Study of Support System and Strata Behaviour Analysis Around Underground Workings in Coal Deposits

Abstract

The estimation of vertical stress and its distribution over the underground mine workings is of prime importance. In this project work their estimation is been done with the help of numerical modeling by simulating the workings. Study and analysis of the stress distribution around development and depillaring workings in coal mines and vertical stress estimation is done.

The working has been modelled by writing a program code in FLAC5.0. The modelling is done in stages involving driving of galleries (development) to form three pillars and then the extraction of these pillars (depillaring) by slicing, then complete extraction to form ribs further followed by the judicious rob and burst of rib. The model is run in each of these stages to get the vertical stress distribution.

From the analysis of stress distribution through numerical model (FLAC5.0) for a depth cover of 95.5m following maximum vertical stress was observed as Maximum vertical stress over the pillar during development is about 3 MPa, Maximum vertical stress over the stook during development is about 4 Mpa and Maximum vertical stress over the rib during development is about 7 Mpa.

The outcome of the results show that the ultimate vertical stress increases considerably with increase in the depth cover and get concentrated over the area of excavation with high stress concentration over the pillars, stooks and ribs above the normal stress under the given depth cover.