Strata behavior in longwall mining at greater depths

Abstract

This thesis presents the overview of problems of underground coal mining at greater depth and reserve position of coal in India. Various strata control issues relate to stress distribution around the longwall panels at depths approaching 900m in different countries was discussed. Extent of abutment loading and need of advance support for more distances away from the longwall faces as compared to conventional practices at shallow depths is emphasized. Innovative design of barrier pillars at high stress conditions with yield pillars is illustrated. Mining options for various coalfields in India are presented.
Issues regarding mining techniques, or need of innovative techniques is critically evaluated based on the experiences of different countries and the design implemented for safe and economically viable mining for the extraction of seams at greater depths. Strata behaviour monitoring of longwall panel at GDK 10A Incline (SCCL) is illustrated along with the instrumentation used for monitoring, convergence, and load over the supports atmain gate and tail gate roads.Increase of load on supports observed between 5Te. to 10Te., the roof to floor convergence of 42mm in tail gate was recorded, and maximum of 88mm in main gate was recorded, and maximum stress over the pillar of16.45 kg/cm2 was recorded in the main gate, and maximum of 7.1 kg/cm2 in tail gate was recorded.