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By E. Líder, J. Pavez, J. Rivera

The application of new technologies, methodologies, and the use of new products in mining operations is a practice that is becoming more common in the industry every day, added to the new challenges and restrictions found in the operation. In the city of Tierra Amarilla, the interaction between mining operations and the community presents a constant challenge given the proximity to the community and the limitations that this presents. Explosive charge mass, in conventional blasting using traditional explosives (ANFOs, packaged explosives for example) limits the explosive charge lengths (they are reduced), impacting the explosive charge productivity. To improve the productivity of explosive charge and fragmentation, the use of low-density explosives was proposed, allowing the increase of the explosive charge length, trying to maintain the vibration levels within the established limits (2mm/s), preserving the fragmentation of the rock in the required sizes. The present study shows the results obtained from the application of low-density bulk emulsion for production blasting charges using upward and downward fan drillings. During this process, 18 blasting events were carried out, of which 8 were Up-hole loading (average density of 0.75 gr/cc) and 10 with Down-Hole loading (average density of 0.95 gr/cc). In summary, a total of 110,760 tons of ore have been broken, using low density emulsion, meeting the proposed objectives such as: 33% reduction of vibrations, 12% overbreak (within the theoretical design), P80 of 11in and 4.6% in fines.

Jan 1, 2024

By David R. Shields, Michael T. Bracher

"The $330 million (U.S.) Dana-Farber Cancer Institute’s Yawkey Center for Cancer Care (Yawkey Center) sits in the heart of Boston’s Longwood Medical Area. The Yawkey Center is a cutting-edge cancer care facility that houses Dana-Farber’s adult clinical care and clinical research programs. Standing 14 stories above grade, it includes 7 stories of underground parking extending 75 ft (23 m) below ground. The structure is on a 198 by 186 ft (60 by 57 m) site sandwiched between Dana-Farber’s 13-story Richard A. and Susan F. Smith Research Laboratories Building, the Medical Area Total Energy Plant (MATEP), Jimmy Fund Way, and Brookline Avenue, a busy four lane artery through the heart of the Longwood Medical Area. Together with Simon Design Engineering, the project structural engineer, GEI Consultants designed an innovative foundation and excavation support system to isolate the building from ground vibrations generated by the adjacent MATEP power plant. In effect, the Yawkey Center is a 21-story free-standing structure that starts 7 stories below grade.The MATEP facility provides power for 9 million sq ft (840,000 sq m) of occupied space in the medical area. There are six 32-cylinder diesel engine generators in the facility that produce low-frequency ground vibrations in the 10 Hz range, similar to the natural frequency of typical building elements. The resonant response of the Yawkey Center building structure to these ground vibrations would affect the performance of sensitive medical research equipment and cause an unacceptable environment for clinical care.The soil profile at the site consists of stiff clay, fine sand, glacial till, and bedrock consisting of hard metamorphosed conglomerate. In-situ measurements of ground vibrations performed in boreholes showed that there was little attenuation of the vibrations with depth in the soil layers overlying the bedrock, but the vibration amplitude in the bedrock was markedly lower than in the overlying soil. Based on this data, an innovative foundation system was designed to support the building on bedrock located up to 110 ft (34 m) below ground surface, while isolating it from the surrounding soil. This was done by physically separating the below-grade parking garage floors from the perimeter foundation walls to create a free-standing structure supported on the bedrock"

Jan 1, 2012

By Paul Worsey, Gerald Rupert, Mark Kirkbride

The realignment of Highway H in the proximity of Crystal Cave (Springfield MO.) required the development of a blasting program that was both economical and efficient for construction, yet ecologically safe for the cave. Three component seismographs were strategically placed underground near prominent and sensitive cave features and the vibration levels from the construction blasting continuously monitored. Peak particle velocity (PPV) values were found to obey the square root scaling law and a peak particle velocity value of 0.3 in/sec was chosen as the safe maximum limit. This value proved adequate in preserving the integrity of the cave and its features. Scaled distances for the maximum and lower values enabled blasting personnel to select explosive charge weights per delay for given distance to the cave. Delays were determined from the dominant frequencies recorded underground.

Jan 1, 1997

By Johan Finsteen Gjødvad, Mathias Jern

The paper is part of the ongoing work of the Environmental committee of EFEE. To assist the European experts working with explosives one of the aims is to improve the common knowledge of similarities and differences between national legislation, standards or guidelines on vibration monitoring and other environmental monitoring during blasting in Europe and abroad. This has been done by use of an online survey through the most of 2018. Questions have been raised on vibration monitoring during blasting. The existence of norms, guidelines or standards and how they are used. Even though the questions have been kept at a high level they are formed to try to map the different national standards use of such things as frequency, guidance on monitoring position, distinction between different types of structures, requirement to the equipment and more. Furthermore a few initial questions have been raised on other environmental monitoring relevant for blasting. The respondents are national, cooperate or individual members of EFEE. The answers are experts in the use of explosives and vibration-monitoring in their respective countries. More than 60 have answered the questionnaire from 29 different countries. Mainly European as well as other nations including India, Israel, Nigeria, Saudi Arabia, UAE, USA, Greenland and Hong Kong. By analysing the incoming answers, the differences and similarities in vibration monitoring of the respondents has been clarified and mapped. Where possible other environmental monitoring has also been analysed. Where needed the different guidelines, standards and regulations have been visited to verify the answers and further elaborate on the comparison.

By Johan Finsteen Gjodvad, Mathias Jern

The paper is part of the ongoing work of the Environmental committee of EFEE. To assist the European experts working with explosives one of the aims is to improve the common knowledge of similarities and differences between national legislation, standards or guidelines on vibration monitoring and other environmental monitoring during blasting in Europe and abroad.

Feb 1, 2020

By Francisco Sena Leite, Pedro Brito, Auã Kiahla, Raquel Carvalhinha, Tomi Kouvonen, Vinicius Miranda

Shockwaves that generate vibration in the surrounding environment of a blast, are one of the most important factors to control drill & blasting works near delicate buildings as well as in sensitive structures (wall control). On top of the damage to the buildings themselves, sensitive equipment such as computers, measurement apparatus and medical devices can be also compromised. The most commonly measured values from vibration are PPV (peak particle velocity), acceleration and displacement. Some devices and techniques have been developed in the last decades to measure the impacts of these vibratory phenomena. This information can be used to predict levels of vibration for future blasts and improve their quality of design using the attenuation law. From traditional studies to modern seismographs, a range of solutions are used for this propose. The main problem of applying this kind of technology is the high cost associated with each measurement device. In order to measure the ground vibration using new technologies while lowering the cost, a device has been developed using a microcontroller and electronic sensors commonly found on the market. This new equipment was tested side by side with traditional seismographs and the results were sent to a server for analysis. After several blasts, the necessary data was generated for the validation of the prototype. Through numerical mathematical processing (Taylor’s approach and numerical derivation) the original data supplied by the accelerometer’s sensors was transformed into velocity and, after the data mining, a statistics residue analysis was applied in order to evaluate if the data from the prototype and from the traditional seismographs were similar. The data from each system was used to estimate the attenuation law and the results are shown in this paper.

By Auã Kiahla, Tomi Kouvonen, Vinicius Miranda

Through numerical mathematical processing (Taylor’s approach and numerical derivation) the original data supplied by the accelerometer’s sensors was transformed into velocity and, after the data mining, a statistics residue analysis was applied in order to evaluate if the data from the prototype and from the traditional seismographs were similar. The data from each system was used to estimate the attenuation law and the results are shown in this paper

Feb 1, 2020

By Nadir Plasencia, Rogerio: Neves Mota

The evaluation of vibrations induced to build structures is one of the main concerns when dealing with blast works. EDP, the main Portuguese producer of electricity is presently incrementing energy production in some old hydropower dams by installing new production plants. The need for not disrupting production during the upgrading works causes some concerns related with vibrations induced to the production engines. Vibration estimation was performed in two of these dams, constructed in a granite environment, by performing controlled blasts. For each dam site, some vibration transmissivity laws were developed with the fitting process.

Jan 1, 2008

By Shi Hongchao, Zou Zou Xinkuan, Zhang Jichun

As drilling and blasting is carried out in an urban tunnel, which is adjacent to an existing building or structure, the balance between blasting-induced vibration reduction and drivage efficiency is a most important issue that must be resolved properly. Therefore, a new cut blast method named Stepped V-cut millisecond blasting (SV-cut) was developed by optimizing the most common used Vertical V-cut blasting method (V-cut). The most significant features of SV-cut lie in the utilization of sublevel interval charging structure and millisecond delay blasting technology in cut hole and the cut-cavity formed from outside to inside sequentially. SV-cut provides advantages of high borehole using ratio, low vibration level, and satisfied advance per attack. Based on the principal of millisecond blasting, the rock fragmentation process and the vibration reduction mechanism of SV-cut are analyzed. Determining methods of blasting parameters, which do have significant effect on vibration intensity and cut-cavity formed quality, are proposed according to the forming requirement of both outer and inner cut-cavity and vibration reduction. In order to compare the performance between SV-cut and V-cut, field blasting experiments were performed in the blasting engineering of Yamalike twin-arc tunnel, which closely passes over aged parallel tunnels. Blasting results show that SV-cut blasting is proven as an effective tunnel blasting method for both increasing blasting effects and decreasing blasting vibration. Comparing SV-cut with V-cut, the SV-cut can increase blasting drivage about 8.5% and reduce the vibration intensity induced by cut hole blasting 30% at least.

Jan 1, 2015

By Bryan Papillon, Karl Christopherson

In order to improve vibrations from quarry blasting, a new technique and timing pattern was established and applied to the particular geology. By shooting a single representative borehole one full second ahead of the production blast, a signature waveform can be isolated and analyzed. Multiple productionsignature blasts were performed. Encroaching residences require quarries to adjust their blasting techniques to reduce vibrations and raise frequencies. A signature hole inherently poses problems to quarries. Blasting one single hole from a production bench poses safety issues to wall stability; vibration issues to close neighbors; and budget issues to the quarry operator. Results showed that the new timing pattern reduced vibrations through timing optimization without a loss in quarry production. Therefore, this technique of vibration analysis employing a production-signature hole is successful in creating a timing pattern that meets the quarry’s goals.

Jan 1, 2008

By D P. Blair

Rio Tinto’s Hope Downs Operations are currently mining iron ore in their South Central Pit. Prior to the commencement of mine operations, Hope Downs carried out an extensive archaeological investigation and identified an ancient rock shelter lying within the proposed mine boundaries. The site is significant to the traditional owners/custodians of the land in this part of the Pilbara, and thus the final pit design was changed to preserve the rock shelter, which now lies 30 m outside the mine boundary. In order to further preserve this ancient dwelling from blast-induced damage, blast design procedures were improved over time to minimise the vibration impact when blasting close to the shelter. Blasting and vibration monitoring commenced in May 2008 using pyrotechnic delay sequences and normal-direction firing. In October 2009 electronic delays were used to reverse-fire blasts close to the shelter in order to create a damage zone between the initiating holes and the rock shelter. A detailed statistical analysis of the vibration data shows a reduction in the higher levels of vibration for blasts fired after October 2009, which is most likely caused by the created damage zone. In May 2010, a site-specific vibration model was developed and implemented, and based on Monte Carlo waveform superposition. This model was used to give a further insight and improvement to the blast delay sequences when blasting close to the shelter. However, such models are expensive to implement and have limitations, which reduces their potential for estimating the probability of getting an excessive vibration due to a given blast design. In this regard, it is more realistic and significantly less expensive to use a recently developed probabilistic analysis based on simple charge weight scaling. This analysis shows that there was a higher probability of exceeding prescribed vibration limits at the rock shelter for blasts fired before October 2009 than there was for blasts fired after October 2009.

Nov 8, 2011

By W. Stahl, K. Keller

In addition to classifying bulk material, vibration screens are commonly used in dewatering. However, the lack of a comprehensive physical theory of dewatering often leads to difficulties in the design and operation of the vibration screens. First, in this report, the dewatering of bulk material are shown based on a physical model. Because of tile oscillatory motion of the liquid in the bulk, the inertial force of the accelerated liquid and the dripping of water out of the bulk or screen must be taken into special consideration. The physical model put forward shows the effect of the various operations parameters of dewatering screens. A comparison between dewatering theory and practice are shown by measurements using coal, limestone, etc. Dewatering measurements conducted on a vibration screen demonstrated that different vibration frequencies and rates of acceleration lead to different residual moistures. Finally, the possibility of improving vibration dewatering is described.

Jan 1, 1998

By Werner Stahl, Karsten Keller

Vibration screens are commonly used not only in classifying bulk material but also in dewatering it. The lack of a comprehensive physical theory of dewatering often leads to difficulties in the design and operation of the vibration screens. Firstly, the dewatering of bulk material will be shown, based on a physical model. Because of the oscillatory motion of the liquid in the bulk, the inertial force of the accelerated liquid and the dripping of water out of the bulk or screen must be taken into special consideration. The physical model put forward shows the effect of the various operations parameters of dewatering screens. The comparison between dewatering theory and practice will be shown by measurements using coal, limestone, etc. Dewatering measurements, which have been conducted on a vibration screen, demonstrate that different vibration frequencies and rates of acceleration lead to different residual moistures. Finally, the possibilities of improving vibration dewatering will be described.

Jan 1, 1995

By Y. Zeng

Experiments were performed under batchwise wet grinding conditions with dolomite mineral. The vibration signal was received by an accelerometer and transmitted to a mini-processor. The signal was first stored on a digital tape recorder (OAT) in voltage format during the grinding tests. The original signal was then re-sampled and converted into data format for IBM or compatible personal computer by a digital oscilloscope. The root-mean-square (RMS) and power spectrum was estimated on the time-domain vibration signal. A partial correlation analysis was applied to the frequency-domain signal to detect the non-zero correlation between the frequency bands and the operating parameters. A multiple stepwise regression was used to locate the key frequency bands for describing a particular operating parameter. After vibration analysis, the operating parameters in grinding, for example, the mill speed, the powder filling, the pulp density, the pulp temperature and the particle size were found to be strongly correlated with a few frequency bands. The grinding process could therefore be monitored using the vibration signal.

Jan 1, 1992

By P. -É. Boileau, M. Smets, T. Eger, J. Boutin

Long-haul dump (LHD) vehicles used in underground mining are known to expose workers to important levels of whole-body vibration1. These vehicles are generally designed without suspension and may be categorized as small or large LHDs depending on whether their respective load capacities are lower or larger than 3.5 cubic yards. While the majority of older vehicles are equipped with a rigid or unsuspended seat, more recent LHDs often incorporate a suspension seat. The objective of this study was to define the vibration spectral characteristics of most commonly encountered large and small LHD vehicles operating in mining operations. This was done in an effort to categorize the vehicles in terms of vibration spectral classes to be reproduced on a laboratory whole-body vibration simulator to assess the vibration attenuation performance of a typical LHD suspension seat. Methods Vertical vibration measured at the seat attachment point of 8 small and 8 large LHD vehicles operating underground in typical mining operations under loaded and unloaded conditions was considered as the basis for defining the spectral classes. By regrouping the data collected for each LHD vehicle size and load condition, the overall distribution of acceleration power spectral density (PSD) of measured floor vibration was determined over the 0.5 to 20 Hz frequency range. Mean and envelopes of maximum and minimum values of PSD spectra were computed to define the spectral classes, along with the corresponding values of frequency weighted rms acceleration determined in accordance to the ISO 2631-1 standard2. These spectra were further used to calculate the displacements needed to drive a whole-body vibration simulator consisting of a platform supported by two servo-hydraulic actuators having a total stroke of ±100 mm. For validation purposes, the vibration acceleration spectra measured on the simulator were compared with the target spectra representing the spectral classes. Finally, the vibration transmissibility characteristics of a typical suspension seat were determined under sine sweep excitation using both a rigid mass load and a human subject having a mass of 62 kg and 85 kg, respectively. The SEAT value, representing the ratio of seat to base frequency-weighted rms acceleration, was further measured under each of the defined LHD vibration spectral classes by loading the seat with an 85 kg subject. Tests were repeated three times and the mean SEAT values were determined to assess the seat’s ability to reduce exposure to whole-body vibration in LHD vehicles. Results Three spectral classes applicable to both loaded and unloaded conditions were defined as shown in Figure 1: one for large and two for small LHDs. The influence of load on frequency-weighted rms acceleration was found to be negligible for large and Class I small LHDs, while a shift of the peak acceleration PSD to lower frequencies was noted for the loaded vehicles. The influence of load was found to be more important for Class II small LHDs. Table 1 provides a

Jan 6, 2006

By Gordon M. Matheson, Douglas A. Anderson, David K. Miller

"Traditionally, analysis of vibrations from blasting has been focused on peak particle velocity fordetermining the likelihood of both annoyance and damage. The US Bureau of Mines, in RI 8507,indicated the importance of frequency in vibration. Methods of controlling the vibration by reducingthe vibration concentrated in certain frequency bands using delays have been successful over the past decade."

Jan 1, 1997

By L. Don Leet

Abstract Earthborne vibrations from blasting and other sources, including rock bursts, can now be recorded effectively. The nature and magnitude of vibrations from various sources have been investigated and certain applications of the knowledge thus gained have been made. Vibrations from blasting have been measured on special equipment over a range from an electric blasting cap at a few feet, through the largest quarry shot in history to date ( 1,-362,985 lb.), to the first atomic bomb, in uew Mexico on July 16th, 1945. Laws relating amount of explosive to amount of vibration at different distances have been developed and tested. Special studies have been made of the effects of vibrations on buildings, particularly from the standpoint of possible structural damage. Recorded vibrations are used to study the effects of modern short-period delay shooting. It ?has been found that short-period delay firing is extremely effective in reducing vibrations under the right conditions, but with certain limitations. In quarry shooting, there appears to be a minimum number of holes below which vibrations are not appreciably reduced by short-period delay firing. In several instances this minimum has been near 7. Vibrations in the ground from rock bursts and the effects of mining in stresesd ground have been studied both underground and on the surface in a search for a rock burst warning system. Introduction Earthborne vibrations from blasting and other sources, including rock bursts, can now be recorded effectively. Analyses of blasting records have been yielding increasing funds of information of practical as well as theoretical interest. The nature and magnitude of the vibrations have been investigated with special reference to their effects on structures.

Jan 1, 1951

Perform laboratory tests to measure the vibration attenuation characteristics of off-road vehicle operator seats for various types of seat suspensions, cushions, and seat adjustment settings. Background A study was conducted by the U.S. Bureau of Mines to determine the probability of whole-body vibration (WBV) exposure for a large class of off-road machinery operating in surface coal mines. The study determined that mere than 40 pct of off-road equipment operators were exposed to WBV exceeding the standard fatigue-decreased-proficiency (FDP) level defined by the International Standards Organization in its guideline ISO standard 2631. The tire-terrain interaction of a moving vehicle generates vibrations that are transmitted through the ve¬hicle suspension, cab mounting, and seat. The final point of transmission of vehicle vibration to the operator is through the scat. A seat that provides good vibration isolation and allows good vehicle control is of prime importance to operator safety and health.

Jan 1, 1993

By Vibration Research Group, Natasha K. Lee Shee, Tammy R. Eger, James P. Dickey, Paul-Émile Boileau, Lana M. Trick, Michele L. Oliver

Introduction Industrial exposure to whole-body vibration is associated with injury and discomfort. Certain industries, notably mining, construction, and forestry, involve complex 6 degrees of freedom vibration. Laboratory-based studies of vibration are essential for controlled and systematic evaluation of the human responses to vibration2. The purpose of this pilot study was to evaluate whether the duration of the vibration exposure, and rest between vibrations, significantly influence the subjective ratings of comfort during laboratory-based studies of vibration. Methods Subjects: The cumulative vibration dose was calculated, and was below the health guidance caution zone recommended by International standards3. The experimental procedures were approved by the University of Guelph Research Ethics Board. Ten adult subjects participated in this pilot experiment. All subjects completed the entire experimental paradigm; no subjects complained of pain during or after the experiment. Experimental Design: The experiment consisted of four blocks of vibration exposures; either 15 or 20 seconds of vibration (1 df:Z axis, 3 df:XY plane, 3df:YZ plane, or 6 df) alternating with either 5 or 10 seconds rest. The order of presentation of the four blocks was randomized. Each of the blocks was composed of 37 individual sinusoidal vibration exposures in randomized sequence. This abstract focused on ten identical trials, (6.3 Hz vertical vibration, 0.55 m/s2 RMS) interspersed within each block, in order to assess whether the subjects’ comfort ratings systematically varied between the 15 or 20 vibration exposures, the 5 or 10 second rest between vibrations, or within each block. The experiment involved 43 minutes of vibration within the 62 minute experiment. Vibration Apparatus: A commercial parallel robotic platform was used to apply the specific vibration exposures (R2000, Parallel Robotics Systems Corporation, Hampton, New Hampshire). The subjects sat on a passenger seat from a 1992 Honda Accord that was rigidly mounted to the robotic platform (Figure 1). This robotic system performed the specific vibration exposures operating under closed-loop displacement control. A custom-written Matlab program automated the testing sequence.

Jan 6, 2006

By Paul McAnuff, Alastair Grogan

In Canada, the only vibration regulations which apply across the entire country are intended to protect fish spawning areas. The Provinces and Territories regulate mines and quarries, and are responsible for setting vibration and airblast regulations. Some Provinces have set specific regulations, while others leave these restrictions to the mines inspectors who can set limits on a case by case basis. For the most part, it is left to individual municipalities to regulate blast vibrations and airblast from other blasting activities, which differ from jurisdiction to jurisdiction, and in some cases are not enforced. Blasters working in different jurisdictions have to be aware of the applicable regulations for the area they are working.

Jan 1, 2005