System calibration • Statutory thresholdsDEMO SYNTHETICCMR 2017 Reg 112 Compliant
Geotechnical Thresholds & Colliery Stratigraphy Parameters
Operational ground stability limit criteria, permissible subsidence gradients, and telemetry transducer calibration matrix for Jharia Coalfield.
Regulatory standard
DGMS CMR 2017
Circular (Coal) No. 04 of 2017
Critical evac slope
10 mm/m
Mandatory withdrawal trigger
Seam classification
Degree III Gassy
Flameproof Ex d I / Ex ia I required
Telemetry channels
5 Physical Types
Tilt, Disp, Vib, Strain, Acoustic
1. Statutory ground movement thresholds (DGMS CMR 2017)
Calibrated trigger thresholds for escalating early warnings and emergency shift evals
| Transducer modality | Normal baseline | Advisory limit | Watch threshold | Warning limit | Critical evacuation limit |
|---|---|---|---|---|---|
| Biaxial tilt slope | < 1.0 mm/m | 1.0 - 1.5 mm/m | 1.5 - 2.0 mm/m | 2.0 - 3.0 mm/m | > 3.0 mm/m |
| Tensile strain | < 0.5 mm/m | 0.5 - 1.0 mm/m | 1.0 - 1.5 mm/m | 1.5 - 2.0 mm/m | > 2.0 mm/m |
| Cumulative displacement | < 20 mm | 20 - 40 mm | 40 - 60 mm | 60 - 80 mm | > 80 mm |
| Vibration velocity (PPV) | < 0.5 mm/s | 0.5 - 1.0 mm/s | 1.0 - 2.0 mm/s | 2.0 - 5.0 mm/s | > 5.0 mm/s |
Colliery stratigraphic profile
Colliery designationBhowra-West Colliery (Demo Mine)
Mining methodBord & Pillar with Hydraulic Sand Stowing
Active coal seamSeam VII (Average thickness: 6.2m)
Depth of cover240m to 285m below surface
Overburden strataBarakar Formation Sandstone / Shale