International Journal of Earth Sciences and Engineering

Samir K. Pal ¹, Anup K. Tripathi ², Susmita Panda ¹

Affiliations
1 Department of Mining Engineering, I.I.T. Kharagpur-721302, West Bengal, IN
2 Department of Mining Engineering, N.I.T. Surathkal-575025, Karnataka, IN

Abstract

Blind hydraulic backfilling is a commonly used technique for subsidence control of the strata over unapproachable water-logged underground excavations. In an investigation performed earlier, studies were carried out on simple gravity hydraulic blind backfilling in laboratory scale within a fully transparent model of a section of underground coal mine worked on bord and pillar method. Subsequently, field investigation at an abandoned underground waterlogged coal mine of Eastern coalfields Limited, a subsidiary of Coal India Limited, has been taken up to verify the findings obtained in the laboratory scale model study. The paper describes the field arrangements made for the backfilling process, and the use of remotely operated vehicle mounted camera and its sonar imaging facility for mapping of the abandoned underground waterlogged mine and for monitoring the progress of the sand filling during consecutive stages of the backfilling process.

Keywords

Underground Coal Mine Subsidence, Bord and Pillar Mining, Gravity Blind Backfilling, Remotely Operated Vehicle Mounted (ROV) Camera, Sonar Imaging.

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Samir K. Pal ¹, Subir K. Mukhopadhyay ¹, Susmita Panda ¹, Anup K. Tripathi ²

Affiliations
1 Department of Mining Engineering, I.I.T., Kharagpur-721302, West Bengal, IN
2 Department of Mining Engineering, N.I.T. Surathkal-575025, Karnataka, IN

Abstract

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.

Keywords

Gravity Blind Backfilling, Slurry Flow Rates, Sand Concentration, Data Acquisition, Pressure Signature, Pre-Jamming Indication.

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