Browsing by Author "Nair, R."

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    Analysis of stress distribution in longwall barrier: a case study
    (2010) Sastry, V.R.; Nair, R.
    This paper presents results of a detailed study on the stress distribution in longwall barriers during extraction of coal in an underground mine. Analysis was carried out on the stress obtained at different locations in the barrier using finite element modelling and field monitoring. Results indicated that the zone of barrier lying in goaf experienced higher stress when compared with barrier lying in the solid zone. Stress in the region of barrier lying between 10 m ahead of face and 40 m behind the face (barrier section lying in goaf) was found to be the most critical in the design of barrier. © 2010 Inderscience Enterprises Ltd.
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    Effect of lower seam old workings on longwall powered supports in upper seam
    (2007) Sastry, V.R.; Nair, R.; Venkat, Ramaiah, M.S.
    Load bearing capacity of powered roof supports is a key issue in the design of longwall panels. The existence of multiple seams in a given project may involve over mining or undermining operations across different seams. The paper envisages variation in stress distribution and load on powered supports in the upper seam longwall panel due to the presence of already mined out bottom seam consisting goaf, pillars and openings through detailed field investigations in an underground coal mine followed by finite element modeling study. Studies revealed that for every 40 m of face retreat, the load from the roof gradually gets transferred from the panel to the goaf. Stress distribution over chock shields was considerably affected when the face in upper seam reached 15-25m zone above the openings in lower seam. The presence of barrier in the bottom seam increases load on the chock shields in longwall panel of upper seam. � 2007 Taylor & Francis Group, London.
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    Effect of lower seam old workings on longwall powered supports in upper seam
    (2007) Sastry, V.R.; Nair, R.; Venkat Ramaiah, M.S.
    Load bearing capacity of powered roof supports is a key issue in the design of longwall panels. The existence of multiple seams in a given project may involve over mining or undermining operations across different seams. The paper envisages variation in stress distribution and load on powered supports in the upper seam longwall panel due to the presence of already mined out bottom seam consisting goaf, pillars and openings through detailed field investigations in an underground coal mine followed by finite element modeling study. Studies revealed that for every 40 m of face retreat, the load from the roof gradually gets transferred from the panel to the goaf. Stress distribution over chock shields was considerably affected when the face in upper seam reached 15-25m zone above the openings in lower seam. The presence of barrier in the bottom seam increases load on the chock shields in longwall panel of upper seam. © 2007 Taylor & Francis Group, London.
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    Stress distribution on longwall barrier pillar due to goaf formation during extraction
    (2009) Sastry, V.R.; Nair, R.
    Mechanised longwall mining is a sustainable option to achieve higher production from underground coal seams. Judicious design of underground longwall panel requires understanding of stress distribution on barrier pillars during different stages of extraction. The paper presents a study of stress distribution in and around barrier pillars for the condition wherein extraction in both the adjacent panels are completed and goaf exists on either side of the pillar. Finite element analysis was taken up for parametric study of varying widths of barrier pillar and different degrees of compaction of broken material in the goaf formed during extraction. Analysis revealed that the stress transferred on pillar decreased as the width of barrier pillar increased. Stress intensity at pillar edges was higher than that at centre of the pillar. Stress distribution in the strata lying above barrier pillar was influenced considerably by the compaction of goaf material.
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    Study of behaviour of workings in longwall panel based on field instrumentation
    (2009) Sastry, V.R.; Nair, R.
    The paper presents field monitoring study of two adjacent longwall panels based on stress measurements in longwall block and barrier, load transferred on to the gate roads and convergence measurements in the gate roads during face retreat in the panels. Results indicated that the section of barrier lying in the goaf experienced higher abutment stress when compared with the section lying ahead of face. There was a transfer of load in gate roads ahead of face after the occurrence of roof fall in goaf. Maximum cumulative convergence of more than 8 mm was observed in the gate roads during weightings. © 2009 Inderscience Enterprises Ltd.