based on these calculations are also given and discussed.

Jan 1, 1991

By C V. B Cunningham

The assessment of blasting results under production conditions is extremely difficult. As a result, it can take months or years to establish objective and valid estimates of explosive performance in achieving rockbreaking goals. This fundamental problem often results in decisions related to the manufacture, marketing, purchase and use of explosives being largely swayed by calculated energies from detonation codes. However, these codes are by no means standardised. Different energies are given by different codes because these employ varying combinations of fundamental science and empiricism. After a basic review of code operation, important guidelines to dependability are given with reference to ICI’S state-of-the-art codes IDEX and CPEX. Distinctions are drawn between Ideal, Non-Ideal and Blasting Codes. Concepts of explosive energy are discussed in brief.

Jan 1, 1991

By Stephen H. Chung

The blasting performances identified above are considered to be the most practical ones for judging the effectiveness of a design combining explosives / rock / drill pattern. In a total blast design process, productivity relates closely to both fragmentation and heave / displacement of muck. In cast blasting, the more overburden displaced by explosives, the less blasted material there is left to be removed with mechanical equipment such as draglines or trucks. For wall protection and dilution control, estimates of the maximum extent of cracks / damage generated in situ due to blasting will help determine the location for drilling and loading perimeter blastholes.

Jan 1, 1994

By D. J. Leidel

The offshore production of oil and gas resources has been active in the Gulf of Mexico since Kerr- McGee drilled the first commercial well out of the sight of land in 1947. Since then, approximately 60% of the offshore oil/gas production structures used globally have been erected in the GOM to support the production of energy resources’. The shallow, shelf and shelf edge waters of the Gulf of Mexico have reached or are rapidly approaching production maturity, requiring that the fixed structures used to support energy production be removed or otherwise disposed of by suitable means. The use of energetic materials has been determined to be a safe, efficient and cost effective technology to remove fixed offshore structures whose service life has been exceeded.

Jan 1, 2002

By Sang Ho Cho, Masaji Kato, Masaaki Yamamoto, Masaaki Nishi, Katsuhiko Kaneko

This paper presents a numerical simulation method to predict rock fragmentation and to verify a fracture mechanism by bench blasting. The rock fragmentation, which has been used as a means of the index to estimate the effect of bench blasting, affects the expenses for loading, conveyance and crushing of blasting muck piles. The developed numerical simulation method is based on the finite element method and fracture mechanics and includes the re-meshing procedure to express the fracture process of the rock mass. This paper discusses a procedure for a determination of size distributions of the results, which were calculated by numerical simulation, including the tines.

Jan 1, 2002

By Alex Chapman, Cam Thomas, Bryan Karney

"During the early summer of 1989, Ontario Hydro removed a concrete portion of the North Channel Dam at Crystal Falls Generating Station by blasting and excavating in marine conditions. Because of the severity of underwater blasting and because the site was in close proximity to the replacement dam, there was concern that hydraulic shock waves generated by the detonation could damage either the new dam or its control structures. This paper examines the data associated with the hydraulic shock waves generated by underwater blasting, and studies the effectiveness of an air curtain in reducing the peak pressures. In previous trials using the air curtain technique, a rule-of-thumb factor was used to estimate that only 10% of the original pressure pulse would propagate across the air curtain. However, this value had little basis in theory. A theoretical formulation of the problem by Karney in 1989 indicated a provisional value of 0.18 for this factor, but was heavily dependent on confirmation from in-field testing. Data provided by Ontario Hydro from an actual blasting procedure indicate that a more conservative value of 0.32 may be more appropriate. Thus.although the air curtain did provide considerable reduction of peak pressures, the data at Crystal Falls indicates its performance was below the anticipated level. However, due to problems with the instrumentation and some inconsistencies in the resulting data. it is recommended that this value be further refined as additional data become available."

Jan 1, 1992

The objective in controlled blasting is to reduce overbreak to control the final pit wall slope, shaft, drift ditch, bench, etc. to the final planned excavation limit. The six main types of controlled blasting utilized today are: 1) Line Drilling 2) Cushion Blasting 3 Smooth Wall Blasting 4) Buffer Blasting 5) Presplitting or Preshearing 6) Air Deck Presplitting

Jan 1, 1992

By P D. Katsabanis

This chapter describes the principles for the derivation of the equations for a detonation wave. The importance of the equation of state for the detonation products is demonstrated and commonly used equations of state are discussed. Furthermore a brief introduction to the TIGER code is presented.

Jan 1, 1991

By Tianrui Xu, Chaohong Liu, Bangqing Ding

The authors were responsible for a series of large scale multiple chamber charge blasts conducted in the granite mountain area for making construction space on the southeast sea coast in China during 1993-1996. This paper describes the blast design and damage control of one mountain blast 320m in length and 280m in width in the vicinity of two wharfs and a dam. In order to obtain better rock fragmentation and muckpile, the explosive charge should be well-distributed in the mountain. The charge pattern, therefore, was designed with mainly 5 rows of tunnel charge in regular terrain in combination with a chamber charge in irregular topography area and the maximum burden was limited to be less than 38m. In order to protect the dam and wharfs the firing sequence was carefully arranged in 29 intervals and the distance between different charges of the same delay to the dam or wharf was taken into account as an additional delay interval based on the difference of p-wave propagating times. The maximum charge fired in an interval was also limited to less than 34t explosives through dividing the larger charge by a stemming deck.

Jan 1, 1998

By Jerry Wallace

The goal: At an industrial site, sever a well pipe containing an interior obstruction in a timely, cost effective manner by using a shape-charge to cut through the casing more than 50 meters below ground surface from the outside, doing so while inside a larger pipe, without damaging the larger pipe. The problem: Pumps and retrieval tools stuck nearly 50 meters below ground surface inside a 305 mm diameter by 9.5 mm wall thickness water well casing. The well, depth of 185 meters, had to be inspected for contaminates then properly decommissioned before industrial expansion could take place overhead. The limitations: A 508 mm diameter pipe had been driven around the 305 mm pipe to a depth of 63 meters. The usable internal diameter of the larger pipe was about 480 mm while the smaller pipe had buckled at one point forming a 350 mm wide spot. The charge thickness was limited to less than one-half the difference. Additionally, water that filled the annular space between the two pipes had to be displaced for the charge to work properly. The solution: Enlist the support of the shape-charge manufacturer to design, build and test a charge to work under the conditions present, then make it work in the field.

Jan 1, 2000

By Young-Dong Cho, Yonghun Jong, Dong-See Shim, Seokwon Jeon, Chung-In Lee

The most important operation in the tunnel blasting procedure is to create an opening in the face in order to develop more free surface in the rock mass. This operation is highly dependent on the cut holes. In general, the burn-cut or V-cut is commonly adopted to blast the cut section. But, these traditional methods often raise problems. There are instances (a) that the actual advance is considerably less than the designed advance depending on the rock mass, (b) that they cannot sometimes enlarge the free surface efficiently and (c) that the blast vibration resulted from the cut blast exceeds the allowable vibration level. In order to resolve the problems, many different kinds of the cut blast can be considered.

Jan 1, 2005

By Stephen H. Chung, Kevin Atherton

The main purpose behind this preliminary study was the reduction of costs while maintaining productivity. Finding a way to achieve this balance without compromising controls on safety and quality of blasting results is of continual interest to the mining industry and of particular interest when ore of lower grade is being mined.

Jan 1, 1998

By B Mohanty, G Yamin

A number of parameters, aside from blast design and pre-existing rock conditions, can change the performance of the explosives system in actual blasting practice. Sympathetic pressures caused by detonation of preceding holes have been identified as a major contributor to explosive system malfunctions, leading to uneven blasting performance. These effects can occur both within a hole or across several holes. These can consist of high transient pressures related to the shock phase of the explosion or the relatively longer or quasi-static pressures associated with the explosion gas expansion phase. This study presents the findings from an on- going investigation on measurement and analysis of these pressures between donor and receptor holes in a granitic outcrop for representative inter-hole distances and borehole conditions, employing single cartridges of emulsion explosive in 45 mm diameter holes. The results, despite wide scatter in the measured values, show the very short duration pressures to range up to 7 MPa and arriving within a few milliseconds after detonation, whereas the much lower amplitude pressures arrive after tens of milliseconds. Both have the potential to seriously affect the performance of an explosives system.

Jan 1, 2005

By R F. Hoeberling

"The use of ground penetrating radar (GPR) for geological purposes has been underway for almost two decades. The commercial need for a versatile GPR that can rapidly identify buried objects andunderground voids has been recognized and is an area of research that has already proved useful for several geological activities. Several types of GPR endeavors have been reported in the literature, including exploration of placer deposits (Davis, et al. 1985) and heavy metals (Hammond and Sprenke, 1991), improving oil recovery (Witterholt and Kretzschmar, 1984), investigating coal seams (Coon, et al., 1981), stratigraphic survey (Fisher, et al. 1992), Lunar soils characterization (Olhoeft, et al. 1975 and Strangway, et al. 1977), characterization of rock around mine tunnels (Cook, 1985), location of old mine workings (Scaife, et al., 1992), location of abandoned gas wells in coal seams (Kemerait, 1992) and survey of hazardous waste burial areas (Horton, et al., 1981). Coal seammapping has been developed using a related continuous wave, phase discrimination technique (Stolarczyk, 1990). As the technology for the radar equipment and the onsite computational power has increased, many new applications have become feasible. This article will describe the present status of the GPR technology and indicate some of the exciting possibilities for nearterm prototypes now being constructed."

Jan 1, 1994

By R Tom Watts

The blasting industry has changed more in the last five years than in any period to date. The equipment utilized to load boreholes has changed in response to more precise blasting products and programs, and the need to maintain tighter control over product formulations produced by bulk loading equipment. Tread Corporation has built over 1,300 heavy ANFO type bulk loading units currently operating in over 40 countries worldwide. These units have been designed to meet almost every possible loading scenario but there are always new situations that require special designs and configurations to meet the challenge. The focus of this presentation is to make you aware of the process that should be used to determine the equipment best suited for your application. We will discuss loading cycle times, delivery rates, multiple product mixing capability, capacities, manpower utilization, regulatory compliance, and where and when to use automation in the loading process. We will also discuss the suitability of chassis with regard to ground pressure, turning radius, terrain, weather conditions as well as highway suitability. The US Bridge Law as well as laws that cover the concept of axle loading and spacing will be covered. Through new computer aided design and modular design capabilities, you can now have almost any configuration required to meet your bulk loading objectives. We will also review the range of equipment currently available in the market place and discuss tradeoffs between price, capacity, and complexity.

Jan 1, 2000

By Brian W. Stump

"Seismic waves from explosions can be used to characterize physical processes in and around the source. The quantification of absolute levels of ground motion is important for minimizing impact on nearby people and structures. We contrast work in characterizing seismic radiation from contained nuclear explosions with ground motions from multiple explosion quarry blasts. A physical basedunderstanding of the explosion source function allows prediction and extrapolation to new environments where experimental data may not exist."

Jan 1, 1990

By Brian Gar Wingfield

Bulk explosive systems have developed from the infancy stages in the early sixties to a sophisticated process of the nineties. With ever changing bulk explosives technology, bulk delivery and loading systems needed to keep pace. Efficiency, as compared with packaged loading, was the keyword allowing faster loading of trucks and shots. Efficiency was also improved by the explosives coupling factor that bulk loading permitted.

Jan 1, 1991

By Steve Dillingham

The explosives business by nature is providing a specialized, valued service and associated products to a variety of customers whether mine, quarry or construction related. The level of performance demanded by the customer will typically coincide with his or her individual needs. Some will seek out the skills and knowledge of a blasting expert, while the focus of others is simply on production amounts.

Jan 1, 2003

By Lee B. Paterson

Mining Engineers throughout the world have an appreciation for the importance of the role of the Blasthole Drill in one of the primary elements of the mining process. This paper highlights areas that could influence the overall cost effectiveness of that process of breaking rock and the associated downstream mining and ore recovery activities - and how the drill is designed and configured to meet that challenge. Factors influencing drill productivity and overall cost effectiveness are addressed, particularly regarding the benefits which are not necessarily reflected in the drilling process and therefore more difficult to quantify. This paper explores some of the downstream benefits of what we do to the drilling process.

Jan 1, 2000

By Douglas Bartley, Brian Wingfield, Robert McClure

Recent studies and limited tests indicate favorable results utilizing high accuracy electronic detonator technology over conventional non-electric pyrotechnic systems. This study discusses the application of this technology using the Daveytronic programmable system in an on-going production basis. The study quantifies the performance as it relates to fragmentation, excavation, vibration and productivity in an eastern U.S. aggregate mining operation.

Jan 1, 2001