Faculty Publications

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    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.
    2004
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    An experimental investigation of jack hammer drill noise with special emphasis on drilling in rocks of different compressive strengths
    (2007) Vardhan, H.; Murthy, Ch.S.N.
    An attempt has been made in this paper to investigate the influence on sound level due to drilling in rocks of varying physical properties i.e. compressive strength and abrasivity using jackhammer drill. For this purpose, a jackhammer drill setup was fabricated wherein the thrust applied can be varied while drilling vertical holes. The compressive strength and the abrasivity of various rock samples collected from the field were determined in the laboratory. A set of test conditions were defined for measurement of sound level of the jackhammer drill. Also, with the help of the experimental setup, vertical drilling was carried out on the rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. The results of this study indicate that, increase in thrust increases the sound level at higher midband frequencies in the noise spectrum. The study indicated the sound level near the drill rod to be 0.5 to 1.5 dB, 2.0 to 3.0 dB and 4.0 to 6.0 dB higher relative to that at the drill bit, the exhaust and the operator's position respectively at an air pressure of 5 kg/cm2 and 160 N thrust for all the rock samples tested. Both the thrust and air pressure were found to have a significant effect on the sound level produced by jackhammer drill at all the measurement locations. The study further shows that an increase in sound level of the order of 1.5 to 2.5 dB at the operator's position can occur with an increase in air pressure by 2 kg/cm2 at 160 N thrust and with an increase in compressive strength and decrease in abrasivity of rocks. Also, the increase in sound level at the operator's position with increase in compressive strength and decrease in abrasivity of rock is of the order of 1.0 to 2.0 dB. In order to maintain a constant penetration rate in the rocks, both the thrust and air pressure need to be increased with an increase in compressive strength and decrease in rock abrasivity. Therefore, increased compressive strength and lower abrasivity of rocks will require higher air pressure and thrusts to be applied to achieve an optimum penetration rate and therefore will result in higher sound level at the operator's position and at other measurement locations. © 2007 Institute of Noise Control Engineering.
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    Estimating rock properties using sound levels produced during drilling
    (Elsevier BV, 2009) Vardhan, H.; Adhikari, G.R.; Govinda Raj, M.
    An attempt has been made in this paper to experimentally investigate the estimation of rock properties like compressive strength and abrasivity using sound levels produced during drilling. The investigation was carried out on a laboratory scale using small portable pneumatic drilling equipment used in hard rock drilling. For this purpose, a pneumatic drill setup was fabricated for drilling vertical holes. The compressive strength and the abrasivity of various rock samples collected from the field were determined in the laboratory. A set of test conditions were defined for measurement of sound level of the pneumatic drill. Also, with the help of the experimental setup, vertical drilling was carried out on the rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. Results of this study indicate that sound level can be a promising tool in estimating rock properties during drilling. © 2008 Elsevier Ltd. All rights reserved.
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    Correlation between Petrographical and engineering properties of Ilkal granites, Karnataka
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Venkat Reddy, D.; Santosh, H.G.; Priyanka, K.
    Granitic rocks show a variety of engineering properties that may affect quarrying operations, slope stability, mining and the use of rock as a structural as well as architectural material. In present investigation, correlation analysis is carried out for experimental results to study the influence of mineralogical and textural characteristics on physical and strength properties using SPSS software. A variety of granitic rock samples from different parts of Ilkal were subjected to study petrographical and then same samples were tested to determine the specific gravity, bulk and dry density, water absorption, porosity, P-wave velocity, rebound hardness, point load strength index, uniaxial compressive strength and tensile strength. The study revealed that a petrographical characteristic like grain size, mineral composition and the bonding between each mineral of granitic rocks plays a major role in contributing the strength parameters. © 2011 Cafet-Innova Technical Society. All rights reserved.
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    Sound level produced during rock drilling vis-à-vis rock properties
    (2011) Rajesh Kumar, B.; Vardhan, H.; Govindaraj, M.
    The process of drilling, in general, always produces sound. Though sound is used as a diagnostic tool in mechanical industry, its application in predicting rock property is not much explored. In this study, an attempt has been made to estimate rock properties such as uniaxial compressive strength, Schmidt rebound number and Young's modulus using sound level produced during rotary drilling. For this purpose, a computer numerical controlled vertical milling centre was used for drilling holes with drill bit diameters ranging from 6 to 20. mm with a shank length of 40. mm. Fourteen different rock types were tested. The study was carried out to develop the empirical relations using multiple regression analysis between sound level produced during drilling and rock properties considering the effects of drill bit diameter, drill bit speed and drill bit penetration rate. The F-test was used to check the validity of the developed models. The measured rock property values and the values calculated from the developed regression model are fairly close, indicating that the developed models could be efficiently used with acceptable accuracy in prediction of rock properties. © 2011 Elsevier B.V.
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    A critical review on estimation of rock properties using sound levels produced during rotary drilling
    (CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2012) Masood; Vardhan, H.; Mangalpady, M.; Rajesh Kumar, B.
    This paper summarizes the critical review on estimation of rock properties using sound levels produced during rotary drilling. In this paper an overall emphasis has been made to summarize the importance of sound level produced during drilling by considering various parameters like drill bit speed, penetration rate, drill bit diameter, type of drill bit and equivalent sound level produced during drilling for the estimation of rock properties. Further an attempt has also made to include the application of ANN modeling and acoustic emission in estimating rock properties. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.
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    Terrain analysis and hydrogeochemical environment of aquifers of the southern west coast of Karnataka, India
    (2012) Honnanagoudar, S.S.; Venkat Reddy, D.; Mahesha, A.
    Dakshina kannada district is situated in peninsular region. The peninsula is composed of geologically ancient rocks of diverse original and most of them have undergone metamorphism. The early Precambrian tonalitic gneisses invaded by granites, granulites and dolerite dykes. Granulites are mostly restricted to areas south of Mangalore. High grade alumina rich (corundum bearing) metamorphic schists have been encountered and younger alkaline intrusive rocks like Aegerine syenites have been reported. There are five rivers and estuaries. Number of lineaments cut across each other and some lineaments are parallel to each other. The Arabian sea class is the largest among other land cover features in the study area. The river/tidal creek land cover appear as long irregular and sinous in outline. Mulki river, Netravati river, Gurupur river at southern terrain. The qualities of groundwater at sandy aquifer are good, lateritic/weathered gneissic rocks it is sweet. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.
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    Regression analysis and ANN models to predict rock properties from sound levels produced during drilling
    (Elsevier Ltd, 2013) Rajesh Kumar, B.; Vardhan, H.; Govindaraj, M.; Vijay, G.S.
    This study aims to predict rock properties using soft computing techniques such as multiple regression, artificial neural network (MLP and RBF) models, taking drill bit speed, penetration rate, drill bit diameter and equivalent sound level produced during drilling as the input parameters. A database of 448 cases were tested for determination of uniaxial compressive strength (UCS), Schmidt rebound number (SRN), dry density (?), P-wave velocity (Vp), tensile strength (TS), modulus of elasticity (E) and percentage porosity (n) and the prediction capabilities of the models were then analyzed. Results from the analysis demonstrate that neural network approach is efficient when compared to statistical analysis in predicting rock properties from the sound level produced during drilling. © 2012 Elsevier Ltd.
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    Laboratory Investigations on Percussive Drilling
    (Springer India sanjiv.goswami@springer.co.in, 2013) Kivade, S.B.; Murthy, C.S.N.; Vardhan, H.
    The laboratory investigation was carried out on ten rock samples using pneumatic drill with drill bits of different diameters. In general, the process of drilling always produces sound. Sound is generated from the bit-rock interface regardless of the material of the bit used in drilling. The predicted sound level and penetration rate are a product of the drill power and the physical properties of the rocks penetrated. Rock samples were collected from the field and physical properties of the rocks were determined in the laboratory. The sound level and penetration rates were correlated with the rock properties. The compressive strength and abrasivity exhibit strong correlations with the sound level and penetration rate. It was concluded that, among the rock properties included in this study, the compressive strength and abrasivity values are the dominant ones affecting the penetration rate and sound level of percussive drills. Though ten rock samples have been covered in this study, detailed analysis of only one of them is presented. © 2013, The Institution of Engineers (India).
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    Geomorphology and hydrogeology of coastal tracts of the Central West Coast of India
    (2013) Honnanagoudar, S.S.; Venkat Reddy, D.; Mahesha, A.
    Dakshina Kannada district which is a coastal district of Karnataka, spreads along the west coast of India covering coastal tract of about 40 km. Dakshina Kannada district is divided into three regions, low land, mid land and high land. The coast line is generally straight and followed the Dharwar rocks trending NNW-SSE.The rocks weathered fractured and jointed granitic gneisses and laterite varies from 10 m to 30 m. The thickness of coastal alluvium varies from 7 to 29 m. There are spits and beach ridges available in coastal tract. The Netravati river flow towards Mangalore where it joins Gurupur River and both the Rivers from common esture discharging into the sea. Gneissic rocks archaean age cover a major part of this region as basement rocks. These are elsewhere overlain by oligomictic quartz conglomerate belonging to Dharwar super group. The recent alluvium and colluvial deposits occur along the river bed and sea coast. The exposure of crystalline rock found as isolated hills along the shore and off shore. The black clay marine sediments with a thickness of 0.30 m to > 1m occur as lenses along the coast and in the deltaic islands. Its occurrence as marked at a depth ranges of 5 to 6 mbgl. The groundwater below the black clay horizons of coastal sediments found with high salinity, which marks the index bed for saline water and fresh water interface. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.