Analysis of Subsidence and Stability of Pillars in A Coal Mine

Abstract

The significance of mining will be certainly immense to human development. Truly, as one of the biggest of human endeavours, Mining and its improvements relate nearly with social progress. One of underground mining methods is the Bord and Pillar Method of Mining and this method is one of the oldest Mining Methods. By the help of Bord and Pillar Mining, extraction will be high. The key to successful Bord and Pillar Mining is selecting the optimum pillar size and stability of the pillar. If the pillars are too small the mine will collapse. If the pillars are too large then significant quantities of valuable material will be left behind reducing the profitability of the mine. The issues relating to the stability of pillars and Subsidence from it will be a major concern now-a-days. The most critical parameter before outlining and stability of pillars will be the Safety component. The primary objective of this project is to increase the extraction proportion with the help of stability of created pillars and subsidence control and Based on laboratory testing of coal samples, empirical and numerical modelling studies related to the stability of the pillar and analysis of observation data on subsidence profiles for underground coal mine, the following conclusions are done. Field observations at Kumda underground mine indicated stability of the pillars without any perceptible side spilling and crushing. Uniaxial compressive strength, triaxial testing of coal samples indicated UCS, cohesion(C) and internal friction angle(∅) of 27.9 MPa, 1.85 MPa and 300 respectively. Empirical and numerical modelling using two dimensional continuum analyses indicated the maximum stress of 5 MPa over the pillar and safety factor exceeding 2 confirming to the qualitative observation of stability of the pillar. Maximum subsidence at 1.58 m was observed over the over the extracted panels with a subsidence factor of 0.63 for the depillaring panels with the width and depth of 64 m-14 m, 30 m-45.5 m respectively The significance of mining will be certainly immense to human development. Truly, as one of the biggest of human endeavours, Mining and its improvements relate nearly with social progress. One of underground mining methods is the Bord and Pillar Method of Mining and this method is one of the oldest Mining Methods. By the help of Bord and Pillar Mining, extraction will be high. The key to successful Bord and Pillar Mining is selecting the optimum pillar size and stability of the pillar. If the pillars are too small the mine will collapse. If the pillars are too large then significant quantities of valuable material will be left behind reducing the profitability of the mine. The issues relating to the stability of pillars and Subsidence from it will be a major concern now-a-days. The most critical parameter before outlining and stability of pillars will be the Safety component. The primary objective of this project is to increase the extraction proportion with the help of stability of created pillars and subsidence control and Based on laboratory testing of coal samples, empirical and numerical modelling studies related to the stability of the pillar and analysis of observation data on subsidence profiles for underground coal mine, the following conclusions are done. Field observations at Kumda underground mine indicated stability of the pillars without any perceptible side spilling and crushing. Uniaxial compressive strength, triaxial testing of coal samples indicated UCS, cohesion(C) and internal friction angle(∅) of 27.9 MPa, 1.85 MPa and 300 respectively. Empirical and numerical modelling using two dimensional continuum analyses indicated the maximum stress of 5 MPa over the pillar and safety factor exceeding 2 confirming to the qualitative observation of stability of the pillar. Maximum subsidence at 1.58 m was observed over the over the extracted panels with a subsidence factor of 0.63 for the depillaring panels with the width and depth of 64 m-14 m, 30 m-45.5 m respectively