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By S K. Mandal, S Dasgupta

"Damage is classifi ed as loss in the integrity or deterioration in the quality of rock massand is infl uenced by methodology of excavation on the geo-technical properties of rockmass. Overbreak, on the other hand, is the result of damage and is quantifi ed in either of the terms viz., extra mucking, shot-creting, application of extra support system and extension of scheduled completion time. Damage or overbreak in rock mass by the impact of blasting, is generally unavoidable but, the magnitude can be minimized so that it does not deteriorate the quality or integrity of structure. The paper, here, analyses magnitude of overbreak of a powerhouse cavern with respect to different blast patterns implemented at the site. The magnitude of overbreak was analyzed in terms of profi le measurement with the help of laser profi ler and percentage of halfcast markings observed on the periphery rock wall. The paper revealed the impact of decoupling ratio, blast pattern and geometry of blasting patch on the magnitude of overbreak. The authors observed that presence of un-favourable joint pattern or foliation plane along the periphery rock wall couldn’t contain magnitude of overbreak within allowable limit. The analyses revealed that percentage of half-cast markings on periphery rock wall was infl uenced by response of rock towards detonation of explosive and cannot be a single parameter to assess the effectiveness of a blast. The analyses also revealed that magnitude of overbreak for down-stream wall was more than that observed in up-stream wall."

Jan 1, 2008

By Larry Schneider

In the construction field and to a lesser degree in mining, flagman are often necessary to move traffic and or pedestrians through work zones. Everyone readily recognizes that they are essential for the safety of the general public and the employees on the job. What is not often considered is the safety of the flagmen themselves. Actually, let’s call these employees “flaggers” recognizing the fact that there are as many women as men doing this job. The first problem we need to overcome is the misperception that flagging is a low skill function that can be done by any untrained employee. The reality is that the flagger works in a very hazardous position with serious responsibility for the safety of his fellow employees and the public at large. And to do this job properly re q u i re s that the flagger receive sufficient training before being sent out to the highway. It is also necessary to convince the flagger of the value and importance of their job in order to motivate them to do a professional job.testing, documentation of both, and accurate re c o rdkeeping are key aspects of HM126F. Of course, training and documentation requirements will vary depending on the type of operation involved, and there may be some differences in the application of requirements depending on your jursdiction. Nonetheless, failure to train and properly document such training can result in heavy fines and/or penalties.

Jan 1, 2004

By Leslie Taylor, W. L. Fourney, Uli Leiste

Over the past few years, our laboratory has been investigating the loading on vehicles due to the detonation of buried explosives. We have been using target plates to represent the bottom of the vehicles that were being subject to the forces from the detonating explosives. Parameters shown to be important in the blast loading were type of soil, stand off distance (distance from the surface of the soil to the bottom of the target plate), and depth of burial (distance of the charge center of gravity to the sand surface). We conducted over the first year of our work a large number of tests which looked at the impulse being applied to the plates as a function of depth of burial, stand off distance, and type of soil. Of the three parameters we found stand off distance to be most important, depth of burial to be the next most important parameter, with type of soil least important. We also found that impulse could be scaled with explosive size quite accurately and that results (for impulse) were quite repeatable from one test to the next.

Jan 1, 2008

By Isaac E. "Chip" Harris

Any contractor who agrees to supply materials or to perform services for a sum, is well aware of the importance of proper pre-bid information. Being able to properly plan costs and methods results in profits that allow the contractor to prosper. The paper discusses procedures used in estimating pre-bid cost; in particular, drilling and blasting cost for highways, dams and general construction projects. It breaks cost down into five categories and relates them to a total estimate used in bidding and budgeting a construction project.

Jan 1, 1975

By Joshua Micah Hoffman, Lifeng Li, Jhon Silva-Castro

Since millisecond detonators were first introduced, at least two variables among others have been more closely considered when timing a mining blast; the accuracy and the precision of the initiation system. Unfortunately, those variables are often ignored when designing timing for mining blast. Despite the lack of consideration of the characteristics of the initiation system, in some situations, e.g., firing a blast hole with one deck and two detonators, changes in the blasting sequence can be the results of the overlapping between blasting charges. The consequences of such overlapping involve flyrock events, fragmentation and diggability problems, and other difficulties affecting the operation of the mine.

Jan 1, 2015

By A Lance McAnuff, Marcus V. van Bers, Andrew Curic

During the summers of 1992 and 1993, blasting operations were carried out to effect the crossing of two of Canada's better known game rivers, the Nipigon and Winnipeg, in connection with the completion of a third natural gas utility across north-western Ontario. The Nipigon River, crossed in 1992, involved a single fast-flowing channel while the Winnipeg River, crossed in 1993, involved three separate channels.

Jan 1, 1994

By Malcolm Scoble

The estimation of digging, ripping and blasting requirements in advance of mine production is a difficult task. The characteristics of the superficials and rock mass govern the type and intensity of ground preparation required as a prelude to loading. The incentives for optimum planning of preparation are primarily economic but also relate to mining method and equipment selection, productivity and environmental impact.

Jan 1, 1985

Fracture Control Blasting is an alternative to pre- and post-splitting or smooth wall blasting. It was developed at the University of Maryland as an attempt to overcome some of the disadvantages that occur with normal blasting practices. There are two main factors that are unique to fracture control blasting. First, it utilizes a notched or grooved borehole to initiate fractures at desired locations and secondly, it employs a very carefully selected charge so as to provide control over borehole pressure. The maximum borehole pressure must be kept between very definite limits in order to obtain initiation of fractures at locations where they are desired and yet not obtain fractures where they are not desired. When coupled with stem induced fracturing, which was developed for oil and gas well stimulation, it has been found that the charge required for fracture control can be as little as 1/40th that required for normal smooth wall blasting. The paper describes the technique of fracture control blasting and gives results of some of the field testing conducted to date.

Jan 1, 1984

By Frank Lucca

This study is based on a six month study performed for Lee County, Florida. The study was based on blasting for land development and how this type of blasting affects structures. The study is investigates peak particle velocities and the relationship to other environmental and manmade forces that affect structures. The study also explores the effect of geology on blast vibration. After completion in Lee County, the study was then continued in the quarry environment in Vermont and extremely tight blasting environment of New York City. Charge diameters were 127mm (5 inches) or less.

Jan 1, 2006

By P Albert

A wedge-shaped underwater rock plug has to be blasted in order to tap the reservoir and furnish water to a new underground powerhouse at Manicouagan-5. The paper deals with the design and engineering aspects of drilling and blasting of this plug where the topographical configuration is extremely difficult. In this study small diameter vertical holes are considered with the OD-method and a fixed platform is recommended for drilling and loading operations.

Jan 1, 1984

By Zuhair Ibrahim, Dan Tillema, Ali Reza

This paper details the investigation of a fatal explosion that occurred on April 8, 2011 at a magazine used to store fireworks in Waikele, HI. The fireworks had been confiscated by the Bureau of Immigrations and Customs Enforcement after they were informed that a container shipped to the United States contained illegal fireworks. Four groups of cardboard cartons that were marked as 1.4G (consumer fireworks) were determined to be consistent with the more explosive 1.3G type, commercial display fireworks. The subcontractor retained to destroy these fireworks stored the shipment in the subject magazine and was in the process of disassembling them on the day the explosion occurred.

Jan 1, 2014

By Greg Wyartt

"At an Australian iron ore open-cut mine, 129 separate blast patterns (consisting of 38.5 million tonnes /42.4 million US tons, equaling 28% of annual blasted tonnes) were initiated using electronic detonators. 87 patterns were designed as per site methodology using ‘vectorial’ initiation timing sequences (blast direction and relief specified only), while the remaining 42 patterns were designed with interactive initiation timing sequences - hole by hole sequencing based on the measured site specific primary shock wave (P-wave) velocity and distance between blast-holes. The intention of this project was primarily to reduce material size presented to the crushing circuit, and also to determine if productivity benefits could be obtained by the use of interactive timing."

Jan 1, 2017

By Takeo Ueda, Masashi Nakano

We have developed a new blasting system remotely controlled by an electromagnetic firing method, which has proved advantageously applicable to sites where rapid tidal current or deep water may cause serious troubles in underwater blasting operation by a conventional method.

Jan 1, 1983

By Roger E. Scholl

Data on off-site low-rise building damage from underground nuclear testing at the Nevada Test Site (NTS) of the United States Atomic Energy Commission (AEC) [The AEC has been called the United States Energy Research ant Development Administration (ERDA) since 1975, but because the data presented here were gathered between 1966 and 1970, the AEC rather than ERDA is referred to in this paper.] are available for seven large tests in the period from 1966 to 1970. The data, while sparse, provide an adequate sample for the investigation of motion-damage relationships. Damage in the study is statistically described in terms of the incidence of damage complaints, the incidence of buildings damaged, and damage cost. Using 5%damped response spectrum acceleration amplitude to characterize ground motion, the plotted data fit reasonably well with previous motion-damage relationships established from extensive data available from the 1969 RULISON underground nuclear explosion (UNE) experiment conducted in western Colorado.

Jan 1, 1976

By Marco Antonio Falquete

Conventional detonators and blasting caps make use, as igniters, of flame-shock-, andfriction-sensitive primary explosives, such as lead azide, lead styphnate, mercury fulminate, etc, most of them severe toxic and environmental contaminants. Sensitivity of primary explosives is one of the main causes of injuries and fatalities in explosives industry and in field applications. Intense research for a reliable, safe, and environmental-friendly non-primary-explosives detonator was conducted by the industry in the last years. A new detonator is presented, containing no primary explosive, employing only environmental-friendly substances while keeping reliability of performance. A series of performance tests is executed in prototypes of different output energies, including initiation by flame, shock tube, thermo tube (IBQ’s proprietary spark-generating tube, presented at 2005 ISEE Conference), energy transfer reliability, and extreme environmental conditions (according to MIL-STD 331B, test C1 standards). Results are compared, when pertinent, with standard blasting caps of different energy outputs, and with standard primary explosives.

Jan 1, 2007

By Keith Best

It has been said that when a person does something right no one remembers but when they do something wrong no one forgets. This statement, when applied to the explosives industry, has never been truer. Think about it.How many times have you seen a news crew reporting on how well a blaster is doing his/her job? Normally, all you will see is how bad things are going and how much “damage” is being done.

Jan 1, 2008

By David Hersey

The Paseo Bridge was located at the I-29/I-35/US-71 Missouri River Highway Crossing. It was built between 1952 and 1954 by Massman Construction Company. The 1,232 foot long, self-anchored suspension bridge was the longest of its type when built. On Jan. 22, 2003, a connector pin designed to allow the bridge to expand and contract during temperature cycles seized and caused a portion of the bridge deck to raise up and block traffic. This marked the beginning of the end for the old Paseo Bridge.

Jan 1, 2013

By Mauritz Kotze, Jason Furtney, Ewan Sellers, Sandy Etchells, Tom Szendrei

The development of a simple model for gas flow and burden movement has driven the need to improve our understanding of burden breakage mechanisms for single hole blasts and the interaction between multiple holes in solid and jointed rock masses. Conventional analytical understandings of the burden breakout using the elastic-tensile fracture model were studied and found to provide a breakout angle that is independent of burden in contradiction to experimental data. By considering rock fracture in terms of Mohr-Coulomb plasticity using analytical expressions from the field of cavity expansion analysis an improved relationship between breakout angle and burden is derived until the point of critical breakout at which the angle of breakout suddenly changes from between 90 degree and 100 degrees to zero. This suggests that the critical burden occurs at about 0.6 times the radial fracture zone calculated from the analytical solutions.

Jan 1, 2013

By Alvin D. Christmas

The missing link is a connector between the congested downtown area of Knoxville, Tennessee adjacent to the former World's Fair site, the I_40 I_75, and Western Avenue traffic arteries. This connecter was designed to accommodate the 37,470 motorists who presently travel through these highly congested narrow paths to be replaced by the 21.8 million dollar Henely Street Connecter. All construction and blasting was to take place while existing traffic was re_routed so as to allow access between the downtown area and the vital interstate corridor. To avoid major traffic problems, the project was to be accomplished in three phases: (1) the Western Avenue viaduct demolition; (2) two new viaducts to be constructed; (3) the open box cut at Henely Street next to the L & N Depot. Due to the past attempts by the Fort Sanders Community Home Owners group and the Historical Society to stop the Henely Street Connector, this project involved a very comprehensive blasting damage control program with special provisions of .5 inches per second measured at the foundation of the closest structure.

Jan 1, 1995

By Zheng Shuangying

The vibration effect of the buried oil pipeline caused by tunneling blasting affects the pipeline safe transportation, tunnel construction schedule and its construction cost. The dynamic response characteristic of the buried pipeline under blast loads is the foundation of designing blasting scheme as well as the prerequisite to pipeline safety. Taking the blasting engineering of Xiannvyan tunnel passing through a buried oil pipeline of the high-speed railway from Xi’an to Chengdu as the background, according to the space relation between tunnel and pipeline as well as the charge structure of V-cut blasthole, the 3D non-linear dynamic finite element model of tunnel-pipeline was established in the light of the equivalent explosive. The vibration response of the ground surface over pipeline resulting from V-cut blasting was simulated by LS-DYNA finite element program. Comparing with the measured vibration velocity waveforms in site, the accuracy and reliability of the numerical model are well verified. On the base of the simulation method, the coupling dynamic response characteristic between buried oil pipelines and soil was further studied and the Von-Mises stress distribution of pipeline wall was obtained. The safety of buried oil pipeline was quantitatively analyzed through the inside stress data of pipeline given by the simulation calculation above. The analytic results show that the maximum vertical vibration velocity of pipeline on the interface between pipeline and soil is 1.62~5.07 times as large as that of soil. When the buried pipeline is located over the tunnel and 13 m (42.6 ft) away from tunnel, the maximum vertical vibration velocity of ground surface caused by V-cut blasting with charge weight 17 kg (28.6 lb) is 3.17cm/s (1.25 in/s) and the vertical peak vibration velocity of pipeline top is about four times as the ground location directly above the pipeline. Meanwhile, the peak dynamic stress of the buried pipeline caused by blasting vibration is only 2.35% of the allowable stress of steel pipeline. The maximum superimposed stress of the blasting dynamic stress and the hoop stress produced by the pipeline internal pressure is 242.56 MPa (35 180.36), which implies that the buried oil pipeline is completely safe under the conditions of the given tunnel blasting scheme.

Jan 1, 2015