Introduction

🏗️ Detailed Notes

Definition:
A box cut is the first excavation made for opening a surface or underground mine. It appears like a rectangular open box with an inclined floor and three walls.

Objective of Box Cut:

• To reach the coal seam or ore body.
• To provide smooth entry for equipment.
• To create space for working benches.

Types of Box Cut:

1. Internal Box Cut:
• Located fully or partly within the mineralized zone.
• Applicable to all types of deposits.
• Usually oblique to strike and dip to avoid steep turns.
2. External Box Cut:
• Located outside the mineralized zone.
• Used for shallow, gently dipping beds.
• Usually made on the rise side for drainage and haul road ease.

⚡ Quick One-Liners

• First excavation = Box Cut.
• Shape: rectangular, open from top.
• Two types → Internal & External.
• Internal box cut lies on ore zone; external lies outside.
• Designed for smooth haul road entry.
• CMR 2017 Reg. 101 & 105 apply to slope and road safety.

✍️ Descriptive Model Answer

Q: What is a box cut and explain its types with examples.

Answer:
A box cut is the initial excavation made to reach a mineral deposit in an opencast mine. It looks like an open box with inclined floor and walls on three sides.
Types:

• Internal Box Cut: within the mineralized zone, common for deep or steep deposits.
• External Box Cut: outside the ore zone, used for shallow beds to ensure drainage and easy entry.
  Example: Most coal mines in India start with an external box cut on the rise side.

🎯 25 MCQs – Box Cut Basics 

Q1. The first excavation made to open an opencast mine is called:
A. Ramp
B. Box Cut
C. Trench
D. Pit Bottom
E. Bench
Answer: B.
Solution: Box cut is the first excavation step for mine development.

Q2. The shape of a box cut resembles:
A. Circle
B. Ellipse
C. Open rectangular box
D. Triangle
E. Cube
Answer: C.
Solution: Box cut has an open top and three-sided walls.

Q3. Primary purpose of a box cut is:
A. Blasting preparation
B. Drainage control
C. To reach coal seam and start benching
D. Dump management
E. Ventilation planning
Answer: C.
Solution: Box cut helps reach the mineral seam and prepare benches.

Q4. Internal box cut is located:
A. Outside mineral zone
B. Inside or partly on ore zone
C. Parallel to dip direction
D. On the rise side
E. On overburden dump
Answer: B.
Solution: Internal box cut lies on mineralized area.

Q5. External box cut is preferred for:
A. Steep seams
B. Shallow and flat deposits
C. Deep vertical seams
D. Underground mines
E. None
Answer: B.
Solution: External box cuts are made outside mineralized zone for shallow beds.

Q6. The orientation of a box cut in an opencast mine should preferably be:
A. Against the dip of the seam
B. Along the dip of the seam
C. Perpendicular to the strike
D. Against the strike
E. Random orientation
Answer: B.
Solution: Box cut is generally made along the dip to facilitate drainage and haulage alignment.

Q7. The minimum recommended overall slope angle for soft overburden is:
A. 70°
B. 60°
C. 55°
D. 45°
E. 35°
Answer: D.
Solution: Soft OB requires gentle slopes (around 45°) to prevent slips and slides.

Q8. The drainage gradient on the haul road in a box cut should be approximately:
A. 1 in 10
B. 1 in 25
C. 1 in 50
D. 1 in 100
E. 1 in 200
Answer: D.
Solution: A gentle slope of 1 in 100 ensures effective drainage without erosion.

Q9. As per DGMS guidelines, water collected in box cut areas should be:
A. Pumped directly to the surface
B. Allowed to stagnate
C. Treated and reused or discharged as per EMP
D. Mixed with overburden
E. Ignored if less than 1 m³/hr
Answer: C.
Solution: DGMS and MOEF rules mandate treatment before discharge to maintain environmental compliance.

Q10. Which of the following DGMS Circulars provides guidance on slope and haul road stability?
A. Tech Circular 02 of 2010
B. General Circular 01 of 2023
C. Exam Circular 01 of 2021
D. Circular 07 of 2019
E. Tech Circular 04 of 2018
Answer: A.
Solution: DGMS Tech Circular 02/2010 specifies slope, bench, and road safety in opencast mines.

Q11. The parapet wall at the edge of a box cut should be built with:
A. Loose overburden
B. Compacted material or RCC
C. Dumped spoil
D. Plastic barrels
E. Timber posts
Answer: B.
Solution: Loose OB is unstable; parapets must be made of compacted or reinforced material.

Q12. The ideal haul road width for one-way traffic in box cut design:
A. Equal to dumper width
B. Dumper width + 3 m
C. Dumper width + 5 m
D. 2 × dumper width
E. Fixed 10 m
Answer: C.
Solution: As per CMR 2017 Regulation 101(3), one-way road = dumper width + 5 m.

Q13. The haul road gradient in box cut areas should not exceed:
A. 1 in 10
B. 1 in 12
C. 1 in 16
D. 1 in 20
E. 1 in 25
Answer: C.
Solution: CMR 2017 prescribes maximum haul road gradient = 1 in 16.

Q14. The ramp gradient for crawler-mounted equipment in a box cut is:
A. 1 in 5
B. 1 in 8
C. 1 in 10
D. 1 in 12
E. 1 in 16
Answer: C.
Solution: DGMS allows 1 in 10 for short ramps used by crawler-type machinery.

Q15. Factor of Safety (FOS) for temporary slopes in OB benches is:
A. 1.0
B. 1.1
C. 1.2
D. 1.3
E. 1.5
Answer: C.
Solution: Temporary slopes must maintain FOS ≥ 1.2 for short-term stability.

Q16. The Standing Safety Report (SSR) must include which of the following?
A. Mining engineer’s resume
B. Slope design, drainage & monitoring plan
C. Annual production report
D. Equipment purchase data
E. Blast record log
Answer: B.
Solution: SSR is a safety document including slope, haul road, drainage & monitoring details.

Q17. The minimum base width of a parapet wall must be:
A. 1.5 m
B. 2.0 m
C. 2.5 m
D. 3.0 m
E. 4.0 m
Answer: C.
Solution: As per CMR 2017, base width must be at least 2.5 m for stability.

Q18. The typical angle of repose for OB material in box cuts is:
A. 25°–30°
B. 30°–35°
C. 35°–40°
D. 40°–45°
E. 50°–55°
Answer: B.
Solution: Loose OB typically has a repose angle between 30°–35°.

Q19. Which DGMS form is used for daily inspection of box cut slopes?
A. Form I
B. Form IV
C. Form X
D. Form A
E. Form 2B
Answer: B.
Solution: Form IV records daily inspection of workings and slopes under CMR 2017.

Q20. The purpose of providing drainage sumps in box cut is:
A. Water storage
B. Water treatment
C. Dewatering and sediment removal
D. Equipment washing
E. None of the above
Answer: C.
Solution: Sumps collect water and sediment before pumping out safely.

Q21. Maximum ramp length per stretch allowed in box cut:
A. 25 m
B. 50 m
C. 75 m
D. 100 m
E. No limit
Answer: B.
Solution: As per DGMS circulars, ramp length ≤ 50 m to control stability and braking risk.

Q22. Geotechnical parameters like UCS, RQD, and cohesion are used for:
A. Ventilation design
B. Slope stability analysis
C. Pump selection
D. Explosive design
E. Surveying
Answer: B.
Solution: Geotechnical testing provides input for slope stability and design.

Q23. The parapet wall height in box cut areas must be:
A. 1 m
B. Equal to half tyre diameter
C. Equal to tyre diameter of largest dumper
D. Fixed 2 m
E. Manager’s discretion
Answer: C.
Solution: Ensures dumpers cannot fall over edge.

Q24. Box cut slope monitoring must be done:
A. Weekly
B. Fortnightly
C. Daily or continuous
D. Monthly
E. Annually
Answer: C.
Solution: Continuous monitoring is essential for slope safety (DGMS standard).

Q25. The primary purpose of box cut design approval from DGMS is:
A. Record keeping
B. Reducing production delay
C. Ensuring mine stability and worker safety
D. Legal compliance only
E. Cost optimization
Answer: C.
Solution: DGMS approval ensures design is safe, stable, and regulatory compliant.

                                            ✅ Conclusion

The box cut forms the foundation of an opencast mine’s life cycle. Proper design, drainage, and slope management — as per CMR 2017 (Reg. 101, 104, 127) and DGMS Circular 02/2010 — ensure long-term operational safety and prevent slope failures.
Adherence to parapet dimensions, gradient control, and SSR documentation is mandatory for every mine manager aiming to meet DGMS compliance.

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