Faculty Publications
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Item Model studies on the efficiency of gravity blind backfilling method and evaluation of a pre-jamming indication parameter(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Pal, S.K.; Mukhopadhyay, S.K.; Panda, S.; Tripathi, A.K.This paper discusses experimental research on a fully transparent scaled model of a section of a Bord and Pillar mine working carried out to study in detail the effectiveness of hydraulic blind backfilling as a solution to reduce subsidence problem above old underground water-logged coal mines. The relative influence of sand and water flow rates on the areas of filling from a single inlet point has been studied in detail. Automatic data acquisition system was installed in the model to continuously record the sand and water flow rates along with the inlet pressure of slurry at the entrance of the model. Pressure signature graphs have been plotted directly with the help of computer. Pressure signature analyses for various slurry flow rates and sand concentrations have been carried out. Investigation has also been carried out on evaluation of a pre-jamming indication parameter, which could be used for indication of the final stage of filling. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.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.Item Sonar mapping of abandoned water-logged underground coal mine and backfilling operation using underwater camera(Inderscience Publishers, 2021) Pal, S.K.; Tripathi, A.K.; Panda, S.; Palaniappan, S.K.The paper describes mine mapping and backfilling work carried out during field experimentations on simple hydraulic gravity blind backfilling method for the stabilisation of ground above old abandoned waterlogged underground coal mine of Eastern Coalfields Limited (ECL), India. The section of the abandoned mine to be backfilled was explored using the underwater remote operated vehicle (ROV) camera before actual backfilling work. The use of sonar imaging facility of the ROV camera for mapping of the underground waterlogged area to be backfilled is described. The plotting of gradual progress of sand bed as the filling progressed in different stages through different boreholes as monitored from surrounding camera boreholes is also described. © © 2021 Inderscience Enterprises Ltd.