Blast-induced Vibration Research Articles

Simulation of subway tunnel construction process based on fi-nite element analysis

Simulation of subway tunnel construction process based on fi-nite element analysis

Application of constitutive model in simulation analysis of tunnel construction

Application of constitutive model in simulation analysis of tunnel construction

Development of a Model to Predict Vibrations Induced by Blasting Excavation of Deep Rock Masses under High In Situ Stress

During the process of blasting excavation of deep rock masses under high in situ stress, energy produced by the explosive and the strain energy released by rock mass excavation constitute the energy source of vibration. However, in traditional Sadov’s empirical formula, the energy produced by explosive explosion is only considered which makes the error higher when it is used to predict the blasting-induced vibration peak under the condition of high in situ stress. In this study, energy transformation and distribution mechanisms caused by excavation of deep rock masses were analyzed at first. Then, a prediction model of vibration peak based on the principle of energy balance was established by dimension analysis. Finally, the proposed model was trained and tested with the vibration data monitored during the blasting excavation of deep buried tunnel in Jinping II hydropower station. The result shows that compared with the traditional prediction model, the proposed model has higher fitting correlation coefficient and lower root-mean-square error, which can be better applied to the prediction of vibration induced by blasting excavation of deep rock masses under high in situ stress.

ANFIS modelling for blast fragmentation and blast-induced vibrations considering stiffness ratio

Two independent ANFIS models were created to predict blast fragmentation and blast-induced ground vibrations. The site investigation was performed in a sandstone quarry in Istanbul Region. The first model predicts peak particle velocity. The input parameters of the ANFIS vibration model are the stiffness ratio and scaled distance. The ANFIS model was compared to classical scaled distance-based predictor equations and a multiple regression equation. Twelve predictor equations were considered to reveal actual capability of the ANFIS vibration model. The second ANFIS model predicts mean fragment size of blast muckpile. The input parameters of the ANFIS fragmentation model are the stiffness ratio and powder factor. The ANFIS fragmentation model was compared to a regression equation and the well-known Kuznetsov equation. This research specially focuses on an important but neglected design parameter, the stiffness ratio. It is believed that stiffness ratio significantly affects both ground vibration and fragmentation. The study was also aimed to perform a comprehensive and detailed model validation. Eleven error measures were used to determine prediction capabilities of the models. Performance of the error metrics was also discussed. The developed ANFIS models show quite promise. The ANFIS models have only two input parameters. Robust and noncomplex models were created.

Blast Vibration Control in A Hydropower Station for the Safety of Adjacent Structure

The transverse cofferdam in Xiangjiaba hydropower station was a water retaining concrete structure with a length of 126 m, a width of 12 m, and a height of 25.2 m, consisting of masonry, plain concrete structure (PC), and roller compacted concrete (RCC), which had to be demolished by blasting after the dam was built. There were many precise instruments nearby the cofferdam which had strict restrictions on blasting vibration. Therefore, the cofferdam was divided into six blasting regions, including land blasting and underwater blasting. Blasting parameters and blasting network structure were accurately designed and continuously optimized through blast-induced vibration test results. At nine measurement points in different locations, 57 blast vibration data were recorded. Consequently, 1386 holes with an explosive weight of 9641.3 kg were detonated in land blasting. The highest levels of vibration were recorded as 8.74 cm/s in the desilting tunnel on the right of the cofferdam. The explosives up to 11887.7 kg were detonated in an underwater blasting. According to the analysis of the law of vibration attenuation, the blast vibration value was reduced to 7.65 cm/s. The results showed that the research on the attenuation law of blasting vibration can effectively increase the charge weight per delay and control the blast-induced vibration. Consequently, the peak particle velocity (PPV) of underwater blasting could be predicted by analyzing the PPV of land blasting in same structure, which provided the basis for the design of underwater blasting parameters. A reliable method for cofferdam demolition in hydropower station was proposed, which provided a reference for similar projects.

Blast vibration dependence on total explosives weight in open-pit blasting

It is well established that the blast design parameters, namely explosives weight per delay, distance between the blast site and monitoring location, delay interval, total explosives detonated in a blasting round, velocity of detonation (VOD) of explosives, burden, spacing, explosive column length, top stemming length, number of decks and their length, transmitting media and its geology, and scattering in the delay time of detonators, influence blast-induced vibrations. A study was conducted to assess the effect of total weight of explosive detonated in the blasting round on the magnitude of blast vibrations at four big coal open-cast mines in India keeping all the parameters constant as stated above. Accordingly, experimental as well as production blasts were conducted at dragline and shovel benches. The results revealed that the magnitude of blast vibrations was influenced by the total amount of explosive detonated in a blasting round at shorter distances regardless of maximum explosives weight per delay. This paper describes the result of a study carried out to investigate these effects at open-cast projects in India. The study involved 60 blasts with varying blast designs and 498 vibration data were recorded.

Dynamic response of rock-soil dam to blasting-induced vibration with different distances

In order to assess the dynamic performance of a rock-soil damn Zhejiang, Eastern China and suggest a proper blasting scheme for the adjacent tunnel excavation, a three-dimensional finite difference model was established, and dynamic simulation analyses were carried out. Results show that close blasting will have severe impact on the stability of the dam. The different part of the dam has different response to the blasting shock. The velocity response at the side close to the blasting is far larger than that of the other side. Local damage may occur in the dam body near the blasting point. The vibration amplitude of the dam due to the blasting decreases with the distance of blasting point to the dam. The peak vibration velocity reduces to less than 0.4 cm/s and the maximum permanent displacement of the dam decreases to no more than 0.1cm when the distance between the blasting point and the dam reaches to 180m. It indicates that the blasting at this distance has little influence on the stability of the dam. So, a safe blasting distance of 180m is suggested in the project.

Attenuation assessment of blast-induced vibrations derived from an underground mine

Attenuation assessment of vibration induced by underground explosions is a source of concern due to its associated with damage analyses of underground facilities and ground structures. Based on the blast events at different levels of ore have different impacts on ground structures, to understand the attenuation rule of vertical propagation is essential for the safe design of mining blasts. In a new-built underground mine, eight seismographs were installed with different depths to monitor the blast vibrations, and 236 events included 24 events on the ground were recorded during mining production over a period of eight months. Certainly, the blasting design, propagating medium and its mechanical parameters were also carefully investigated. In the light of the collected data, various prediction equations are employed to establish a suitable relationship for describing the attenuations of peak particle velocity (PPV) and frequency. The charge weight effect on the frequency attenuation of the induced ground motion is also discussed. Moreover, the effect of surface soil overburden has also been analyzed based on a supplementary monitoring work. The results indicate that scaled distance (SD) with cube root scaling for the explosive quantity can properly perform the far-field vibration. Irrespective of how much the item of charge weight represents, its simplified form still makes the oldest equation still be widely used. The average frequency (AF) and its modified frequency equation perform well in the rock mass. The soil overburden has a low-impact on the ground motion, while the influence of charge weight per delay on ground wave frequency has diminished.

Assessment of Blast-Induced Ground Vibration at Jinduicheng Molybdenum Open Pit Mine

Ground vibration generated from blasting activities is a major problem in mine open-pit slopes and nearby properties, and it can endanger the inhabitants in the surrounding environment. To understand better the influence of blasting activities in the open-pit mine, it is important to determine the propagation and attenuation of the blast-induced vibration in open-pit slope. This paper presents a predictive model based on the Sadovsky equation for determining blast-induced ground vibration in the Jinduicheng open-pit mine, Shaanxi province, China. The field observation focused on providing measurements and data collected for the wave propagation with the influence of blasting activities. Empirical models were also used for predicting blast-induced ground vibration for comparison with the Sadovsky model. Blast design parameters such as maximum charge per delay and distance were considered as input parameters for prediction of blast-induced vibration. Site constants for different empirical equations were taken into consideration when determining the peak particle velocities in the Jinduicheng north slope. The performance indices of R2 (correlation coefficient), MSE (mean square error), RMSE (root mean square error), MAPE (mean absolute percentage error) and MEDAE (median absolute error) were calculated for the empirical models and the Sadovsky model. The results showed that the Sadovsky model is a more satisfactory model for predicting blast-induced vibration as compared to empirical models.

Predicting the blast-induced vibration velocity using a bagged support vector regression optimized with firefly algorithm

Ground vibration is the most detrimental effect induced by blasting in surface mines. This study presents an improved bagged support vector regression (BSVR) combined with the firefly algorithm (FA) to predict ground vibration. In other words, the FA was used to modify the weights of the SVR model. To verify the validity of the BSVR–FA, the back-propagation neural network (BPNN) and radial basis function network (RBFN) were also applied. The BSVR–FA, BPNN and RBFN models were constructed using a comprehensive database collected from Shur River dam region, in Iran. The proposed models were then evaluated by means of several statistical indicators such as root mean square error (RMSE) and symmetric mean absolute percentage error. Comparing the results, the BSVR–FA model was found to be the most accurate to predict ground vibration in comparison to the BPNN and RBFN models. This study indicates the successful application of the BSVR–FA model as a suitable and effective tool for the prediction of ground vibration.

CONSIDERAÇÕES SOBRE RECLAMAÇÕES RELACIONADAS ÀS VIBRAÇÕES GERADAS POR DESMONTE DE ROCHAS

In times of growing socio-environmental awareness, the ethical-moral duty to eliminate any doubts about the responsibilities of the mining industry in view of the adverse effects generated by its activity, such as the generation of ground vibrations, is a prerequisite for its sustainable continuity. Transparent and accessible communication channels to neighboring communities allows the promotion of environmental mitigation programs and information actions. However, although there is a growing evolution regarding the implementation awareness and seismographic monitoring programs, a significant portion of the complaints, coming from rock blastinduced vibrations within the legal limits, continue to exist. Therefore, the present work aims to review the main concepts involved in claims related to rock blast-induced vibrations, as well as to discuss the results from complains against a gold mine in New Zealand.

Modelling the effect of blast-induced vibrations on the stability of a faulted mine slope

SYNOPSIS Blasting, which is carried out regularly in open-pit mines, causes considerable ground vibration in the vicinity of the blasting site. These vibrations may affect the stability of mine slopes, causing problems in safety and constituting a hazard to life and property. In this study, the effect of the blasting-induced vibrations on slope stability was investigated using finite element (FE) analysis. A pit slope containing a fault was examined under seismic loading caused by successive explosions with varying intensity. Some reference points were selected above/under the fault surface and their motions recorded during the FE analysis. The results show that the points above the fault surface have the greatest displacement, while below the fault surface, only minimal (negligible) motions occur. Also, the intensity of the explosion has the greatest impact on motions at the upper points, but below the fault surface, the effect of the blast intensity was minimal. Usually, each explosion causes only small displacements in the mine slopes, but the destabilizing effect of repeated weekly blasts is significant, as confirmed in the present study. A sensitivity analysis proved a direct relationship between both the shear stiffness and friction angle of the fault surface and the motions of upper reference points. Likewise, in the presence of underground water pressure, the blasting-induced movements increase sharply. Keywords: blasting, slope stability, finite element analysis, dynamic analysis.

Response control of adjacent structures subjected to blast-induced vibrations

The response reduction efficiency of passive control viscous dampers installed between adjacent structures subjected to blast-induced vibrations was investigated. The blast-induced vibrations studied were mainly due to mining activities along with the accidental explosions in underground storage chambers. Equations of motion formulated by different researchers in examining the performance of damper-connected structures were reviewed. Two different types of structures (similar and dissimilar buildings) were selected to analyse the effectiveness of damper-connected buildings. A parametric study was also conducted to determine the optimum damper placement locations along with optimum damper properties for the similar buildings connected with viscous dampers. The results showed the efficiency of viscous dampers for the case of similar buildings. For dissimilar buildings, the peak responses were found to be almost equivalent for both connected and unconnected structures. Therefore, the root mean square responses were evaluated to compare the effect of blast vibrations beyond the initial impulse for the case of connected dissimilar buildings. In addition, the performance of similar structures connected with the same damping was compared with the responses obtained from different damping conditions to minimise the damping coefficient of dampers.

Study on blast-induced vibrations of a tunnel cross section

Construction blasting in a tunnel in deep-buried soft rock will undoubtedly influence the cross section of the tunnel. Taking the deep-buried soft rock tunnel as the research background, a field monitoring experiment of the tunnel blast-induced vibrations is carried out. The cross section was established using 5 monitoring points to collect the peak particle velocity (PPV) data and frequency spectrum data. The results show that the maximum horizontal radial component of the blast-induced vibration velocity is greater than the maximum vertical component in the deep soft rock tunnel, and the maximum vertical component is greater than the horizontal tangential component. Due to the presence of an inclined shaft, the high domain frequencies have an amplification effect on the tunnel, while low frequencies do not exhibit significant amplification effects.

An innovative technique of simplified signature hole analysis for prediction of blast-induced ground vibration of multi-hole/production blast: an empirical analysis

Prediction and control of blast-induced ground vibration is a matter of concern in mining industry since long. Several approaches ranging from scaled distance regression, different numerical methods to wave superimposition theories have been tried by many researchers for better prediction and control of blast-induced ground vibration. Signature hole analysis is one of the popular simulation methods to predict the ground vibration generated due to production blast. It superimposes the recorded signature hole waveform using a computer program to predict the production blast-induced vibration. The technique inputs the designated time of detonation of each hole and superimposes the waves generated by each hole to predict the nearest value of peak particle velocity and frequency of blast-induced ground vibration. Although a very useful approach, it requires a computer program to simulate the linear superimposition of waveforms. The simulation is not possible for every blast as it takes time and also is difficult for field engineers to simulate every time, whereas it is always easy for blasting engineers to adapt and use an empirical equation/approach for prediction and control of blast-induced ground vibration than simulation. In this paper, an attempt has been made to develop an innovative and simplified analytical approach of signature hole analysis. The simplified sinusoidal wave equation is obtained from recorded signature hole ground vibration waveform properties and is superimposed mathematically according to the multi-hole blast design to predict the production blast-induced ground vibrations. The validation of the developed approach was done in three different sites, and up to 15% more accuracy in prediction of the blast, vibrations are achieved in comparison with signature hole analysis prediction.

Ariyet Ocağında Kontrollü Patlatmalarla İlgili Bir Çalışma

Patlatma kaynaklı titreşimler çevre sakinlerini, tüm çevresel sorunlardan daha fazla endişelendirmektedir. Bina üst yapılarına verilen zararın patlatmadan kaynaklandığı iddia edilmektedir ve bazen bina sahibi, patlatma işlemlerini gerçekleştiren şirkete karşı dava açmaktadır. Patlatma kaynaklı titreşim problemi geçmişte kapsamlı bir şekilde araştırılmış ve devam eden araştırmalara konu olmaya devam etmektedir. Bu makale, bir otoyol prosesi kapsamında faaliyet gösteren taş ocağında yapılacak patlatmaların yüzeyden 9-10 m derindeki karstik kireçtaşlarına ve yeraltı sularına herhangi bir olumsuz etki etmemesi için gerekli çalışmaları içermektedir. Bu amaçla, titreşim ölçümü ve analizi yapılmış ve hedef bölgedeki patlatma kaynaklı yer titreşimlerini en aza indirgeyen yeni bir metodoloji uygulanmıştır. Patlatmanın neden olduğu zemin titreşiminin analizinde tepe partikül hızı ve baskın frekanslar dikkate alınmıştır. Metodoloji, hedef bölgedeki yüzey dalgalarının tahribatlı etkileşimini sağlamak için patlatma deliği gruplamaları arasında en uygun zaman gecikmelerini kullanmayı amaçlamaktadır.

Controlled blasting in underground construction: A case study of a tunnel plug demolition in the Neelum Jhelum hydroelectric project

Blasting is a popular method of excavation in underground construction. Blast-induced vibrations, however, if not properly controlled, can negatively affect the rock mass surrounding the tunnel. During the drill-and-blast (D&B) excavation of twin headrace tunnels through a major fault zone below the Jhelum River, a 180-m3/h groundwater inflow occurred from the tunnel invert. A 610-m3 concrete plug and high-pressure grouting around the tunnel periphery were formed to stabilize the tunnel and control inflow. To complete the tunnel, the temporary tunnel plug was ultimately demolished using controlled blasting. Ground vibration monitoring data from the regular D&B operations were used to develop a site-specific vibration attenuation model. Using geotechnical data from the feasibility stage and tunnel mappings during construction, a critical particle velocity above which tensile cracking could be initiated was determined for the rock mass surrounding the plug. The critical particle velocity was incorporated into the vibration attenuation model to obtain permissible charge weights to limit blast damage to within a short distance from the charge. Using this approach, an innovative blasting pattern was adopted in which the tunnel plug was sequentially demolished by detonating a burn cut and separate contour blast rows. During blasting, rigorous supervision and data collection helped to record, evaluate, and when needed, adjust the blasting program. Overall, the tunnel plug demolition was completed in a safe and cost-effective manner.

Prediction of frequency-dependent attenuation of blast-induced vibration in underground excavation

Frequency-based criteria for control of blasting vibrations require methods to predict both peak particle velocity and dominant frequency. In this study, based on the theory of dynamics of structures a mechanical model is built firstly to derive vibration response to a cylindrical explosion source. According to model analysis, a theoretical formula is proposed to predict the frequency-dependent attenuation of vibration induced by cylindrical explosion source. With the application of dimensional analysis, a mathematical relationship is established between the dominant frequency and its principal influencing factors. The prediction formulae derived from model analysis, and dimensional analysis showed completely consistency in the formula form, indicated that the formula obeys both the method of dynamics of structures and the dimensional homogeneity. In the end the applicability of the proposed formula is verified by single-hole blasting experiments. The prediction accuracy of the proposed formula is compared with some other prediction formulae and the new proposed formula proved to be superior with a higher fitting degree and lower deviation. In addition, application of the prediction method in multi-hole blasting is discussed. With a simplified equation to predict dominant vibration frequency, the research would give a significant guiding path for future blasting engineering.

Comparative Study of Tunnel Blast-Induced Vibration on Tunnel Surfaces and Inside Surrounding Rock

In tunnel blast applications, vibration monitors are typically placed on tunnel surfaces to measure the responses of rock to explosion loads for statutory compliance. Few publications in the open literature have focused on the differences between the blasting vibration on tunnel surfaces and inside the surrounding rock. During blasting excavation of the experimental tunnels in the China Jinping Underground Laboratory, velocity sensors were arranged both on the tunnel walls and inside the surrounding rock to monitor far-field vibrations. In this paper, the vibration characteristics on the tunnel surfaces and inside the surrounding rock are presented based on the recorded field data. Corresponding empirical formulae for peak particle velocity (PPV) attenuation and dominant frequency variation are derived from these data. A three-dimensional dynamic finite-element model is used to verify the site survey results. The field and numerical studies show that compared with the inside vibration, the tunnel surface vibration has a higher, more readily attenuated PPV and a lower frequency with a slower rate of decline in the dominant frequency. The mechanisms that cause the differences between the surface and inside vibration are discussed in detail. The tunnel surface vibration in the far field is dominated by surface waves, which occupy more than 75% of the total vibrational energy. For this reason, the results presented in this paper do not apply to vibration in the near field, where body waves are expected to be dominant.

Analysis of predictor equations for determining the blast-induced vibration in rock blasting

The paper proposes a new empirical correlation designed to complement the “site laws” currently used to evaluate the attenuation in the rock masses of vibrations induced by rock blasting. The formula contains a deformed exponential known as the K-exponential, which seems to well represent a large number of both natural and artificial phenomena ranging from astrophysics to quantum mechanics, with some extension in the field of economics and finance. Experimental validation of the formula was performed via the analysis of vibration data covering a number of case studies, which differed in terms of both operation and rock type. A total of 12 experimental cases were analysed and the proposed formulation exhibited a good performance in 11 of them. In particular, the proposed law, which was built using blast test data, produced very good approximations of the points representing the vibration measurements and would thus be useful in organising production blasts. However, the developed formula was found to work less well when a correlation obtained for a given site was applied to another presenting similar types of rocks and operations, and thus should not be employed in the absence of measurements from test data.