Conference Papers
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Item Assessment of objective based blast performance: Ranking system(2013) Sastry, V.R.; Ram Chandar, K.R.Rock fragmentation using chemical energy is commonly followed for fragmenting and displacing the rock mass in mining, civil and other excavation projects. In case of mines, the objective of rock fragmentation is to get a uniform sized material to suit the subsequent operations like loading, hauling and crushing. In case of civil engineering projects like canals, tunnels, it is to provide the space for some facilities and the material produced may not be having a specific use. In case of blasting near to the human habitats or important structures like dams, ground vibrations generated should be within permissible safe limits, along with proper fragmentation. Cost reduction is also a prime factor in all the cases. In general, assessment of blast performance refers to fragmentation assessment. However, based on the objective, the approach to blast design may be different. An attempt is made through this paper to discuss different blast performance assessment methods, through a case study and a ranking system is proposed. Field studies were carried out in a limestone mine in southern India, using eight controlled blasts by changing the initiation system, initiation pattern and maintaining same blast geometry parameters. Blast performance was assessed based on fragmentation using digital image processing technique, energy distribution, and productive yield and powder factors resulting from the blasts. Rankings were given to different blasts as per the performance.Item A Comparative Study on Using Laterite and Sandstone Aggregates on Mechanical Properties of Concrete(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Gayana, B.C.; Ram Chandar, K.R.; Reddy, K.R.Scarcity of natural aggregates in concrete construction is leading to explore the use of alternative materials, especially various industrial waste products. Mining industry is one such major source of waste materials. Sandstone, which is overlying coal seams, is the largest quantity of waste rock being produced by coal mining industry. Laterite is another waste comes from small scale quarries. An attempt is made to assess the use of laterite-GGBS and sandstone as partial replacement for sand in concrete. Sandstone samples were collected from the dumps of a coal mine in south India and laterite samples were collected from different quarries from the southwestern part of India. Various properties of mine waste samples were determined in the laboratory as per IS codes, the properties were found to be very close to that of natural river sand. Mix proportions were prepared for M20 grade concrete. Mechanical properties of concrete with different mixes (0, 25, 50, 75, and 100% replacement with sand) were determined and compared. As a result, the concrete mixes with the replacement of fine aggregates with 100% sandstone increased in strength properties i.e., compressive, splitting tensile, and flexural strength compared to laterite mixes, where the strength properties decreased with increase in replacement levels. This indicates that sandstone can be an effective replacement for the river sand in concrete. © 2021, Springer Nature Switzerland AG.Item Assessment of Structural Damage Due to Blasting in Hydro Power Tunnel(Springer Science and Business Media Deutschland GmbH, 2022) Naveen, G.C.; Sastry, V.R.; Ram Chandar, K.R.Excavation is a major activity in construction of mega underground hydropower project. Successful excavation of access and water conducting tunnels and caverns of different size and shapes by adopting highly economical and efficient method of excavation like drilling and blasting in extreme geological conditions makes the hydropower project a manmade marvel. The national codes which regulates the safety of structures while using explosives are successfully adopted where the tolerable limits for blast induced seismic waves are provided for different type of structures. This paper deals with impact of 9 m(W) and 8 m(H) tunnel blast induced seismic vibrations on the underground and surface concrete structures. The outcome of tunnel blasting with reference to peak particle velocity and related displacements gave a unique results where the seismic wave produced displacements up to 0.04 mm at large underground openings (250 m(L) × 18 m(W) × 59 m(H)) when compared to displacements of 0.016 mm in small openings of 9 m(W) × 8 m(H) with similar peak particle velocity levels of 20 mm/sec. These results subjected the structures which are located in the larger underground openings to lose their strength easily when compared to the structures located in small openings. Further, the structures located in the surface are more vulnerable to get damaged due to higher displacement recordings up to 0.123 mm. Experimental outcome was recorded for various blast design and results were further analyzed to optimize the blast parameters for successful control of blast induced vibration zone within 60 m. The relation between the structure locations where blast induced seismic wave propagates seems to play a key role in influencing on the structural damage, where less influence of peak particle velocity is observed. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Impact of Enhanced Production from the Opencast Coal Mines on Ambient Particulate Emissions(Springer Science and Business Media Deutschland GmbH, 2022) Podicheti, R.K.; Ram Chandar, K.R.Coal still continues to be the major source of energy needs. It is estimated that power sector alone would require about 900 Mt of coal by the year 2025. Such large quantity requires more surface mines causing the load on environment. Among the various environmental factors, air pollution is one of the most important parameters to be considered and the estimation of emissions from a mine at various stages of its operations is vital which helps in taking preventive measures against pollution. Given the significance of mining as a source of particulates, accurate characterization of emissions is important for the development of appropriate emission estimation techniques for use in modeling predictions and for regulatory decisions. Estimation of emissions in the ambient air quality with regard to enhanced production needs to be established regionally. Keeping this in view, two opencast coal mines in South India are selected to evaluate the emissions of PM10 and PM2.5 in the ambient air due to increased coal production and overburden removal. Emissions for these two mines have been studied from the year 2012 to 2019. It was observed that the PM10 values ranged from 152 to 229 µg/m3 in the core zone and 71 to 98.2 µg/m3in the buffer zone. Similarly, PM2.5 values ranged from 49.4 to 80.9 µg/m3in the core zone and 25.3 to 55.3 µg/m3 in the buffer zone. Particulate emissions have increased proportionately with respect to the quantity of coal produced and overburden removed. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Accurate Estimation for Stability of Slope and Partition Over Old Underground Coal Workings Using Regression-Based Algorithms(Springer Science and Business Media Deutschland GmbH, 2022) Dorthi, K.; Kumar, A.; Ram Chandar, K.R.Numerical modeling simulation has found to be best solution for predicting slope and partition stability over old underground coal workings. But it has taken huge time to complete a single simulation model. In this regard, machine learning-based framework is used to predict the stability of old galleries. A case study is taken up in opencast mine and simulation is carried out using numerical model and machine learning-based framework. Framework has shown an overall accuracy of 94–95% for different slope and partition stability. Framework shows a speedup of 2366 × against numerical simulator. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.