Behaviour of Shield Support in Longwall Mining

Abstract

Field observation were conducted on behaviour of chock shield support of capacity 800T during extraction of longwall panel no. 3D2 at 250m depth and 150m face length of GDK 10A Incline, Singareni Collieries Company Limited. Chock leg pressures and leg closures were regularly monitored at different stages of extraction of longwall panel. During extraction of the panel, maximum leg closure and pressure on the chock shield were 600mm and 490bar, respectively (not on all chocks). Setting and yielding pressures were 300bar and 400bar corresponding to setting load and yielding load 600T and 800T, respectively.During major fall condition, 27% of chock shields were loaded upto 800T. During normal periods, maximum load was about 640T. Parametric studies for depth covers of 150m to 1200m for the face advance of 6m to 150m was simulated in 2D numerical model. At each depth, a fall in vertical stress was found between 80 m to 100 m face advance indicating major roof falland for 250 m depth cover, it was varying from 6 MPa to 4.5 MPa. Vertical stress and roof sag above the support was increasing as the depth was varying from 150 m to 1200m and maximum found was 50MPa and 1500 mm respectively at 1200 m depth and 150m face advance.