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1.
Drilling and blasting is a major technology in mining since it is necessary for the initial breakage of rock masses in mining. Only a fraction of the explosive energy is efficiently consumed in the actual breakage and displacement of the rock mass, and the rest of the energy is spent in undesirable effects, such as ground vibrations. The prediction of induced ground vibrations across a fractured rock mass is of great concern to rock engineers in assessing the stability of rock slopes in open pit mines. The waveform superposition method was used in the Gol-E-Gohar iron mine to simulate the production blast seismograms based upon the single-hole shot vibration measurements carried out at a distance of 39 m from the blast. The simulated production blast seismograms were then used as input to predict particle velocity time histories of blast vibrations in the mine wall using the universal distinct element code (UDEC). Simulated time histories of particle velocity showed a good agreement with the measured production blast time histories. Displacements and peak particle velocities were determined at various points of the engineered slope. The maximum displacement at the crest of the nearest bench in the X and Y directions was 26 mm, which is acceptable in regard to open pit slope stability.  相似文献   

2.
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   

3.
The purpose of this article is to evaluate and predict the blast induced ground vibration using different conventional vibration predictors and artificial neural network (ANN) at a surface coal mine of India. Ground Vibration is a seismic wave that spread out from the blast hole when detonated in a confined manner. 128 blast vibrations were recorded and monitored in and around the surface coal mine at different strategic and vulnerable locations. Among these, 103 blast vibrations data sets were used for the training of the ANN network as well as to determine site constants of various conventional vibration predictors, whereas rest 25 blast vibration data sets were used for the validation and comparison by ANN and empirical formulas. Two types of ANN model based on two parameters (maximum charge per delay and distance between blast face to monitoring point) and multiple parameters (burden, spacing, charge length, maximum charge per delay and distance between blast face to monitoring point) were used in the present study to predict the peak particle velocity. Finally, it is found that the ANN model based on multiple input parameters have better prediction capability over two input parameters ANN model and conventional vibration predictors.  相似文献   

4.
Excavation of coal, overburden, and mineral deposits by blasting is dominant over the globe to date, although there are certain undesirable effects of blasting which need to be controlled. Blast-induced vibration is one of the major concerns for blast designers as it may lead to structural damage. The empirical method for prediction of blast-induced vibration has been adopted by many researchers in the form of predictor equations. Predictor equations are site specific and indirectly related to physicomechanical and geological properties of rock mass as blast-induced ground vibration is a function of various controllable and uncontrollable parameters. Rock parameters for blasting face and propagation media for blast vibration waves are uncontrollable parameters, whereas blast design parameters like hole diameter, hole depth, column length of explosive charge, total number of blast holes, burden, spacing, explosive charge per delay, total explosive charge in a blasting round, and initiation system are controllable parameters. Optimization of blast design parameters is based on site condition and availability of equipment. Most of the smaller mines have predesigned blasting parameters except explosive charge per delay, total explosive charge, and distance of blast face from surface structures. However, larger opencast mines have variations in blast design parameters for different benches based on strata condition: Multivariate predictor equation is necessary in such case. This paper deals with a case study to establish multivariate predictor equation for Moher and Moher Amlohri Extension opencast mine of India. The multivariate statistical regression approach to establish linear and logarithmic scale relation between variables to predict peak particle velocity (PPV) has been used for this purpose. Blast design has been proposed based on established multivariate regression equation to optimize blast design parameters keeping PPV within legislative limits.  相似文献   

5.
It is becoming increasingly important, from an environmental viewpoint, to minimize vibrations induced in urban dwellings by blasting. The present study illustrates how the delay interval between blastholes can be chosen to control and minimize the vibration energy within the structural response band of most houses. In particular, it is shown that the only possibility of reducing such energy is to employ a delay interval in the range 10–35 ms. However, the induced vibrations are also dependent upon the accuracy of the delay initiators as well as the level of random fluctuations between each blasthole signature. It is shown that only very accurate electronic delays give the possibility of utilizing fully the delay sequence in order to control structural vibrations. If the vibration emission from each blasthole is totally uncorrelated with that of any other blasthole then the resulting amplitude spectrum of the blast will be totally unpredictable. This situation occurs irrespective of the delay initiation sequence or its accuracy. Under these conditions it is impossible to predict the blast-induced energy lying within the structural response band.  相似文献   

6.
In order to control or reduce the ground vibrations caused by underground blasts in Malmberget mine, a number of blast tests were carried out during production blasts and a series of single shot waveforms were obtained. Then the single shot waveforms from the same ring or different rings were analysed and compared with each other. The results showed that the single shots are reproducible, meaning that the ground vibrations caused by underground blasts can be controlled by means of the interference of the vibration waveforms measured. Finally, a formal test using electronic detonators and employing an optimum delay time of 8 ms was done in production. The test for an 11-borehole ring shows that the maximum vertical ground vibrations are reduced to the maximum vertical vibrations of a single shot. Particularly, the total vibration history for the 11-borehole-ring blast is shortened to about 200 ms over a velocity of 2 mm/s. However, the total vibration history of a normal production blast of 11-borehole ring is always 1400 ms over a velocity of 2 mm/s, namely the total vibration time of a production blast can be reduced to one seventh of that of the common production blasts by using the vibration control method. This indicates that the vibration control method introduced in the paper is feasible for underground mining blasts.  相似文献   

7.
单临空面岩体中爆破诱发损伤的数值分析   总被引：1，自引：1，他引：0  
岩石的抗压强度远大于其抗拉强度,所以在单临空面岩体爆破中,工程技术人员关注的不仅是炮孔附近的塑性压剪损伤,更多的是临空面附近的拉裂损伤,临空面若是地表,可能会影响到施工的安全,甚至造成一定的经济损失。以往这类损伤问题的数值模拟中大多只偏向于一方面：或忽略压剪损伤,或不考虑拉裂损伤,故所得出的结论难以满足工程需要。基于合理的应力修正方式,把现有的岩石拉-压损伤本构以简明的方式嵌入到大型LS-DYNA软件中,对单临空面岩体中的柱形和球形药包爆破问题进行了数值模拟,计算结果表明该法能较好地预测岩体中爆破诱发的拉裂、压缩损伤的分布规律和演化趋势。  相似文献   

8.
This research was performed on the quarry that will be opened to produce aggregates and rock filling material at Catalagzi region at Zonguldak province in Turkey. However, there are some structures which can be adversely affected by blasting at the quarry. These structures are a methane exploration drill hole and a house at the distances of 340 and 390 m, respectively. One of the main goals of this study is to perform a preliminary assessment of possible damage effect of ground vibrations induced by blasting on these structures by risk analysis based on ground vibration measurements. In order to propose a preliminary blast design models separately for aggregate and rock filling material production, six test shots with different maximum charge per delay were planned and fired at the quarry. In these shots, 90 events were recorded. To predict peak particle velocity (PPV), the relationship between the recorded peak particle velocities and scaled distances were investigated. During this investigation, the data pairs were statistically analyzed and a PPV prediction equation specific to this site with 95% prediction line were obtained. And also, this equation was used in the derivation of the practical blasting charts specific to this site as a practical way of predicting the peak particle velocity and maximum charge per delay for future blasting. A risk analysis was performed by using this equation. In the light of this analysis, preliminary blast design models were proposed to be used in this quarry for aggregate and rock filling material production.  相似文献   

9.
Blasting constitutes a beneficial industrial technology, used in quarries and mining production processes, which ensures the achievement of the expected results in a short period of time with relatively low cost. Nevertheless, a significant part of the used blasting energy is wasted in the form of ground vibration and air blast. Hence, blasting-induced ground vibrations are one of the fundamental problems in the mining industry which may cause severe damage to structures and plants nearby. Therefore, a vibration control study plays an important part in the minimization of the environmental effects of blasting in mines. This study represents an investigation reporting ground motion (measured in terms of peak particle velocity (mm/s)) and air blast overpressure measurements around the open-pit phosphate mine near Metlaoui area (southwestern Tunisia). It aimed to calculate the site’s constants: K (ground transmission coefficient) and n (site attenuation curve slope). The obtained site parameters allowed determining the propagation equation of the blast-induced seismic waves in the study area. The scope of this study was to predict the peak particle velocity when the amount of explosive charge and/or the distance were altered with minimum spoil to the environment. Also, a frequency overview of the study area revealed the dominance of low frequencies (>?40 Hz). Such values can cause damage to the nearby structures when a specific peak particle velocity value is reached by blasting. Moreover, this study demonstrated that all overpressure magnitudes were less than 134 dB, which is the safe limit of air blast level.  相似文献   

10.
There is a common belief within the blasting community that increasing the burden will increase the blast vibration. In order to test this belief in a direct sense, it would be desirable to fire single blastholes with various burdens and monitor the vibrations at many locations. A review of past literature indicates that such direct tests are rare and only scant data is available. Nevertheless, a detailed analysis of this and associated past work (on small-scale blocks and choke blasts) shows no convincing evidence of an influence of burden on blast vibration. On the other hand, by considering the role of reflected waves in a simple analytical model, reasoning is given to show that the vibration might well be insensitive to burden. In view of the scant data available, it was decided to conduct trials of a direct nature, in which 13 single blastholes were fired to a free face. The burdens chosen were 2.6 m, 5.2 m and 10.4 m, and the vibration was measured at typically 10 locations over the range 5 m to 50 m from each hole. The results clearly show that the vibration is independent of such burdens. Furthermore, a side-by-side comparison of a choke blast with a free-face blast showed that the vibration from the holes in the choke blast was not higher than the vibration from the holes in the free-face blast. The present work also shows that vibration, although insensitive to burden, is not insensitive to the condition (i.e., the degree of damage) of the surrounding rock mass. In this regard, blastholes in undamaged ground produce a significantly higher vibration than blastholes in damaged ground. This might well be the reason why pre splits and drop-cuts are observed to produce relatively high vibrations, i.e., it is not because such blasts typically involve large burdens, but rather that they are usually initiated in relatively undamaged ground.  相似文献   

11.
The vibrations of existing service tunnels induced by blast-excavation of adjacent tunnels have attracted much attention from both academics and engineers during recent decades in China. The blasting vibration velocity (BVV) is the most widely used controlling index for in situ monitoring and safety assessment of existing lining structures. Although numerous in situ tests and simulations had been carried out to investigate blast-induced vibrations of existing tunnels due to excavation of new tunnels (mostly by bench excavation method), research on the overall dynamical response of existing service tunnels in terms of not only BVV but also stress/strain seemed limited for new tunnels excavated by the full-section blasting method. In this paper, the impacts of blast-induced vibrations from a new tunnel on an existing railway tunnel in Xinjiang, China were comprehensively investigated by using laboratory tests, in situ monitoring and numerical simulations. The measured data from laboratory tests and in situ monitoring were used to determine the parameters needed for numerical simulations, and were compared with the calculated results. Based on the results from in situ monitoring and numerical simulations, which were consistent with each other, the original blasting design and corresponding parameters were adjusted to reduce the maximum BVV, which proved to be effective and safe. The effect of both the static stress before blasting vibrations and the dynamic stress induced by blasting on the total stresses in the existing tunnel lining is also discussed. The methods and related results presented could be applied in projects with similar ground and distance between old and new tunnels if the new tunnel is to be excavated by the full-section blasting method.  相似文献   

12.
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   

13.
A new site-specific vibration prediction equation was developed based on site measurement performed in a sandstone quarry. Also, several vibration prediction equations were compiled from the blasting literature and used to predict ground vibration for the studied quarry. By this way, site-specific equation created by regression analysis and the equations obtained from the blasting literature were compared in terms of prediction accuracy. Some of the equations obtained from the literature made better predictions than the site-specific equation created for the studied quarry. The prediction equations were grouped, and the effects of the rock formation and mine type on the prediction accuracy were investigated. Suitable error measures for evaluation of ground vibration prediction were examined in detail. A new general prediction equation was created using site factors (K, β) of the examined studies. The general equation was created using 17 prediction equations reported by blast researchers. Prediction capability of the general equation was found to be strong. Diversity of the blast data is one of the strongest features of the general equation.  相似文献   

14.
An intelligent approach to prediction and control ground vibration in mines   总被引：8，自引：0，他引：8  
Drilling and Blasting are still considered to be the most economical method for rock excavation either on surface or underground. The explosive energy, which breaks the rockmass, is not fully utilized for this purpose. Only 20–30% of explosive energy is utilized for fragmenting the rockmass and the rest wasted away in the form of ground vibration, air blast, noise, fly rock, back breaks, etc. Among them, ground vibration is considered to have the most damaging effect. A number of predictor equations have been proposed by various researchers to predict ground vibration prior to blasting. Still, it is difficult to recommend any one predictor for a particular ground condition because ground vibration is influenced by a number of parameters. These parameters are either controllable or non-controllable like blast geometry, explosive types, rock strength properties, joints patterns, etc. In the present paper, an attempt has been made to predict the ground vibration using an Artificial Neural Network incorporating large number of parameters, which affect the ground vibration. Results are also compared with the values obtained from regression analysis and observed field data sets. Finally, it is found that the neural network approach is more accurate and able to predict the value of blast vibration without increasing error with increasing number of inputs and non-linearity among these.  相似文献   

15.
Rock mass failure is a particularly complex process that involves the opening and sliding of existing discontinuities and the fracturing of the intact rock. This paper adopts an advanced discretisation approach to simulate rock failure problems within the discontinuous deformation analysis (DDA) framework. The accuracy of this approach in continuum analysis is verified first. Then, the advanced discretisation approach for fracturing modelling is presented, and the discretisation strategy is discussed. Sample rock static failures are simulated and the results are compared with experimental results. Thereafter, with a generalised definition of the artificial joints, this approach is further extended and applied in the simulation of blast-induced rock mass failures in which the instant explosion gas pressure obtained by the detonation pressure equation of state is loaded on the main blast chamber walls and the induced surrounding connected fracture surfaces. In the simulation instance of rock mass cast blasting, the whole process, including the blast chamber expansion, explosion gas penetration, rock mass failure and cast, and the formation of the final blasting pile, is wholly reproduced.  相似文献   

16.
A number of factors influence the generation, propagation and intensity of ground vibrations. However, there are conflicting opinions with regard to the influence of the blast size on the intensity of ground vibrations. This paper discusses the experiments conducted in an opencast coal mine in India and a simulation study carried out to establish the influence of total charge in a blast on the intensity of ground vibrations. Studies clearly indicate that the total explosive charge in a blast has insignificant influence on the intensity of ground vibrations for distances between 100 m and 3000 m.  相似文献   

17.
This paper presents the influence of various discontinuities, natural or artificial, on magnitude and frequencies of blast induced ground vibrations. These discontinuities were geological faults, a pond, a shaft incline, a trench and a pre-split plane interposed in the path of vibration propagation. In the post-trench region, ground vibrations in terms of peak particle velocity were significantly reduced and dominant frequencies in higher bands were consequently observed. Depth of trench with respect to blastholes were varied and consequent vibration characteristics were analyzed. The techniques of creating a trench and pre-split plane were successfully implemented in controlling vibration and in increasing the explosives charge to meet the scheduled production target of an opencast mine. Comparisons of ground vibration characteristics affected by a trench and a pre-split plane of the same depth are described in the text. The findings lead to the conclusion that such experimental data are necessary for production blasting in open cast mines under constrained conditions.  相似文献   

18.
In bench blast design, not only the technical and economical aspects, such as block size, uniformity and cost, but also the elimination of environmental problems resulting from ground vibration and air blast should be taken into consideration. Prediction of ground vibration components is of great importance when responding to and avoiding environmentally-related complaints. This paper presents the results of ground vibration measurements carried out in a celestite open-pit mine during blast optimisation studies. The particle velocity components (longitudinal, transversal, vertical and peak) and the airblast measurement results were evaluated considering the scaled distance relationship. The statistical analysis of 47 data sets yielded an empirical relationship between peak particle velocity and scaled distance. This approach which is suggested for the present site gives the 50% line and the upper bound 95% prediction limit with reasonable correlation.  相似文献   

19.
Due to the large-scale sub-level caving in Malmberget mine and the short distance between the mine and Malmberget town, the ground vibrations in the town have reached a high level since the year 2001 when large scale caving mining started. In order to control and reduce the high vibrations, LKAB launched a research project on active reduction of vibrations in Malmberget by using the wave interference or wave superposition method with electronic detonators. By means of this method, the vertical vibrations were reduced by 10% and the total vibration time for a ring blast was reduced by 80% according to five ring tests in the mine. For a further reduction of the vibrations, a second method, named changing initiation sequence in ring blasts, was developed on the basis of stress wave theory and the geographic conditions of the town and the mine. The second method has so far been applied in all of the drifts near the town, and the vibrations measured at the town show that the vertical vibrations caused by production blasts in the mine have been reduced by more than 31% on average. In addition, a third method, dividing a ring into two parts during blasting, was developed and used to reduce the ground vibrations from a number of very large rings in the mine. The results indicate that the vibrations have been reduced by more than 33%, and a more interesting and surprising result is that ore extraction has been increased by the third method.  相似文献   

20.
Vibrations due to production blasting can induce damage to the rock mass at large distances by altering larger geological structures, fault areas or other structures, where the orientation with respect to the mine geometry is unfavorable and can cause displacement of large rock volumes. Past occurrences of this nature in Escondida Mine placed geomechanical safety restrictions as to maximum allowable blast size in the northeast area of the mine. These restrictions limited the efficiency of drilling and blasting operations seriously limiting daily production. This is what prompted this study to attempt to increase shot size while reducing stability problems. This would permit keeping stable the slope over which the ore extraction belts are located, as well as the main access ramp to the mine. Using a rigorous and systematic instrumentation and monitoring effort of blasting vibrations at multiple locations with respect to an unstable location allowed the development of a database to establish acceptable vibrations limits. A parallel effort was the development and gauging of a mechanistic model for the prediction and simulation of blasting vibrations. Excellent results were obtained from a comparison between the measured and predicted results. This allowed the use of the gauged model to verify the practicality of increasing the shot size in the restricted blasting zones, without exceeding safe vibration limits. The practical success achieved using this research approach resulted in increased blasting size, with a consequent increase of blasted material per shot, and contributed to more flexible mining operations.  相似文献   

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