GROUND MOVEMENTS OVER LONGWALL WORKINGS IN THE KAMPTEE COALFIELD, INDIA

Subsidence investigations were conducted over three superimposed longw all panels in the Kamptee coalfield of Central India. The extracted co ntiguous seams were lying below a water bearing unconfined aquifer. Fi lling of voids with sand hydraulically was practised to avoid a sudden inrush of water into the under-ground workings through ground-movemen t induced cracks. The non-effective width of extraction varied between 0.55 and 0.61 times the thickness of intact rockmass in the overburde n. The maximum subsidence, slope, compressive and tensile strains were 9% of extraction thickness, 6.1, 6.6 and 5.3 mm m(-1), respectively. The angle of draw was influenced by the presence of a fault and compos ition of superincumbent strata. The ground movements lowered water tab le by 6.5 m in the unconfined aquifer due to the mining. (C) 1998 Else vier Science B.V. All rights reserved.