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1.
Enhanced demand for coal and minerals in the country has forced mine operators for mass production through large opencast mines. Heavy blasting and a large amount of explosive use have led to increased environmental problems, which may have potential harm and causes a disturbance. Ground vibrations generated due to blasting operations in mines and quarries are a very important environmental aspect. It is clear that a small amount of total explosive energy is being utilized in blasting for breakage of rock mass, while the rest is being wasted. The amount of energy which is wasted causes various environmental issues such as ground vibrations, air overpressure, and fly rock. Ground vibrations caused by blasting cannot be eliminated entirely, yet they can be minimized as far as possible through a suitable blasting methodology. A considerable amount of work has been done to identify ground vibrations and assess the blast performance regarding the intensity of ground vibrations, i.e., peak particle velocity and frequency spectrum. However, not much research has done into reducing the seismic energy wasted during blasting leading to ground vibrations. In this paper, the blast-induced ground vibrations in three orthogonal directions, i.e., transverse, vertical, and longitudinal, were recorded at different distances using seismographs. An attempt has been made for the estimation of the percentage of explosive energy dissipated in the form of seismic energy with electronic and non-electric (NONEL) initiation system. signal processing techniques with the help of DADiSP software is used to study the same. 相似文献
2.
An extensive multivariate analysis procedure for prediction of blast fragmentation distribution is presented. Several blasts performed in various mines and rock formations in the world are brought together and evaluated. Blast design parameters, the modulus of elasticity, in situ block size are considered to perform multivariate analysis. The hierarchical cluster analysis is used to separate the blasts data into different groups of similarity. Group memberships were checked by the discriminant analysis. The multivariate regression analysis was applied to develop prediction equations for the estimation of the mean particle size of muckpiles. Two different prediction equations were developed based on the rock stiffness. Validation of the proposed equations on various mines is presented and the capability of the prediction equations was compared with one of the most applied fragmentation distribution models appearing in the blasting literature. Prediction capability of the proposed models was found to be strong. Diversity of the blasts data used is one of the most important aspects of the developed models. The models are not complex and suitable for practical use at mines. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
3.
Blasting has been the most frequently used method for rock breakage since black powder was first used to fragment rocks, more than two hundred years ago. This paper is an attempt to reassess standard design techniques used in blasting by providing an alternative approach to blast design. The new approach has been termed asymmetric blasting. Based on providing real time rock recognition through the capacity of measurement while drilling (MWD) techniques, asymmetric blasting is an approach to deal with rock properties as they occur in nature, i.e., randomly and asymmetrically spatially distributed. It is well accepted that performance of basic mining operations, such as excavation and crushing rely on a broken rock mass which has been pre conditioned by the blast. By pre-conditioned we mean well fragmented, sufficiently loose and with adequate muckpile profile. These muckpile characteristics affect loading and hauling [1]. The influence of blasting does not end there. Under the Mine to Mill paradigm, blasting has a significant leverage on downstream operations such as crushing and milling. There is a body of evidence that blasting affects mineral liberation [2]. Thus, the importance of blasting has increased from simply fragmenting and loosing the rock mass, to a broader role that encompasses many aspects of mining, which affects the cost of the end product. A new approach is proposed in this paper which facilitates this trend 'to treat non-homogeneous media (rock mass) in a non-homogeneous manner (an asymmetrical pattern) in order to achieve an optimal result (in terms of muckpile size distribution).' It is postulated there are no logical reasons (besides the current lack of means to infer rock mass properties in the blind zones of the bench and onsite precedents) for drilling a regular blast pattern over a rock mass that is inherently heterogeneous. Real and theoretical examples of such a method are presented. 相似文献
4.
The purpose of blasting operations is rock fragmentation. Blasting is a key component in the overall rock fragmentation system
- the first element of the ore extraction process. It provides appropriate rock material granulation or size that is suitable
for loading and transportation. However, in spite of many advantages explosives have, their usage may cause environmental
problem such as seismic vibration. One of the solutions to this particular problem may be application of an artificial screen
as a barrier to the seismic wave path. The results of experimental research on the artificial screen concept, its characteristics
and role in attenuation of seismic effects generated by blasting are presented. The experiment is based on two physical phenomena:
(1) the size and degree of discontinuity and (2) the reflection and refraction of seismic waves. More than 1,500 laboratory
measurements were conducted with different combinations of screen sizes, positions of the screen to blasting source, and intensities
of blasting impulses. The results of the study show reduction of generated vibrations up to 58% by employment of artificial
screens. 相似文献
5.
Empirical approaches for predicting fragmentation from blasting continue to play a significant role in the mining industry in spite of a number of inherent limitations associated with such methods. These methods can be successfully applied provided the users understand or recognize their limitations. Arguably, the most successful empirical based fragmentation models have been those applicable to surface blasting (e.g., Kuz-Ram/Kuznetsov based models). With widespread adoption of fragmentation assessment technologies in underground operations, an opportunity has arisen to extend and further develop these type approaches to underground production blasting.
This paper discusses the development of a new fragmentation modelling framework for underground ring blasting applications. The approach is based on the back-analysis of geotechnical, blasting and fragmentation data gathered at the Ridgeway sub level caving (SLC) operation in conjunction with experiences from a number of surface blasting operations.
The basis of the model are, relating a peak particle velocity (PPV) breakage threshold to a breakage uniformity index; modelling of the coarse end of the size distribution with the Rosin-Rammler distribution; and modelling the generation of fines with a newly developed approach that allows the prediction of the volume of crushing around blastholes.
Preliminary validations of the proposed model have shown encouraging results. Further testing and validation of the proposed model framework continues and the approach is currently being incorporated into an underground blast design and analysis software to facilitate its application. 相似文献
This paper discusses the development of a new fragmentation modelling framework for underground ring blasting applications. The approach is based on the back-analysis of geotechnical, blasting and fragmentation data gathered at the Ridgeway sub level caving (SLC) operation in conjunction with experiences from a number of surface blasting operations.
The basis of the model are, relating a peak particle velocity (PPV) breakage threshold to a breakage uniformity index; modelling of the coarse end of the size distribution with the Rosin-Rammler distribution; and modelling the generation of fines with a newly developed approach that allows the prediction of the volume of crushing around blastholes.
Preliminary validations of the proposed model have shown encouraging results. Further testing and validation of the proposed model framework continues and the approach is currently being incorporated into an underground blast design and analysis software to facilitate its application. 相似文献
6.
The Use of Lagrange Diagrams in Precise Initiation Blasting. Part I: Two Interacting Blastholes 总被引：2，自引：0，他引：2
Using the concept of Lagrange diagrams this contribution details the calculation of the delay time between blastholes in a row and rows of blastholes with respect to precise initiation timing within the new advanced blasting technology which is based on the use of electronic detonators. After introducing the representations of stress waves and cracks, this contribution focuses on the role of stress wave interaction in optimal fragmentation in surface blasting and bench blasting. Part I of the paper considers two interacting blast-holes, Part II will be devoted to three or more out of plane interacting blastholes, whereas Part III will treat the interaction with a free face such as encountered in bench blasting. A few simplifying assumptions have been made in this paper with respect to the rock mass as well as the mechanical treatment. The essential assumptions include that the rock mass is treated as a continuum with finite tensile and compressive strength and the effects of structural geology are not taken into account. In addition, the analysis in Part I is simplified by two 'educational' assumption, that all waves are plane (i.e., one-dimensional) waves and three-dimensional effects of finite size blastholes and charges are not taken into account. This contribution will also show that knowledge in wave propagation and fracture mechanics is essential for the successful application of the new blasting technique in industry. In particular, the delay time, the wave speeds in the rock mass, the shape of the wave pulse and the acoustic impedance mismatch (not considered in this paper) have become decisive parameters in advanced blasting. Utilizing the wave speed and wave shapes of detonations, large scale tests in various countries (Australia, Chile, etc.) have shown that optimal delay timing requires shorter delay times in conjunction with allowing for a wider drilling pattern and the use of a grossly reduced amount of explosives , i.e., a lower powder factor. This seemingly contradictory arrangement is fully justified by using scientific principles in blasting, and converting blasting from an art to a scientific discipline . 相似文献
7.
Explosives are still the cheapest source of breaking rock in the mining or tunnelling operation and can be applied in varying geological conditions. It generates various troubles such as ground vibration, air overpressure, and fly rocks. It is well known that the maximum charge per delay (MCPD) has to be optimum for safe blasting and can be achieved through trial blasts, which is a complicated and costly process. Therefore, it is required to reduce the number of trial blasts. In this study, a total of 18 blasts were conducted in an underground coal mine and were simulated using similar ground conditions using Ansys software. The Peak particle velocity values obtained in the mines and through the models were compared. The error in PPV found between the actual and predicted by simulation is less than 15%. It can help us design the MCPD in rock excavation operations, visualise damages using simulation in Ansys software, and economical compared to field trials.
相似文献8.
M. G. Şenyur 《Rock Mechanics and Rock Engineering》1998,31(3):181-196
Summary The purpose of this study is to statistically correlate the fragmentation gradient () and average fragment size () with the blasting test parameters for rock masses having different characteristics. Blasting tests were conducted in limestone
exposed during the highway construction between Tarsus and Pozanti (Turkey). Three test sites were classified as poor rock,
good rock, and very good rock according to their RMR ratings. The selected blasting test parameters that affect the degree
of fragmentation were burden, bench height and ANFO charge. After each blast, the muckpiles were screened and fragment size
distribution graphs were plotted. Yates' method was applied for experimental design and analysis of variance. The single and
combined effects of blasting test parameters were analyzed through the Yates' tables and significant and non-significant treatment
combinations were determined for different rock masses. Some conclusions drawn from this research are: 1. The increase of
RMR ratings promotes fragmentation, hence, increases blasting efficiency. 2. In rock masses of low RMR ratings, the volume
of broken material is large, but fragmentation into small sizes is low. The opposite is true for rock masses of high RMR ratings.
3. The length of charge column is the significant factor affecting the average fragment size regardless the type of rock mass
and is more significant in very good quality rock mass. 相似文献
9.
J. Kemeny E. Mofya R. Kaunda P. Lever 《Fragblast: International Journal for Blasting and Fragmentation》2002,6(3):311-320
One of the fundamental requirements for being able to optimise blasting is the ability to predict fragmentation. An accurate blast fragmentation model allows a mine to adjust the fragmentation size for different downstream processes (mill processing versus leach, for instance), and to make real time adjustments in blasting parameters to account for changes in rock mass characteristics (hardness, fracture density, fracture orientation, etc). A number of blast fragmentation models have been developed in the past 40 years such as the Kuz-Ram model [1]. Fragmentation models have a limited usefulness at the present time because: 1. The input parameters are not the most useful for the engineer to determine and data for these parameters are not available throughout the rock mass. 2. Even if the input parameters are known, the models still do not consistently predict the correct fragmentation. This is because the models capture some but not all of the important rock and blast phenomena. 3. The models do not allow for 'tuning' at a specific mine site. This paper describes studies that are being conducted to improve blast fragmentation models. The Split image processing software is used for these studies [2, 3]. 相似文献
10.
Prediction of ground vibration due to quarry blasting based on gene expression programming: a new model for peak particle velocity prediction 总被引：1，自引：1，他引：0
R Shirani Faradonbeh D Jahed Armaghani M. Z. Abd Majid M. MD Tahir B. Ramesh Murlidhar M. Monjezi H. M. Wong 《International Journal of Environmental Science and Technology》2016,13(6):1453-1464
Blasting is a widely used technique for rock fragmentation in opencast mines and tunneling projects. Ground vibration is one of the most environmental effects produced by blasting operation. Therefore, the proper prediction of blast-induced ground vibrations is essential to identify safety area of blasting. This paper presents a predictive model based on gene expression programming (GEP) for estimating ground vibration produced by blasting operations conducted in a granite quarry, Malaysia. To achieve this aim, a total number of 102 blasting operations were investigated and relevant blasting parameters were measured. Furthermore, the most influential parameters on ground vibration, i.e., burden-to-spacing ratio, hole depth, stemming, powder factor, maximum charge per delay, and the distance from the blast face were considered and utilized to construct the GEP model. In order to show the capability of GEP model in estimating ground vibration, nonlinear multiple regression (NLMR) technique was also performed using the same datasets. The results demonstrated that the proposed model is able to predict blast-induced ground vibration more accurately than other developed technique. Coefficient of determination values of 0.914 and 0.874 for training and testing datasets of GEP model, respectively show superiority of this model in predicting ground vibration, while these values were obtained as 0.829 and 0.790 for NLMR model. 相似文献
11.
G. D. Just 《Rock Mechanics and Rock Engineering》1973,5(3):151-162
SummaryThe Application of Size Distribution Equations to Rock Breakage by Explosives Size distribution equations can be used to describe the degree of fragmentation produced by explosive rock breakage. This paper describes the results of small scale blasting experiments and the derivation of equations to relate size distributions to blasting design parameters. The application and relevance of these techniques to large scale blasting operations is also discussed.With 7 Figures 相似文献
12.
E. Widzyk-Capehart P. Lilly 《Fragblast: International Journal for Blasting and Fragmentation》2002,6(2):151-168
Blasting is the primary comminution process in most mining operations. This process involves the highly complex and dynamic interaction between two main components. The first is the detonating explosive and the second is the rock mass into which the explosive is loaded. The mechanical properties of the rock material (such as dynamic strength, tensile strength, dynamic modulus and fracture toughness) are important considerations in understanding the blasting process. However, it is the characteristics of the geological defects (joints, foliation planes, bedding planes) within the rock mass that ultimately determine how effectively a blast performs in terms of fragmentation, all else being equal. The defect characteristics include, but are not limited to, their orientation, spacing, and mechanical properties. During the blasting process, some of the geotechnical characteristics of the rock mass are substantially changed. From the blasting outcome point of view, the most notable and important is the change in fragment size distribution that the rock mass undergoes. The pre-blast in situ defect-bounded block size distribution is transformed into the post-blast muckpile fragment size distribution. Consequently, it is fundamental to our understanding of and ability to predict the blasting process that both the blastability of a rock mass and its transformation into the fragment size distribution can be appropriately quantified. 相似文献
13.
Prediction of Backbreak in Open-Pit Blasting Operations Using the Machine Learning Method 总被引：1，自引：1，他引：0
Backbreak is an undesirable phenomenon in blasting operations. It can cause instability of mine walls, falling down of machinery, improper fragmentation, reduced efficiency of drilling, etc. The existence of various effective parameters and their unknown relationships are the main reasons for inaccuracy of the empirical models. Presently, the application of new approaches such as artificial intelligence is highly recommended. In this paper, an attempt has been made to predict backbreak in blasting operations of Soungun iron mine, Iran, incorporating rock properties and blast design parameters using the support vector machine (SVM) method. To investigate the suitability of this approach, the predictions by SVM have been compared with multivariate regression analysis (MVRA). The coefficient of determination (CoD) and the mean absolute error (MAE) were taken as performance measures. It was found that the CoD between measured and predicted backbreak was 0.987 and 0.89 by SVM and MVRA, respectively, whereas the MAE was 0.29 and 1.07 by SVM and MVRA, respectively. 相似文献
14.
Stochastic Modeling Approach for the Evaluation of Backbreak due to Blasting Operations in Open Pit Mines 总被引：2，自引：0，他引：2
Backbreak is an undesirable side effect of bench blasting operations in open pit mines. A large number of parameters affect backbreak, including controllable parameters (such as blast design parameters and explosive characteristics) and uncontrollable parameters (such as rock and discontinuities properties). The complexity of the backbreak phenomenon and the uncertainty in terms of the impact of various parameters makes its prediction very difficult. The aim of this paper is to determine the suitability of the stochastic modeling approach for the prediction of backbreak and to assess the influence of controllable parameters on the phenomenon. To achieve this, a database containing actual measured backbreak occurrences and the major effective controllable parameters on backbreak (i.e., burden, spacing, stemming length, powder factor, and geometric stiffness ratio) was created from 175 blasting events in the Sungun copper mine, Iran. From this database, first, a new site-specific empirical equation for predicting backbreak was developed using multiple regression analysis. Then, the backbreak phenomenon was simulated by the Monte Carlo (MC) method. The results reveal that stochastic modeling is a good means of modeling and evaluating the effects of the variability of blasting parameters on backbreak. Thus, the developed model is suitable for practical use in the Sungun copper mine. Finally, a sensitivity analysis showed that stemming length is the most important parameter in controlling backbreak. 相似文献
15.
Naeim Ghaeini Mojtaba Mousakhani Hassan Bakhshandeh Amnieh Ahmad Jafari 《Arabian Journal of Geosciences》2017,10(18):409
One of the most important aims of blasting in open pit mines is to reach desirable size of fragmentation. Prediction of fragmentation has great importance in an attempt to prevent economic drawbacks. In this study, blasting data from Meydook mine were used to study the effect of different parameters on fragmentation; 30 blast cycles performed in Meydook mine were selected to predict fragmentation where six more blast cycles are used to validate the results of developed models. In this research, mutual information (MI) method was employed to predict fragmentation. Ten parameters were considered as primary ones in the model. For the sake of comparison, Kuz-Ram empirical model and statistical modeling were also used. Coefficient of determination (R 2), root mean square error (RMSE), and mean absolute error (MAE) were then used to compare the models. Results show that MI model with values of R 2, RMSE, and MAE equals 0.81, 10.71, and 9.02, respectively, is found to have more accuracy with better performance comparing to Kuz-Ram and statistical models. 相似文献
16.
Over the past 18 months the De Beers Consolidated Mines Ltd operations have made a concerted effort to move away from using the traditional shock tube initiating systems. These systems are being systematically replaced by the use of electronic delay detonators (EDD). Various trials were conducted in both host rock and kimberlite rock masses to improve tunnel advance as well as to optimise delay timing during trough openings [1-3]. The high cost of EDD's, when compared with traditional initiation systems, led to a number of detailed studies being conducted on the mines where EDD's were being used. These studies aimed to quantify the additional benefits when blasting with electronic detonators. The studies showed that the change was justified on the basis of increased quality control and reliability gained through the use of EDD's. However, these benefits attract other related benefits, like fragmentation control, and backbreak reductions. When compared to the shock tube initiating systems the increased development face advance and the reduction of oversize during production blasting using EDDs, compared favourably to the less costly systems. As blasting engineers gained experience and confidence in the use of the system bigger blasts were initiated in mass under-cut blasts and slot raise development, by using multiple hole firing and second delay periods between holes. In the open pit and sublevel open stope mining methods the control of the fragmentation distribution and the effect of the mass of explosive detonated during a blast is detrimental to the loading and hauling production rates and the stability of the rock mass behind the blast. With a stable rock mass the bench cutting can be executed to establish steeper overall slope angles leading to large cost savings due to a reduction in waste stripping. It is the purpose of this paper to indicate through quantification that the use of the EDDs as an initiating system improves all-round blasting performances and assists in meeting customer requirements. The customer being the ore treatment plant. 相似文献
17.
The influence of air deck blasting on blast performance and blast economics and its feasibility has been studied in the production blasting of soft and medium strength sandstone overburden rocks in an open pit coal mine in India. The air deck blasting technique was very effective in soft and medium strength rocks. Its main effects resulted in reducing fines, in producing more uniform fragmentation and in improving blast economics. The fines were reduced by 60–70% in homogeneous sandstones. Oversize boulders were reduced by 80% and shovel loading efficiency was improved by 20–40% in blocky sandstones. The explosive cost was reduced by 10–35% dependent on the type of rock mass. Throw, backbreak and ground vibration were reduced by 10–35%, 50–80% and 30–94% respectively. For a particular rock mass and blast design environment, air deck length (ADL) significantly influenced the fragmentation. ADL as represented by air deck factor (ADF) in the range of 0.10–0.35 times the original charge length (OCL) produced optimum results. ADF beyond 0.35 resulted in poor fragmentation and in inadequate burden movement. 相似文献
18.
岩石磨蚀性的试验研究 总被引：1，自引：0，他引：1
岩石磨蚀性的试验研究在探矿工程以及其它采掘工程中都具有重要的意义。 本文详细地叙述了一种测定岩石磨蚀性的方法。作者利用钻铣磨床改装而成的装置,在规定的条件下（轴压力15kgf,转速400r/min,时间10min）,测定了25种岩石的磨蚀性指标;同时,还测定了在这些岩石中一字形钎头的磨次进尺、岩石的石英含量及粒度、岩石的压入硬度;并借助微机进行了数据处理与回归分析,对它们之间的相关性进行了评价。 实验与分析结果表明:利用简单易行的仪器来模拟工具在破碎岩石的过程中受到磨损的实质,在规定的条件下,测量标准物的磨损量,在数值上表征岩石的磨蚀性的方法是可行的;一字形钎头的磨次进尺是由岩石的磨蚀性和压入硬度共同决定的;影响岩石磨蚀性的主要因素是岩石的石英含量及粒度,岩石的压入硬度。 相似文献
19.
20.
It is a well known fact that rock mass properties influence the process of fragmentation considerably. Model blasts and field investigations were carried out to find the effects of rock mass quality and joint orientation on tunnel blasting. Propagation of shock waves are partially restricted by joint planes. It was observed that the blast results (i.e., average fragment size and depth and cross-sectional area of the broken zone) were considerably influenced by joint orientation. Accordingly, it has been concluded that loading equipment with a larger capacity and deeper blast holes are required in formations with joint planes perpendicular to the tunnel axis. The number of blast holes, however, should be greater when joints are parallel to the tunnel axis. Furthermore, the powder factor (kg/m3) has been found to be directly related to rock mass quality (Q). Optimisation of pull, powder factor and overbreak is required in the case of weak formations with joints perpendicular to the tunnel axis. The use of contour blasting technique seems to be essential in poor and fair rock masses to minimise the overbreak, reduce the support cost and improve the stability of the opening. 相似文献