Factory of safety vs depth in a bord and pillar working

*Factor of Safety (FoS) in Mining*

The Factor of Safety (FoS) is a critical parameter in mining, ensuring the stability and safety of underground excavations. It's defined as the ratio of the ultimate strength of the rock or pillar to the actual stress imposed on it. A higher FoS indicates a safer design.

*Bord and Pillar Method*

The Bord and Pillar method is a widely used underground mining technique, particularly in coal and iron ore mines. It involves:

1. *Development*: Extracting coal or ore from the seam, leaving behind pillars to support the roof.
2. *Depillaring*: Removing the pillars, allowing the roof to collapse behind the advancing face.

*Key Components*

1. *Bords*: Narrow, excavated areas along the strike direction.
2. *Pillars*: Rectangular or square-shaped blocks of rock left between bords to support the roof.
3. *Stops*: Small, isolated areas of extraction.
4. *Headings*: Narrow, advancing tunnels along the strike direction.

*Design Considerations*

1. *Pillar size and spacing*: Optimized to ensure stability and minimize waste.
2. *Roof support*: Provided by pillars, rock bolts, or steel arches.
3. *Floor management*: Ensuring a stable floor to prevent subsidence.
4. *Ventilation*: Maintaining adequate airflow to prevent gas accumulation.

*Advantages*

1. *Flexibility*: Allows for adjustments in response to changing geological conditions.
2. *Low capital costs*: Compared to other underground mining methods.
3. *High extraction rates*: Enables rapid coal or ore removal.

*Disadvantages*

1. *Low recovery rates*: Pillars remain in place, reducing overall extraction.
2. *Safety concerns*: Risk of pillar failure, roof collapse, and gas accumulation.
3. *Environmental impact*: Subsidence and surface damage possible.

*Factor of Safety in Bord and Pillar Mining*

The FoS is critical in Bord and Pillar mining, as it directly affects the stability of the pillars and the overall safety of the mine. A higher FoS ensures that the pillars can withstand stress and prevent collapse. The FoS is calculated based on factors such as:

1. *Pillar strength*: Determined by rock type, size, and shape.
2. *Stress*: Caused by weight, geological conditions, and extraction activities.
3. *Pillar spacing*: Influences the distribution of stress and stability.

By maintaining a suitable FoS, miners can ensure the stability of the Bord and Pillar system, minimizing risks and maximizing efficiency. Regular monitoring and adjustments to the design and operation are essential to maintain a safe and productive mining environment.

1. REPORTONFACTOROFSAFETYVsDEPTHINABORDANDPILLAR
WORKING
Submitted by: -Vikash Kumar
RollNo.-2008053
Reg. No.-20030510050
Semester–5
th
Mining Engineering Department, BIT SINDRI
Submitted to: -Prof. Roshan Kumar

2. ARMPS, 12-14-2022, 23:12:20 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................90 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................26 (m)
AMZ set automatically
Pressure Arch Factor...................................1
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 6.05
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............0.9
AMZ Breadth.............................26.0 (m)
AMZ Area................................2704.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............6.19E+06 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................6.19E+06
TOTAL DEVELOPMENT.......................6.19E+06
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.

3. ARMPS, 12-14-2022, 23:12:20 Page: 2
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 3.75E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

4. ARMPS, 12-14-2022, 23:15:06 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................120 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................30 (m)
AMZ set automatically
Pressure Arch Factor...................................1
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 4.54
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............1.2
AMZ Breadth.............................30.0 (m)
AMZ Area................................3120.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............9.53E+06 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................9.53E+06
TOTAL DEVELOPMENT.......................9.53E+06
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.

5. ARMPS, 12-14-2022, 23:15:06 Page: 2
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 4.32E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

6. ARMPS, 12-14-2022, 23:15:34 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................150 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................34 (m)
AMZ set automatically
Pressure Arch Factor...................................1
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 3.63
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............1.4
AMZ Breadth.............................34.0 (m)
AMZ Area................................3536.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............1.35E+07 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................1.35E+07
TOTAL DEVELOPMENT.......................1.35E+07
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.

7. ARMPS, 12-14-2022, 23:15:34 Page: 2
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 4.90E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

8. ARMPS, 12-14-2022, 23:16:37 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................180 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................37 (m)
AMZ set automatically
Pressure Arch Factor...................................1
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 3.02
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............1.7
AMZ Breadth.............................37.0 (m)
AMZ Area................................3848.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............1.76E+07 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................1.76E+07
TOTAL DEVELOPMENT.......................1.76E+07
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.

9. ARMPS, 12-14-2022, 23:16:37 Page: 2
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 5.33E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

10. ARMPS, 12-14-2022, 23:16:59 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................210 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................40 (m)
AMZ set automatically
Pressure Arch Factor...................................0.8
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 3.24
[WARNINGS]
The Pressure Arch loading model used in ARMPS v6 was derived from
analysis of case history data from the Western and Central
Appalachian coalfields in the US. The overburden rock in these two
coalfields is relatively strong. No research has been conducted to
test the applicability of the pressure arch loading model in other
coalfields.
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............2.0
AMZ Breadth.............................40.0 (m)
AMZ Area................................4160.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............2.22E+07 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................1.78E+07
TOTAL DEVELOPMENT.......................1.78E+07
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front

11. ARMPS, 12-14-2022, 23:16:59 Page: 2
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 5.76E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

12. ARMPS, 12-14-2022, 23:17:20 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................240 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................43 (m)
AMZ set automatically
Pressure Arch Factor...................................0.77
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 2.95
[WARNINGS]
The Pressure Arch loading model used in ARMPS v6 was derived from
analysis of case history data from the Western and Central
Appalachian coalfields in the US. The overburden rock in these two
coalfields is relatively strong. No research has been conducted to
test the applicability of the pressure arch loading model in other
coalfields.
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............2.3
AMZ Breadth.............................43.0 (m)
AMZ Area................................4472.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............2.73E+07 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................2.10E+07
TOTAL DEVELOPMENT.......................2.10E+07
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front

13. ARMPS, 12-14-2022, 23:17:20 Page: 2
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 6.19E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

14. ARMPS, 12-14-2022, 23:17:42 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................270 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................45 (m)
AMZ set automatically
Pressure Arch Factor...................................0.73
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 2.76
[WARNINGS]
The Pressure Arch loading model used in ARMPS v6 was derived from
analysis of case history data from the Western and Central
Appalachian coalfields in the US. The overburden rock in these two
coalfields is relatively strong. No research has been conducted to
test the applicability of the pressure arch loading model in other
coalfields.
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............2.6
AMZ Breadth.............................45.0 (m)
AMZ Area................................4680.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............3.22E+07 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................2.35E+07
TOTAL DEVELOPMENT.......................2.35E+07
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front

15. ARMPS, 12-14-2022, 23:17:42 Page: 2
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 6.48E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

16. ARMPS, 12-14-2022, 23:18:00 Page: 1
ARMPS module build: 6.2.02
Project File: Untitled
Units: (m) (kPa) (kN)
[PROJECT TITLE]
[PROJECT DESCRIPTION]
[DEVELOPMENT GEOMETRY PARAMETERS]
Entry Height...........................................3 (m)
Depth of Cover.........................................300 (m)
Crosscut Angle.........................................90 (deg)
Entry Width............................................4.4 (m)
Number of Entries......................................5
Crosscut Spacing.......................................26 (m)
Center to Center Distance #1...........................26 (m)
Center to Center Distance #2...........................26 (m)
Center to Center Distance #3...........................26 (m)
Center to Center Distance #4...........................26 (m)
[DEFAULT PARAMETERS]
In Situ Coal Strength..................................6.21 (MPa)
Unit Weight of Overburden..............................25.45 (kN/m3)
Breadth of AMZ.........................................48 (m)
AMZ set automatically
Pressure Arch Factor...................................0.7
Pressure Arch Factor set automatically
[RETREAT MINING PARAMETERS]
Loading Condition..................DEVELOPMENT LOAD (NO NEARBY GOB)
[ARMPS STABILITY FACTORS]
Development.................................. 2.59
[WARNINGS]
The Pressure Arch loading model used in ARMPS v6 was derived from
analysis of case history data from the Western and Central
Appalachian coalfields in the US. The overburden rock in these two
coalfields is relatively strong. No research has been conducted to
test the applicability of the pressure arch loading model in other
coalfields.
[DATA ABOUT THE ACTIVE MINING ZONE (AMZ)]
Panel Width.............................104.0 (m)
Depth to Panel Width Ratio..............2.9
AMZ Breadth.............................48.0 (m)
AMZ Area................................4992.0 (m)*(m)
Extraction Ratio within AMZ.............0.31
Tributary Area Load on AMZ..............3.81E+07 (kN)
DEVELOPMENT LOADINGS ON AMZ (kN)
Tributary Area*.........................2.67E+07
TOTAL DEVELOPMENT.......................2.67E+07
*Adjusted by Pressure Arch Factor
R-Factor for front abutment is the percent of the total front

17. ARMPS, 12-14-2022, 23:18:00 Page: 2
abutment load that is applied to the AMZ.
R-Factor for side abutment is the percent of the total side abutment
load that is applied to the barrier pillar (the remainder is applied
to the AMZ).
LTRANSBAR is the load transferred to the AMZ from the barrier pillar
between the side and active gob if the barrier's SF is less than 1.5.
LTRANSREM is the load transferred to the AMZ from the remnant barrier
between the side and active gob if the remnant's SF is less than 1.5.
[PILLAR PARAMETERS]
PILLAR ENTRY MINIMUM MAXIMUM
CENTER DIMENSION DIMENSION
(m) (m) (m)
1 26.00 21.60 21.60
2 26.00 21.60 21.60
3 26.00 21.60 21.60
4 26.00 21.60 21.60
PILLAR AREA STRENGTH LOAD-BEARING
CAPACITY
(m)*(m) (kPa) (kN)
1 4.67E+02 20070.72 9.36E+06
2 4.67E+02 20070.72 9.36E+06
3 4.67E+02 20070.72 9.36E+06
4 4.67E+02 20070.72 9.36E+06
TOTAL LOAD-BEARING CAPACITY OF PILLARS WITHIN AMZ: 6.92E+07 (kN)
To view the distribution of Pillar Load Bearing Capacity
select 'View Plots->Settings->Pillar Load Bearing Capacity'
[BARRIER PILLAR PARAMETERS]
***none***
[REMNANT PILLAR AND LEAVE PILLAR PARAMETERS]
***none***

18. Result: -
The Factor of Safety gradually decreases with increase in depth as per the data of
Hariajam Underground mines which lies in Mugma area of Eastern coalfields Limited,
which is one of the subsidiaries of Coal India Limited.
Depth of
Cover(m)
Factor of Safety
(FOS)
90 6.05
120 4.54
150 3.63
180 3.02
210 3.24
240 2.95
270 2.76
300 2.59


Fig: - Variation of Factor of Safety with Depth of cover(m)
6.05
4.54
3.63
3.02
3.24
2.95
2.76
2.59
FOS = 108.99(DEPTH)
-0.663
R² = 0.9403
0
1
2
3
4
5
6
7
0 50 100 150 200 250 300 350
Factor of Safety(FOS)
Depth of Cover(m)
Factor of Safety(FOS) Vs Depth of Cover