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 Zigbee based Wireless Data Acquisition System for monitoring of partition stability above old underground coal workings(Springer, 2020) Dorthi, K.; Bayyapu, N.; Ram Chandar, R.C.Conversion of old underground workings into opencast mines leads to rock displacement, collapse of partition, and slope failures some times. Continuous monitoring of slopes and partition is required to maintain the stability over old workings. Wireless sensor network is more suitable method for continuous monitoring, and it is cost-effective, two-way communication, and provides real-time monitoring and analysis of data. In this paper, development of a low-cost Zigbee based Wireless Data Acquisition System (WDAQ) is described. Field investigations were carried out in an opencast coal mine in south India to assess the strain and deformation for different partition thicknesses of 4.12m, 5.91m, 6.86m, 7.91m, 10.21m and 12.10m over old underground workings, due to the external load caused by the movement of Heavy Earth Moving Machinery (HEMM). Maximum strain and deformation were 387 × 10?6 and 2.41 mm for 4.12 m partition, respectively. It can be observed that the strain and deformation are decreased with increased partition thickness. This paper also describes that the validation of data based on Zigbee based WDAQ with conventional method of monitoring as well as numerical modeling. The data obtained using WDAQ is in close to the other two methods. The variation is around 5–19%. © 2020, Saudi Society for Geosciences.Item Comparison of model study with field implementation of gravity blind backfilling method to control subsidence induced disaster in abandoned underground coal mines(World Researchers Associations, 2023) Kumar, P.S.; Akhil, A.; Kumar, T.A.Blind hydraulic backfilling technique is used for subsidence control in underground coal mines. A laboratory size model of underground working was developed to understand backfilling process. Observations from model were utilized for backfilling process in one of the underground mines. This study describes the results obtained in the field investigation at an old abandoned waterlogged underground coal mine of Eastern Coalfields Limited (ECL), a subsidiary of Coal India Limited and their verification with the findings obtained in the laboratory scale model study carried out on a model of underground coal mine worked by board and pillar method. The relative influence of slurry concentration and flow rates on the areas of filling from a single inlet borehole has been discussed. The relative spread of sand in different directions has also been measured using a remotely operated underground vehicle mounted camera. The empirical relationships developed under field conditions have been found to be similar to those of laboratory model. © 2023, World Research Association. All rights reserved.Item Analysis of Fault’s Effect on the Highwall Stability of Medapalli Open Pit Coal Mine(Springer Science and Business Media Deutschland GmbH, 2023) Kumar Reddy, S.K.Mining operations can have a significant impact on the stability of the surrounding area. One example is the Medapalli open pit coal mine in southern India. The mine is a large excavation working at a depth of 165 m that can reach up to 200 m. The western side highwall has locked-up coal reserves in the mine, but concerns about the geologically disturbed regions have resulted in complications and significant challenges. Surface tension cracks around the excavation became visible in 2018, prompting intensive monitoring, protective measures, and numerous geotechnical analyses. The area, however, has a rich tectonic history, with faults interacting with soil movements. Proper geotechnical investigations were used in this work to analyse the stability of the highwall due to faults' effects on the area's reaction due to mining operations. The findings in the study highlighted the significance of flaws in the ground movement due to improper design of the highwall fault interaction area. The presence of the fault increases the likelihood of tensile cracks and subsidence at the highwall's surface level, significantly worsening the mining activities in the area. The analysis reveals that complex geological features, such as the presence of faults roughly parallel to the highwall slope profile, can exacerbate the mining operations in the surrounding environment. The recommended slope design with protective measures towards the west side disturbed highwall area helps safely excavate the western side highwall locked-up coal reserves in the Medapalli open pit mine. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Slope stabilization of coal mine overburden dumps: life cycle environmental sustainability assessment of alternatives(Springer Science and Business Media Deutschland GmbH, 2024) Kumar, A.; Nainegali, L.; Das, S.K.; Reddy, K.R.; Mishra, A.The stability of coalmine overburden dumps is a crucial aspect and often requires a slope stabilization method in place to prevent slope failures. Mechanical methods like benching, gabion wall construction, geogrid reinforcement, and biological methods like the use of vegetation can suffice the need for slope stabilization. In this study, a life cycle assessment of the above-mentioned methods was performed to obtain the environmental impacts through various midpoint impact categories considering a “cradle-to-site” assessment. The system boundary for each method was created using the involved activities and associated equipment and energy needs. The Ecoinvent 3.0 database and TRACI assessment method were used to perform the life cycle impact assessment using SimaPro software. The results show that the use of vegetation caused the least impact. The highest impact under the majority midpoint categories was caused by geogrid reinforcement followed by benching, which was mostly attributed to the geogrid production and OB handling activities, respectively. The carcinogenic, followed by ecotoxicity and fossil fuel depletions, were the most impacted categories for the mechanical methods, which may be due to the release of chemical pollutants during material production or handling. Adherence to the overburden dump management guidelines and the use of renewable sources of energy are the two major aspects that can drastically curb the emission load on the environment, thus inching towards the goal of sustainability while adopting slope stabilization measures for overburden dumps. Besides imparting stability, plants provide a diverse solution to the other ills associated with the overburden storage and management. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.Item Geotechnical Investigations of Coal Mine Waste Dump Material(World Researchers Associations, 2025) Harish, P.; Chandar, K.R.Mining is an essential activity for obtaining the raw materials required for infrastructure and energy needs. During the extraction of coal, a significant amount of overburden (OB) material is generated. Managing the overburden produced by mining activities demands a substantial land for disposal which can be quite challenging in limited spaces. Consequently, it becomes imperative to design safe coal mine OB dumps, optimizing the use of available ground space. The challenge of ensuring the stability of overburden dumps is directly linked to the geotechnical properties of these materials. Therefore, it is crucial to characterize the properties of the dump material accurately to assess its engineering properties reliably. The focus of this study is to outline the various testing procedures necessary for the proper characterization of dump materials to ensure the stability of the dumps. Additionally, the study provides an analysis of laboratory test data and presents typical results from a case study. © 2025, World Researchers Associations. All rights reserved.Item Root reinforcement of herbaceous vegetation for stabilization of coal mine overburden dump slopes(Springer Science and Business Media Deutschland GmbH, 2025) Kumar, A.; Nainegali, L.; Das, S.K.; Reddy, K.R.Slope instability of coal mine overburden dumps poses significant challenges to mining safety and environmental sustainability. This study investigates the potential for root reinforcement offered by herbaceous vegetation (Dendrocalamus strictus and Cymbopogon citratus) for enhanced slope stability. A series of pot experiments were conducted to grow grasses with the coal mine overburden material. The survival and growth of grasses in the nutrient-devoid overburden are critical because they directly impact the effectiveness of root reinforcement. Therefore, the effect of amendment quantity on plant growth was assessed. A direct shear box test was conducted on the bare and rooted samples using a fabricated internal shear test assembly to determine the strength. The higher peak shear stress and dilatancy angle observed for the rooted specimens were due to the high root tensile strength mobilizing the shear stresses. The results of shear tests were subsequently employed in limit equilibrium slope stability analyses where material heterogeneity was considered to account for uncertainties linked to material properties. The deterministic analysis provided insights into the expected improvements in slope stability due to root reinforcement, offering a baseline for comparison. Meanwhile, the probabilistic analysis considered the variability in material properties, thus providing a more comprehensive understanding of the uncertainty associated with the slope stability assessment regarding the reliability index and probability of failure. By combining experimental investigations with rigorous analytical approaches, this study enhances our understanding of how grassroots reinforcement can enhance the stability of coal mine overburden dumps. © The Author(s), under exclusive license to Springer-Verlag GmbH Germany, part of Springer Nature 2025.