🧱 Roof Support Systems & DGMS Safety Rules – DGMS Exam Notes 

                        Introduction

Roof support is one of the most vital safety aspects in underground mines.
A weak or unsupported roof can lead to falls of ground (FOG) — a major cause of fatalities in coal and metal mining.
Under CMR 2017 Reg. 99–106, DGMS mandates systematic roof support plans, testing, and supervision to ensure stability of working places.

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⚙️ Objectives of Roof Support

• Prevent collapse of mine roof or sides.
• Control strata movement during extraction.
• Protect workers and equipment.
• Maintain safe access routes and ventilation passages.

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🔩 Types of Roof Support Systems 

  1. Temporary Supports

• Props: Wooden or steel vertical supports placed under the roof.
• Bars & Caps: Distribute load between props.
• Chocks: Stacked supports used in depillaring and junctions.
• Hydraulic Props: Used in mechanized mines for quick setting.

2. Permanent Supports

• Steel Arches: Used in main roadways or long-term entries.
• Concrete Lining: Common in shafts and haulages.
• Brick or Masonry Supports: For stable and long-term roadways.

3. Roof Bolting

• Most modern and DGMS-recommended system.
• Bolts (1.2–2.4 m long) anchor the strata layers to prevent separation.
• Resin capsules used for immediate setting.
• DGMS requires testing of bolts for pull load and torque resistance.

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📜 CMR 2017 – Key Provisions (Reg. 99–106)

Regulation	Key Provision
99	Systematic support rule and roof plan approval
100	Support standards based on strata conditions
101	Use of tested materials only
102	Manager’s responsibility for support implementation
103	Testing of support systems regularly
104	Record of falls and remedial actions
105	Support plan display in working areas
106	Reporting to DGMS for any major roof fall

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🪓 DGMS Safety Requirements

• Support plan must be approved by DGMS and displayed in the mine office.
• Systematic support rule (SSR) should specify spacing, material, and installation method.
• Tell-tales or strata movement indicators must be installed.
• No person shall work under unsupported roof.
• Roof testing to be done before allowing men to work after blasting.
• Training of all officials and miners in roof control is mandatory.

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⚒️ Roof Bolting in Indian Mines

• Introduced in 1970s; now standard practice.
• DGMS encourages use of mechanized bolters.
• For thick seams, cable bolting and grouted anchors are used.
• Safety record shows significant reduction in FOG after bolting adoption.

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⚡ Common Roof Hazards

• Weak laminated strata (shales, fireclay).
• Excessive extraction leading to subsidence.
• Blasting vibration causing detachment.
• Poor ventilation (affects support integrity).
• Inadequate support spacing or material failure.

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🧠 Quick One-Liners

• Reg. 99–106 → Roof support system rules.
• Roof bolting → DGMS-approved method.
• Tell-tale → detects strata movement.
• SSR → Systematic Support Rule.
• No work under unsupported roof.
• Hydraulic props → used in mechanized depillaring.

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✍️ Descriptive Model Answer 

Q: Explain roof support systems and DGMS safety provisions for underground mines.
Answer:
Roof support ensures stability of mine workings. DGMS under CMR 2017 (Reg. 99–106) requires every mine to have an approved Systematic Support Rule (SSR) specifying the support plan.
Supports include props, bars, chocks, arches, and roof bolts. Roof bolting binds weak layers and minimizes fall risk.
Managers must maintain support records, test materials, and ensure no miner works under unsupported roof. DGMS enforces strict compliance to minimize FOG incidents.

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🎯 25 MCQs – Roof Support Systems & DGMS Rules 

Q1. The main purpose of roof support is to:
A. Increase production
B. Prevent roof collapse
C. Improve ventilation
D. Reduce blasting cost
E. Reduce dust
Answer: B.
Solution: Roof supports ensure roof stability and safety.

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Q2. Regulation 99 of CMR 2017 deals with:
A. Roof support systems
B. Ventilation
C. Haulage
D. Surveying
E. Fire precautions
Answer: A.
Solution: Reg. 99 specifies support system approval.

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Q3. The Systematic Support Rule (SSR) is approved by:
A. Manager
B. DGMS
C. Agent
D. Overman
E. Safety officer
Answer: B.
Solution: DGMS must approve SSR.

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Q4. Roof bolting primarily helps in:
A. Improving ventilation
B. Holding rock layers together
C. Reducing dust
D. Controlling gas
E. None
Answer: B.
Solution: Bolts anchor strata to prevent separation.

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Q5. The length of standard roof bolt is:
A. 0.5–1.0 m
B. 1.2–2.4 m
C. 3–5 m
D. 5–10 m
E. Variable
Answer: B.
Solution: 1.2–2.4 m bolts commonly used.

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Q6. Roof testing must be done:
A. Before blasting
B. After blasting
C. Before allowing men to work
D. At shift end
E. Monthly
Answer: C.
Solution: Roof must be checked after blasting.

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Q7. The safest roof support in laminated strata is:
A. Wooden props
B. Roof bolting
C. Chocks
D. Concrete lining
E. None
Answer: B.
Solution: Bolts prevent separation of weak layers.

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Q8. Tell-tales are used for:
A. Gas monitoring
B. Roof movement detection
C. Water level
D. Airflow
E. Vibration
Answer: B.
Solution: Tell-tales detect roof convergence.

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Q9. SSR should be:
A. Verbal instruction
B. Approved and displayed
C. Secret document
D. Only for depillaring
E. None
Answer: B.
Solution: Must be displayed at pithead.

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Q10. DGMS mandates which support for mechanized panels?
A. Hydraulic props
B. Wooden chocks
C. Sandbags
D. Timber caps
E. None
Answer: A.
Solution: Hydraulic props in mechanized mines. 

Q11. The most common cause of roof falls in underground mines is:
A. Excessive blasting
B. Inadequate support spacing
C. Ventilation stoppage
D. Gas leakage
E. Water seepage
Answer: B.
Solution: Poorly spaced or delayed supports are a leading cause of FOG (Fall of Ground).

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Q12. Regulation 104 of CMR 2017 mandates:
A. Record of ventilation
B. Reporting and recording of roof falls
C. Daily production record
D. Roof bolt length standardization
E. Dust sampling frequency
Answer: B.
Solution: Reg. 104 requires recording every roof fall and corrective action in a register.

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Q13. Roof bolting pull test is performed to:
A. Check resin quality
B. Test bolt anchorage strength
C. Verify bolt length
D. Ensure torque limit
E. Record mine temperature
Answer: B.
Solution: Pull test confirms anchorage of bolts in strata.

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Q14. Cable bolting is preferred in:
A. Shallow workings
B. Very thick seams
C. Opencast benches
D. Surface workshops
E. Non-coal mines only
Answer: B.
Solution: Cable bolts (up to 6 m long) stabilize thick seam roofs.

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Q15. DGMS recommends roof monitoring frequency as:
A. Weekly
B. Monthly
C. Each shift
D. Quarterly
E. Annually
Answer: C.
Solution: Roof must be checked every shift before entry.

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Q16. Chock supports are generally constructed with:
A. Cement blocks
B. Timber logs
C. Hydraulic jacks
D. Sandbags
E. Steel props
Answer: B.
Solution: Timber chocks are compact, strong, and easy to remove.

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Q17. The maximum spacing between roof bolts depends on:
A. Seam inclination
B. Strata condition
C. Lighting arrangement
D. Mine type
E. Airflow
Answer: B.
Solution: DGMS specifies spacing as per local strata stability.

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Q18. SSR (Systematic Support Rule) must be:
A. Drafted by the overman
B. Approved by DGMS
C. Optional for small mines
D. Verbal instruction
E. Displayed only during inspection
Answer: B.
Solution: DGMS approval ensures the SSR meets national safety norms.

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Q19. Reg. 105 of CMR 2017 states:
A. SSR must be displayed in mine office
B. Roof fall reports must be sealed
C. Bolts must be tested annually
D. Dust limits to be maintained
E. Water drainage to be ensured
Answer: A.
Solution: Display ensures all workers know the support plan.

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Q20. Strata control instrumentation includes:
A. Thermometer and barometer
B. Tell-tales and convergence indicators
C. Flow meter
D. Seismograph
E. Vibration counter
Answer: B.
Solution: These tools detect early roof movement signs.

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Q21. DGMS Tech Circular 02 of 2010 focuses on:
A. Ventilation standards
B. Roof & slope stability monitoring
C. Electrical safety
D. Explosives handling
E. Personnel management
Answer: B.
Solution: It provides guidelines for slope and roof stability.

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Q22. Who maintains the record of roof testing and support installation?
A. Sirdar
B. Overman
C. Manager
D. Agent
E. Surveyor
Answer: C.
Solution: As per Reg. 102, the manager ensures record maintenance.

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Q23. The main function of steel arches in roadways is to:
A. Improve ventilation
B. Support long-term entries
C. Reduce water seepage
D. Aid communication
E. Prevent gas layering
Answer: B.
Solution: Steel arches provide durable long-term roof support.

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Q24. Under DGMS guidelines, no person shall work under:
A. Low illumination
B. Unsupported roof
C. Noisy area
D. Wet ground
E. Low temperature
Answer: B.
Solution: Working under unsupported roof is strictly prohibited (CMR 102).

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Q25. The minimum training required for miners in roof safety includes:
A. Surface blasting course
B. Gas testing
C. Strata control and roof support training
D. Survey plotting
E. Timber measurement
Answer: C.
Solution: DGMS requires all miners to be trained in roof control for underground safety.

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                           🧩Conclusion

Roof support is the backbone of underground mine safety.
Adhering to CMR 2017 Reg. 99–106, systematic support rules, and DGMS-approved bolting systems drastically reduce fall-of-ground incidents.
A competent manager must ensure supervision, training, and testing — the foundation of a safe and productive mine. 

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