Faculty Publications
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Item Prediction of uniaxial compressive strength, tensile strength and porosity of sedimentary rocks using sound level produced during rotary drilling(2011) Rajesh Kumar, B.R.; Vardhan, H.; Govindaraj, M.The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength, tensile strength and percentage porosity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of various predictor variables. Predictor variables selected for the multiple regression model are drill bit diameter, drill bit speed, penetration rate and equivalent sound level produced during rotary drilling (Leq). The constructed models were checked using various prediction performance indices. Consequently, it is possible to say that the constructed models can be used for practical purposes. © Springer-Verlag 2011.Item Investigation of Noise Level and Penetration Rate of Pneumatic Drill vis-à-vis Rock Compressive Strength and Abrasivity(Springer India sanjiv.goswami@springer.co.in, 2014) Kivade, S.B.; Murthy, Ch.S.N.; Vardhan, H.In this paper, detailed studies were carried out to determine the influence of rock properties on the sound level produced during pneumatic drilling. Further, investigation was also carried out on the effect of thrust, air pressure and compressive strength on penetration rate and the sound level produced. For this purpose, a fabricated pneumatic drill set up available in the institute was used. Rock properties, like compressive strength and abrasivity, of various samples collected from the field were determined in the laboratory. Drilling experiments were carried out on ten different rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. It was observed that, very low thrust results in low penetration rate. Even very high thrust does not produce high penetration rate at higher operating air pressures. With increase in thrust beyond the optimum level, the penetration rate starts decreasing and causes the drill bit to ‘stall’. Results of the study show that penetration rate and sound level increases with increase in the thrust level. After reaching the maximum, they start decreasing despite the increase of thrust. The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength and abrasivity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of predictor variables. © 2014, The Institution of Engineers (India).Item ANN Models for Prediction of Sound and Penetration Rate in Percussive Drilling(Springer India sanjiv.goswami@springer.co.in, 2015) Kivade, S.B.; Murthy, C.S.N.; Vardhan, H.In the recent years, new techniques such as; Artificial Neural Network (ANN) were employed for developing of the predictive models to estimate the needed parameters. Soft computing techniques are now being used as alternate statistical tool. In this study, ANN models were developed to predict rock properties of sedimentary rock, by using penetration and sound level produced during percussive drilling. The data generated in the laboratory investigation was utilized for the development of ANN models for predicting rock properties like, uniaxial compressive strength, abrasivity, tensile strength, and Schmidt rebound number using air pressure, thrust, bit diameter, penetration rate and sound level. Further, ANN models were also developed for predicting penetration rate and sound level using air pressure, thrust, bit diameter and rock properties as input parameters. The constructed models were checked using various prediction performance indices. ANN models were more acceptable for predicting rock properties. © 2015, The Institution of Engineers (India).Item Estimation of Rock Strength Properties Using Selected Mechanical Parameters Obtained During the Rotary Drilling(Springer, 2019) Lakshminarayana, C.R.; Tripathi, A.K.; Pal, S.K.During the preliminary stage of rock engineering projects, the estimation of mechanical properties of rocks is most often required. The requirement of a large number of high-quality rock core samples is the major drawback when the mechanical rock properties are to be determined in a well-established rock mechanics laboratory. In this study, an attempt is made to estimate the uniaxial compressive strength and Brazilian tensile strength of sedimentary rocks using the selected mechanical drilling operating parameters obtained during the rotary drilling. The operating measured parameters such as the weight on bit or thrust and the vibration frequency induced at machine or drill head were acquired using the drill tool dynamometer and sound/vibration data acquisition system, respectively. The mathematical models were developed considering the drilling operational parameters (drill bit diameter, drill bit speed and penetration rate) and measured mechanical parameters (thrust and vibration frequency). The prediction potential of the developed models was assessed by the prediction performance indices. The outcome results revealed that the developed mathematical model using the approached method is significant and can be conveniently used for the estimation of mechanical properties of rocks during the rotary drilling. © 2019, The Institution of Engineers (India).Item Prediction of Mechanical Properties of Sedimentary Type Rocks Using Rotary Drilling Parameters(Springer, 2020) Lakshminarayana, C.R.; Tripathi, A.K.; Pal, S.K.The estimation of strength properties of sedimentary rocks is most often needed during the preliminary phase of many rock engineering projects carrying out in sedimentary regions. The main drawback of determining the rock properties in a test center is the requirement of the number of superior quality rock core specimens. In this experimental investigation, the uniaxial compressive strength (UCS) and tensile strength of sedimentary rocks are estimating using well-identified drilling variables and acoustic parameters obtained during the rotary type rock drilling. The drilling variables such as thrust, torque, and vibration parameters are used to develop the mathematical models of strength properties of rock. A drill type dynamometer was used to measure the drilling variables, and the vibration parameter would measure using the NI-9234 data acquisition system. The prediction efficiency of the mathematical model is evaluating using performance indices. Results show that the used experimental method can estimate the considered responses (UCS and tensile strength) with the acceptable percentage errors of 10.52% and 11.27% respectively, and may be useful to measure the UCS and BTS of sedimentary rocks in a laboratory capacity without test core samples. © 2020, Springer Nature Switzerland AG.Item Rock strength characterization using measurement while drilling technique(Springer, 2020) Lakshminarayana, C.R.; Tripathi, A.K.; Pal, S.K.The approximation of strength properties of rocks most often requires during the preliminary phase of any engineering projects related to rock mechanics. The main disadvantage of evaluating the rock properties in a testing laboratory is the prerequisite for high-quality rock core with many numbers. In this empirical method, the essential strength properties of rocks would measure during the rock drilling process using some identified machine variables along with the acoustic parameter. The machine operating variables such as thrust and torque and acoustic vibration parameter collecting at the machine head were used to develop rock strength models. A drill-type dynamometer was employed to gauge the machine variables and the NI-9234 data acquisition system for gauging the vibration parameter. The evaluation of the mathematical models for their efficiency shows that the applied empirical approach could determine the strength properties with fewer errors and can use as an alternative method for measuring the compressive and tensile strength of sedimentary rocks in the laboratory without using core samples. © 2020, Indian Geotechnical Society.