Faculty Publications
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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 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.