Faculty Publications
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Item Explosive energy is the most commonly used form of energy to fragment rock mass/overburden and mineral deposits in the mines. Fragmentation obtained in the blasting process influences the downstream costs like loading cost, transportation cost, processing cost, etc. Among the various factors which influence the rock fragmentation, initiation system is one of the most important because presently much research is going on in this area of rock blasting. Some field studies were taken up with conventional detonating cord initiation and shock-tube-based NONEL initiation systems to study the influence of initiation systems on rock fragmentation. Fragmentation analysis was done using the boulder count method and image analysis. It was found that the shock-tube initiation gives 33% less boulders and 31% lesser K50 value compared to detonating cord initiation. © 2004 Taylor & Francis Ltd.(Taylor and Francis Ltd., Shock tube initiation for better fragmentation: A case study) Sastry, V.R.; Ram Chandar, K.2004Item Induced stresses in blasting gallery panel during depillaring based on field instrumentation(CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2012) Kumar Reddy, S.; Sastry, V.R.Selection of a suitable mining method for economical and safe underground extraction of a thick coal seam is an extremely delicate process and brings a number of geo-technical parameters into consideration. In fact, single lift working of full thickness of a thick coal seam has always a verge over the multi slice working due to favorable economics and high production and productivity. Charbonnage de France (CdF) proposed Blasting Gallery (BG) for extraction of virgin thick seams as well as developed pillars in thick seams in single lift. The method was very successful resulting in 85% of extraction with high productivity. But, this method experienced strata control problems during final extraction. Due to strata problems, the method was not successful at East Katras Colliery where overriding of the pillars occurred in one panel. Two BG panels (BG 2/2 and BG 1/10 panels) at GDK No. 8 Incline, Singareni Collieries Company Ltd. (SCCL) were also closed prematurely due to strata problems. In this paper, strata monitoring data of stress cells in pillars of a blasting gallery panel is analyzed for the induced stresses in a Blasting Gallery panel during depillaring in specific geo-mining and working conditions of a underground mine in Southern part of India. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Generation and accuracy assessment of digital elevation model using digital photogrammetry and differential global positioning system techniques(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Sastry, V.R.; Venkat Reddy, D.; Garimella, G.; Adithya, N.; Saiprasad, S.A.Blasting can be considered as the most crucial process in an opencast mine. It is therefore important for mining engineers to understand the effect of geological discontinuities and blast design parameters on the results of blasting. Bench height and burden are very important parameters affecting stiffness of bench. Joints alter the results of blasting, by making explosive energy utilization ineffective. Modern tools like high speed videography reveal many aspects of fragmentation process, which otherwise are difficult to visualize and understand. An attempt is made through this paper to present some of the research results of model scale studies, coupled with field study results related to bench height and joints in order to improve blast results. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Response of Strata and Buildings to Blast Induced Vibrations in the Presence and Absence of a Tunnel(Springer International Publishing, 2016) Rebello, N.E.; Shivashankar, R.; Sastry, V.R.Blast induced vibrations form an inevitable and major part of modern day construction. The changes that happen to the strata or buildings surrounding the blast are evident in a fraction of a second. Effect of damage is more pronounced in the absence/presence of the tunnel. The vibration produced due to blast may be induced due to a deep underground explosion, a surface explosion or even an in-tunnel explosion. In this study the above three situations are numerically modeled by a Distinct Element software 3DEC (3.0). Soil properties are varied representing soft and stiff strata. Further, three velocity time histories of 2, 45 and 85 Hz are used as an input in the model and are applied at three different boundaries of the model. Results of the analysis reveal that the response of building in softer strata and lower frequencies led to greater magnification of velocities and displacements compared to response of buildings in stiff strata. Presence of the tunnel led to reduction of peak velocity (PV’s) and displacements at the building top due to damping effect. PV’s at the top floor were greater than the PV’s at the bottom floor and there was an upliftment of the soil mass at the ground level. However, the upliftment in the presence of the building was lower than the upliftment in the absence of the building. Stress in the tunnel lining increased in the presence of the building, however percentage reduction of stress depends on the number of building stories. © 2016, Springer International Publishing Switzerland.Item A Critical Comparison of Regression Models and Artificial Neural Networks to Predict Ground Vibrations(Springer International Publishing, 2017) Ram Chandar, K.; Sastry, V.R.; Hegde, C.Blasting is important and an essential prerequisite in any opencast mine for fragmenting hard deposits. Blasting always produces unwanted effects like ground vibrations, noise and fly rock; among which ground vibrations effect is more on surrounding structures. Propagation of ground vibrations can lead to destruction of surrounding structures. Prediction of ground vibrations especially in terms of peak particle velocity is beneficial as opposed to conventional data monitoring techniques which can be expensive as well as time consuming. This paper uses predictors to estimate the intensity of ground vibrations and compares different methods of prediction methods like linear regression, multiple linear regression, non linear regression (NLR) and artificial neural networks. Intensity of ground vibrations generated from blasting operations was monitored in three different mines of limestone, dolomite and coal; obtaining about 168 ground vibration recordings in total. The statistical modelling or data-driven modeling has shown promise in the prediction of blast vibrations. Proposed a system of introducing site specific rock parameters like poison’s ratio, uniaxial compressive strength of rock and Young’s modulus to improve the correlation coefficient using statistical modelling (commonly called feature engineering in machine learning circles). © 2016, Springer International Publishing Switzerland.