Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
33 results
Search Results
Item Assessment of objective based blast performance: Ranking system(CRC Press, 2012) Sastry, V.R.; Ram Chandar, K.R.Rock fragmentation using chemical energy is commonly followed for fragmenting and displacing the rock mass in mining, civil and other excavation projects. In case of mines, the objective of rock fragmentation is to get a uniform sized material to suit the subsequent operations like loading, hauling and crushing. In case of civil engineering projects like canals, tunnels, it is to provide the space for some facilities and the material produced may not be having a specific use. In case of blasting near to the human habitats or important structures like dams, ground vibrations generated should be within permissible safe limits, along with proper fragmentation. Cost reduction is also a prime factor in all the cases. In general, assessment of blast performance refers to fragmentation assessment. However, based on the objective, the approach to blast design may be different. An attempt is made through this paper to discuss different blast performance assessment methods, through a case study and a ranking system is proposed. Field studies were carried out in a limestone mine in southern India, using eight controlled blasts by changing the initiation system, initiation pattern and maintaining same blast geometry parameters. Blast performance was assessed based on fragmentation using digital image processing technique, energy distribution, and productive yield and powder factors resulting from the blasts. Rankings were given to different blasts as per the performance. © 2013 Taylor & Francis Group, London. © 2013 by Taylor & Francis Group, LLC. All rights reserved.Item Elimination of ground vibrations and fly rock: A case study of an opencast mine(2001) Sastry, V.R.At the JK Opencast Project, studies were made to eliminate the problems of ground vibrations and fly rock. Ground vibrations were studied with blast vibration monitors. Changes in the initiation pattern from earlier V-pattern to the straight-line pattern and reduction in charge weight per delay, resulted in elimination of ground vibrations problem. Adoption of straightrow pattern of initiation with a clear free face, introduction of air deck, bottom initiation of blastholes and muffling of individual holes with wire meshes overlain by sand bags of 25 kg resulted in complete elimination of fly rock.Item Minimizing power consumption in multiple fan networks by optimum fan selection(Soc for Mining, Metallurgy & Exploration Inc, 1995) Kumar, G.Vijaya; Sastry, V.R.; Krishna Rao, G.V.One of the main objectives while planning ventilation systems for mines with multiple fans is minimization of the total airpower consumption of the mine. Solution of this problem by conventional ventilation network analysis programs is tedious and time consuming, and may not yield optimum results in all the cases. The paper presents an algorithm for solving multiple fan networks by finding optimum combination of fan operating points for required airflow distribution in the ventilation system.Item Under Water Blasting for Rock Dredging in Ports: Case Study of A Major Port(2003) Sastry, V.R.A blast design for carrying out under water blasting for rock dredging, in ports for expansion, is discussed. The project adopted had three-phase methodology, which includes, pre-blast monitoring and planning, in-blast monitoring and post-blast analysis. The process involved acquiring borehole data of the area for assessing the geological condition of the rocks and gaining information about physico-mechanical properties. Structures in the port were surveyed to assess their condition for safe execution of the blasts. The proposed method helped in achieving optimum fragmentation and in protecting structure from the blast vibrations.Item Effect of lower seam old workings on longwall powered supports in upper seam(2007) Sastry, V.R.; Nair, R.; Venkat Ramaiah, M.S.Load bearing capacity of powered roof supports is a key issue in the design of longwall panels. The existence of multiple seams in a given project may involve over mining or undermining operations across different seams. The paper envisages variation in stress distribution and load on powered supports in the upper seam longwall panel due to the presence of already mined out bottom seam consisting goaf, pillars and openings through detailed field investigations in an underground coal mine followed by finite element modeling study. Studies revealed that for every 40 m of face retreat, the load from the roof gradually gets transferred from the panel to the goaf. Stress distribution over chock shields was considerably affected when the face in upper seam reached 15-25m zone above the openings in lower seam. The presence of barrier in the bottom seam increases load on the chock shields in longwall panel of upper seam. © 2007 Taylor & Francis Group, London.Item Assessment of blast performance based on energy distribution(2008) Sastry, V.R.; Ram Chandar, K.Effective utilization of explosive energy in and around the blasthole gives better fragmentation with reduced unwanted results. Ineffective utilization of energy leads to dissipation of energy in the form of ground vibrations, noise, fly rock, back break etc. An attempt is made in this paper to present the results of the study on blast performance based on the energy dissipated into ground vibrations by analyzing the wave forms and estimating the energy distribution around blastholes by simulating blast patterns using JkSimBlast software.Generally, ground vibrations generated due to blasting operations are monitored at a known distance from blast site with a geophone / ground vibration monitor, in three mutually orthogonal, i.e longitudinal, transverse and vertical directions. Using such wave forms, the work done (energy) was estimated for all the signals in three directions, based on the principle that the area within the curve is 'work done'. Summation of energy in all three directions was considered to estimate the total work done (energy) from each blast event. Fourteen blasts were conducted in a limestone mine in southern India in 7 pairs. In each pair, one blast was conducted with shocktube initiation and other one with detonating cord initiation, keeping initiation patterns and all other parameters constant. Ground vibrations monitoring distance was also kept constant in each pair of blasts. The events were analyzed and the work done was estimated for each event. It was found that the detonating cord initiated blasts dissipated higher energy in the form of ground vibrations compared to shocktube initiated blasts. The blast performance was assessed based on the energy distribution around the blastholes. A comparative analysis was done with both the initiation systems. Once the blasthole is initiated, the explosive energy dissipates into the rock mass in the form of strain waves. The energy will be high at the vicinity of the blastholes, and it dissipates gradually with distance. If the energy is higher than the breaking strength of the rock mass the rock mass gets fragmented. Based on this concept, the blast patterns were simulated using JkSimBlast software. Around the blastholes, the energy distribution was divided into four zones / ranges. It was found that the area of highest energy zone around the blastholes is larger for shock tube initiated blasts than the detonating cord initiated blasts, which indicates effective energy utilization with shocktube initiation system.Item Assessment of objective based blast performance: Ranking system(2013) Sastry, V.R.; Ram Chandar, K.R.Rock fragmentation using chemical energy is commonly followed for fragmenting and displacing the rock mass in mining, civil and other excavation projects. In case of mines, the objective of rock fragmentation is to get a uniform sized material to suit the subsequent operations like loading, hauling and crushing. In case of civil engineering projects like canals, tunnels, it is to provide the space for some facilities and the material produced may not be having a specific use. In case of blasting near to the human habitats or important structures like dams, ground vibrations generated should be within permissible safe limits, along with proper fragmentation. Cost reduction is also a prime factor in all the cases. In general, assessment of blast performance refers to fragmentation assessment. However, based on the objective, the approach to blast design may be different. An attempt is made through this paper to discuss different blast performance assessment methods, through a case study and a ranking system is proposed. Field studies were carried out in a limestone mine in southern India, using eight controlled blasts by changing the initiation system, initiation pattern and maintaining same blast geometry parameters. Blast performance was assessed based on fragmentation using digital image processing technique, energy distribution, and productive yield and powder factors resulting from the blasts. Rankings were given to different blasts as per the performance.Item Investigation on dust generated during rock cutting by ansys software(TMMOB Maden Muhendisleri Odasi, 2015) Raghavan, V.; Murthy, C.S.N.; Sastry, V.R.Underground coal mining operations continue to increase production as mining equipment and practices are improved. Unfortunately, increased production also results in the potential for increased Respirable dust generation and worker exposure. In response, operations are applying basic controls at elevated levels and looking to emerging technologies in an effort to better control Respirable dust levels. Ventilating air and water sprays remain the basis of dust control strategies for both longwall and continuous mining operations, and the level of application for these controls continued to increase. In addition, new technologies are emerging that have the potential to further reduce dust levels. In this Paper an attempt is made to study the Stresses Produced and its Influence on Dust generation at different Attack angle and force applied on the cutting material.Item Signal processing computation based seismic energy estimation of blast induced ground vibration waves(Institute of Electrical and Electronics Engineers Inc., 2016) Sastry, V.R.; Garimella, G.R.Study of ground vibrations resulted from blasting operations in mines and quarries is significant ecological aspect. In general, very lesser amount of explosive energy will be utilized in blasting process for breakage and creation of fragmentation, however the remaining will be squandered in the form of shock waves. Shock waves resulted from blasting operations cannot be entirely abolished, nonetheless can be lessened to the extent possible using an appropriate blasting methodology. Substantial work has been performed to detect ground vibrations for assessing the blast performance using the intensity of ground vibrations. Nevertheless, not much research has carried in the estimation of seismic energy and utilizing this energy for assessing the performance of blast rounds. In this paper, a Signal Processing based technique for the estimation of seismic energy dissipated at various distances is proposed. In total, 116 blast vibration events from Limestone Mines, 96 blast vibration events from Underground Coal Mine and 43 blast vibration events from Sandstone Mines were collected and respective signal processing analysis was carried out using Advanced Blastware and DADiSP software. Each vibration event in one direction carries about 2500 particle motion samples. © 2016 IEEE.Item Blast vibration signal analysis using S-transform(Institute of Electrical and Electronics Engineers Inc., 2016) Teja, V.V.S.A.; Chaitanya, S.V.; Akula, U.; Srihari, P.; Sastry, V.R.Rock blasting in mines and quarries is an important operation meant for fragmenting and displacing the hard rock mass / strata. The unavoidable environmental effect is the ground vibration, resulting from the wastage of explosive energy. Ground vibrations travelling to far off distances may have effect on the structures. Signal processing techniques play a vital role in analyzing the velocity of ground vibration signals in rock blasting. So far, time-frequency domain is being used for analyzing the ground vibration signals. However, usage of S-Transform, we get frequency dependent resolution of time-frequency domain. It is possible to simultaneously analyze the signal using time, frequency and amplitude values obtained by applying S-transform. A case study is presented in this paper, wherein the S-Transform is applied to the ground vibration velocity signals, which helps in better understanding and analysis of the signal compared to Fourier transform and Wavelet transform techniques. © 2016 IEEE.