Introduction 

The box cut is the first excavation in an opencast mine, providing entry for heavy earth-moving machinery (HEMM).
A well-designed box cut ensures:

• Safe initial access,
• Efficient haulage,
• Proper drainage, and
• Long-term slope stability.

The Directorate General of Mines Safety (DGMS) provides detailed design and construction parameters through CMR 2017 and Technical Circular 02 of 2010 to minimize risks.

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⚙️ 1. Design Parameters a) Slope Angle

• Determined by geotechnical investigation (core recovery, RQD, UCS tests).
• Recommended slope angles:
• Hard rock: 65°–70°
• Soft strata: 45°–55°
• Alluvial soil: 35°–40°
• Factor of safety (FOS): ≥ 1.3 for permanent slopes (DGMS standard).

b) Bench Height and Width

• Bench height = based on equipment (e.g., 10–15 m for 100T dumpers).
• Bench width ≥ 3 × height for safe berm construction.
• Benches must have proper drainage channels.

c) Gradient of Haul Roads

• Maximum gradient: 1 in 16.
• Ramp gradient (for crawler equipment): 1 in 10, max length 50 m.
• Gentle gradient ensures safety and easy braking.

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💧 2. Drainage & Water Management

• Floor slope: 1 in 100 toward sump.
• Peripheral drains collect surface runoff.
• Sumps should be designed for max rainfall intensity + water inflow from strata.
• Pump capacity must handle 1.5× expected inflow rate.
• DGMS Circular 01/2012 emphasizes mine water management in box cut areas.

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🧱 3. Parapet & Edge Protection

• Parapet wall:
• Top width: ≥ 1.0 m
• Bottom width: ≥ 2.5 m
• Height: ≥ tyre diameter of largest dumper.
• Constructed with compacted OB or RCC.
• Dumping of loose OB as parapet is not permitted.

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📋 4. SSR (Standing Safety Report) – Key Design Contents

1. Cross-section showing box cut layout.
2. Slope design calculations & FOS values.
3. Drainage and sump design data.
4. Haul road width & gradient.
5. Monitoring plan for slope movement.
6. Geotechnical report references.

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🧠 5. DGMS Compliance

• All box cut designs must be approved by Regional Inspector (DGMS).
• Daily inspections (Form IV) mandatory.
• Stability monitoring: inclinometers, extensometers, piezometers.
• Deviation from approved design requires fresh authorization.

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⚡ Quick One-Liners (Revision Notes)

• FOS ≥ 1.3 (permanent slope).
• Slope angle varies with rock type (35°–70°).
• Road gradient ≤ 1:16.
• Ramp gradient ≤ 1:10, length ≤ 50 m.
• Parapet wall height ≥ dumper tyre diameter.
• Floor slope 1:100 toward sump.
• SSR mandatory for every opencast mine.
• DGMS Circular 02/2010 governs slope & haul road.
• Regular monitoring using instruments.
• Form IV → daily inspection report.

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🧾 25 DGMS-Based MCQs – Box Cut Design Parameters

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Q1. The maximum gradient for haul roads in box cut areas is:
A. 1 in 8
B. 1 in 10
C. 1 in 12
D. 1 in 16
E. 1 in 20
Answer: D.
Solution: As per CMR 2017 Reg. 101, road gradient ≤ 1 in 16.

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Q2. Minimum Factor of Safety for permanent slopes in box cut design:
A. 1.0
B. 1.1
C. 1.2
D. 1.3
E. 1.5
Answer: D.
Solution: DGMS recommends FOS ≥ 1.3 for long-term slope stability.

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Q3. Parapet wall height must be:
A. 1 m
B. Equal to dumper tyre diameter
C. 2.5 m fixed
D. Manager’s discretion
E. None
Answer: B.
Solution: Regulation requires height = largest dumper tyre diameter.

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Q4. Drainage slope at floor level should be:
A. 1 in 10
B. 1 in 25
C. 1 in 50
D. 1 in 100
E. 1 in 200
Answer: D.
Solution: Gentle slope ensures proper drainage.

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Q5. Bench width in box cut must be at least:
A. Equal to bench height
B. 2 × bench height
C. 3 × bench height
D. 4 × bench height
E. None
Answer: C.
Solution: Provides adequate berm and access for vehicles.

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Q6. Recommended slope angle for hard rock strata:
A. 30°
B. 40°
C. 50°
D. 65°–70°
E. 75°
Answer: D.
Solution: High-angle stable slopes are safe for hard rock.

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Q7. Ramp gradient for crawler-mounted machines:
A. 1 in 8
B. 1 in 10
C. 1 in 12
D. 1 in 14
E. 1 in 16
Answer: B.
Solution: Crawler ramps must not exceed 1 in 10 gradient.

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Q8. Pump capacity in box cut drainage must be at least:
A. Equal to inflow
B. 1.25× inflow
C. 1.5× inflow
D. 2× inflow
E. Variable
Answer: C.
Solution: DGMS recommends 1.5× design inflow for safe dewatering.

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Q9. Standing Safety Report (SSR) must be updated:
A. Once every 5 years
B. Every 2 years or after change in design
C. Monthly
D. Weekly
E. Daily
Answer: B.
Solution: SSR must be revised after any significant layout change.

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Q10. Instrument used for slope movement detection:
A. Barometer
B. Inclinometer
C. Anemometer
D. Hygrometer
E. None
Answer: B.
Solution: Inclinometers detect angular displacement of slopes.

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Q11. DGMS approval for box cut design is taken from:
A. District Magistrate
B. Regional Inspector
C. Chief Engineer
D. Ministry of Mines
E. None
Answer: B.
Solution: Regional Inspector approves SSR and design plan.

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Q12. Haul road top width (one-way) = dumper width + ____ m.
A. 3 m
B. 4 m
C. 5 m
D. 6 m
E. 8 m
Answer: C.
Solution: As per CMR 2017 Reg. 101(3).

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Q13. DGMS Technical Circular 02/2010 covers:
A. Dust Control
B. Slope Stability & Haul Road Design
C. Ventilation
D. Fire Control
E. Explosives
Answer: B.
Solution: Focused on opencast slope and road design.

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Q14. Parapet bottom width must be at least:
A. 1.5 m
B. 2.0 m
C. 2.5 m
D. 3.0 m
E. 3.5 m
Answer: C.
Solution: Minimum base width 2.5 m ensures structural stability.

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Q15. Factor considered in slope design:
A. Soil cohesion
B. Rainfall
C. Equipment load
D. All of the above
E. None
Answer: D.
Solution: Geotechnical + environmental + operational factors determine slope.

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Q16. Bench height for 100T dumper mine:
A. 5 m
B. 10–15 m
C. 20 m
D. 25 m
E. 30 m
Answer: B.
Solution: Optimum height for equipment reach and stability.

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Q17. SSR includes:
A. Production report
B. Mine manager’s resume
C. Slope design, drainage, haul road details
D. Equipment list only
E. None
Answer: C.
Solution: SSR documents all safety-related design parameters.

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Q18. Floor level should slope towards:
A. Ramp
B. Sump
C. Haul road
D. Office
E. Workshop
Answer: B.
Solution: Ensures proper drainage.

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Q19. Slope stability monitoring frequency:
A. Weekly
B. Fortnightly
C. Monthly
D. Continuous or daily
E. Quarterly
Answer: D.
Solution: Continuous monitoring required for critical slopes.

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Q20. Parapet construction material must be:
A. Loose OB
B. Compacted OB or RCC
C. Timber
D. Plastic drums
E. Scrap
Answer: B.
Solution: Must be stable and rigid.

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Q21. SSR prepared by:
A. Surveyor
B. Geotechnical engineer
C. Mining engineer (manager)
D. DGMS officer
E. Overman
Answer: C.
Solution: Manager ensures compliance with DGMS standards.

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Q22. Typical bench slope for soft strata:
A. 30°
B. 40°
C. 45°–55°
D. 60°
E. 70°
Answer: C.
Solution: Soft strata need gentle slope for stability.

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Q23. Box cut layout is approved:
A. After mine plan approval
B. Before excavation starts
C. During operation
D. After closure
E. Anytime
Answer: B.
Solution: Layout approved before first excavation.

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Q24. Daily slope inspection record kept in:
A. Form IV
B. Form X
C. Form 2A
D. Form B
E. Form 7
Answer: A.
Solution: Mandatory under CMR 2017.

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Q25. The primary purpose of box cut is:
A. Drainage
B. Initial access for mining
C. Storage
D. Backfilling
E. Exploration
Answer: B.
Solution: Box cut opens the first entry for HEMM into deposit.

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                        ✅ Conclusion

Proper box cut design minimizes slope failures, enhances safety, and ensures legal compliance.
A DGMS-approved design following CMR 2017 and Technical Circulars protects both personnel and production.

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