🔹 1. Introduction

Traditional rock blasting uses high explosives, which create noise, vibration, and flyrock.
Non-detonating rock breaking tools provide a safe and controlled alternative for rock fragmentation — especially in populated or vibration-sensitive zones like tunnels, shafts, and urban mines.These tools operate without chemical detonation — instead, they use gas expansion, hydraulic pressure, or chemical reaction to break the rock silently and safely.

🔹 2. Purpose of Non-Detonating Tools

• To reduce vibration, flyrock, and noise in sensitive areas.
  
• To provide controlled splitting in confined mines and structures.
  
• To replace explosives where DGMS regulations restrict use.
  
• To ensure maximum safety for workers and nearby structures.
  

🔹 3. Types of Non-Detonating Rock Breaking Tools

Type	Principle	Description
Hydraulic Splitter	Hydraulic pressure	Uses pistons to generate 200–400 tons of pressure
Gas Expansion Cartridge	Combustion of propellant	Produces controlled pressure wave in borehole
Expanding Grout (Chemical Agent)	Chemical hydration	Produces slow expansive force to crack rock
Cartridge-Type Gas Generator	Thermal gas expansion	Used in civil demolition and tunneling

🔹 4. Working Principle

1. Drill holes (32–50 mm diameter, 0.5–1 m deep).
   
2. Insert the non-detonating cartridge or expansion pack.
   
3. The system releases gas or pressure gradually.
   
4. Internal stress exceeds rock tensile strength → cracks propagate.
   
5. Rock breaks into manageable blocks silently.
   

🔹 5. Advantages

• No vibration or flyrock
  
• Silent operation – ideal for urban or restricted zones
  
• No licensing for explosives required
  
• Environment-friendly (no toxic gases)
  
• Precise and controlled breaking
  

🔹 6. Limitations

• Slower process than traditional blasting
  
• Limited to small-scale or controlled works
  
• Requires uniform borehole pattern and correct pressure
• 🪨 Non-Detonating Rock Breaking Tools — 25 MCQs (5 options) + Solutions
• 1. Non-detonating rock breaking tools are primarily used when —
• a) High-speed fragmentation is essential
  b) Explosives are prohibited or vibration must be minimised
  c) Large-scale open-pit blasting is required
  d) Deep seismic energy injection is needed
  e) Maximum flyrock is acceptable
  Answer: b) Explosives are prohibited or vibration must be minimised
  Solution: These tools are chosen where vibration, flyrock, noise or explosive licensing are problems.
• 2. Which of the following is a hydraulic non-detonating tool?
• a) PETN cord
  b) Hydraulic splitter
  c) Expanding grout
  d) Gas pressure cartridge
  e) ANFO column
  Answer: b) Hydraulic splitter
  Solution: Hydraulic splitters use hydraulic cylinders/pistons to exert very high splitting force.
• 3. Expanding grout (chemical splitter) generates rock-breaking force by —
• a) Rapid detonation
  b) Slow chemical expansion (hydration)
  c) Hydraulic fluid pressure
  d) Compressed air release
  e) Thermal melting
  Answer: b) Slow chemical expansion (hydration)
  Solution: Grout expands slowly as it hydrates, building stress until the rock cracks.
• 4. Typical working pressure range for a commercial hydraulic splitter is about —
• a) 20–40 tons
  b) 200–400 tons
  c) 1–5 tons
  d) 1000–2000 tons
  e) 5–10 tons
  Answer: b) 200–400 tons
  Solution: Heavy hydraulic splitters commonly deliver several hundred tons of splitting force.
• 5. Gas expansion cartridges produce pressure inside a borehole by —
• a) Hydration of cement
  b) Combustion/rapid gas generation from a propellant
  c) Mechanical wedge action
  d) Electric heating
  e) Hydraulic actuation
  Answer: b) Combustion/rapid gas generation from a propellant
  Solution: A propellant generates gases that pressurize the borehole and split the rock.
• 6. Expanding grout is most valued for applications requiring —
• a) Immediate rock fragmentation in seconds
  b) Silent, low-vibration splitting over hours
  c) High blast energy for large blocks
  d) Airbone fragmentation for tunnelling
  e) High temperature cutting
  Answer: b) Silent, low-vibration splitting over hours
  Solution: Grout acts slowly (hours), producing near-silent splitting with minimal vibration.
• 7. Which borehole diameter is typically suitable for expanding grout or cartridge systems?
• a) 5–10 mm
  b) 32–50 mm
  c) 150–200 mm
  d) 250–300 mm
  e) >400 mm
  Answer: b) 32–50 mm
  Solution: Small to medium bores (≈32–50 mm) are commonly used for grout and gas cartridges.
• 8. A key limitation of non-detonating methods compared with conventional blasting is —
• a) Higher vibration levels
  b) Slower cycle time and lower productivity for large rock volumes
  c) Uncontrolled flyrock
  d) Requirement for detonators
  e) Need for heavy blast mats
  Answer: b) Slower cycle time and lower productivity for large rock volumes
  Solution: These methods are safer but slower, making them less suitable for high-volume blasting.
• 9. Which method gives the quietest operation?
• a) ANFO blasting
  b) Hydraulic splitter
  c) Tube-delayed electric blasting caps
  d) PETN detonating cord
  e) Large-calibre artillery shots
  Answer: b) Hydraulic splitter
  Solution: Hydraulic splitters generate negligible noise compared with explosive techniques.
• 10. Typical setting / crack development time for expanding grout is about —
• a) A few seconds
  b) 5–8 minutes
  c) 5–8 hours
  d) 24–48 hours
  e) Several weeks
  Answer: c) 5–8 hours
  Solution: Grout expands slowly; practical crack formation is commonly in the order of hours.
• 11. Non-detonating tools are particularly useful in —
• a) Remote open-pit blasting with heavy trucks
  b) Urban demolition and tunnel face preparation
  c) Offshore underwater bulk detonation
  d) Large quarry fragmentation for instant crushing
  e) High-explosive military applications
  Answer: b) Urban demolition and tunnel face preparation
  Solution: Low vibration and noise make them ideal for sensitive or confined environments.
• 12. Which of these is NOT an advantage of non-detonating methods?
• a) No requirement for explosive magazine licensing (in many jurisdictions)
  b) Minimal flyrock and vibration
  c) Instantaneous high-energy fragmentation for massive volumes
  d) Safer around sensitive structures
  e) Reduced environmental disturbance
  Answer: c) Instantaneous high-energy fragmentation for massive volumes
  Solution: Rapid, high-energy fragmentation is a strength of explosives, not of non-detonating methods.
• 13. Gas cartridges can reach local peak pressures on the order of —
• a) ~1 bar
  b) ~10 bar
  c) ~100–1000 bar (depending on design)
  d) ~0.1 bar
  e) Atmospheric pressure only
  Answer: c) ~100–1000 bar (depending on design)
  Solution: Cartridge systems generate very high pressures within the borehole sufficient to fracture rock.
• 14. Which safety precaution is most important when using expanding grout?
• a) Immediate evacuation due to explosion risk
  b) Avoid breathing dust and prevent contact with skin/eyes during mixing/handling
  c) Keep grout at high temperatures to speed action
  d) Use open flame to accelerate hydration
  e) Use electric detonators to initiate grout
  Answer: b) Avoid breathing dust and prevent contact with skin/eyes during mixing/handling
  Solution: Chemical agents (e.g., quicklime mixes) can be caustic; PPE and handling care are required.
• 15. For hydraulic splitters, the action mechanism that splits rock is —
• a) Rapid gas expansion inside hole
  b) Piston-driven wedge or spreading force in the borehole
  c) Chemical reaction producing heat
  d) Electromagnetic pulse
  e) Sonic resonance
  Answer: b) Piston-driven wedge or spreading force in the borehole
  Solution: Hydraulic pistons push wedges or expand a shaft to exert split forces against borehole walls.
• 16. The correct sequence for a grout splitting operation is generally —
• a) Drill boreholes → insert grout → pour water → leave to expand → break rock
  b) Mix grout with explosives → insert → detonate
  c) Drill very large holes → ram in grout → immediate break
  d) Excavate first → pour grout on surface
  e) None of above
  Answer: a) Drill boreholes → insert grout → pour water → leave to expand → break rock
  Solution: Grout requires drilling, filling, water activation (if needed), then time to expand and crack rock.
• 17. Which monitoring parameter is most useful to verify grout or cartridge action before approach?
• a) Visual crack propagation from a safe distance
  b) Immediate loud bang (expected)
  c) Electronic seismic spikes > 1000 units
  d) Smell of gas as confirmation
  e) Color change of surrounding rock
  Answer: a) Visual crack propagation from a safe distance
  Solution: Operators watch for surface cracks or other indicators from a safe distance; no loud bang is expected.
• 18. Non-detonating methods are commonly classified by DGMS as —
• a) Explosive charges
  b) Controlled mechanical/chemical rock-breaking techniques
  c) Illegal rock-breaking methods
  d) Military ordnance
  e) Unregulated demolition devices
  Answer: b) Controlled mechanical/chemical rock-breaking techniques
  Solution: DGMS treats them as controlled non-explosive rock-breaking methods with safety regimes.
• 19. A practical advantage of cartridge-type gas tools vs grout is —
• a) Much slower action time
  b) Immediate high pressure and faster cracking (minutes)
  c) No need for boreholes
  d) No PPE required
  e) Unlimited repeat cycles without replacement
  Answer: b) Immediate high pressure and faster cracking (minutes)
  Solution: Gas cartridges act faster than grout, often producing fractures within minutes.
• 20. Common borehole spacing for grout splitting to produce a controlled split depends on rock tensile strength and hole depth; which is a reasonable starting pattern in hard rock?
• a) 0.05 m spacing
  b) 0.5–1.0 m spacing
  c) 5–10 m spacing
  d) 10–20 m spacing
  e) No standard spacing required
  Answer: b) 0.5–1.0 m spacing
  Solution: Typical spacing of half-to-one metre is used for controlled splitting, adjusted for rock properties.
• 21. The noise level of non-detonating methods is typically —
• a) >120 dB (very loud)
  b) ~100–110 dB (loud)
  c) <85 dB (relatively quiet)
  d) Indistinguishable from a blast
  e) Silence is impossible to achieve
  Answer: c) <85 dB (relatively quiet)
  Solution: Non-detonating techniques are much quieter than conventional blasting; often below ~85 dB.
• 22. Which is an environmental benefit of non-detonating rock breaking?
• a) Increased ground vibration and structural damage
  b) Reduced airborne dust compared with open blasting (when properly controlled)
  c) Greater noxious gas emissions than blasting
  d) Higher flyrock production
  e) Permanent groundwater contamination always occurs
  Answer: b) Reduced airborne dust compared with open blasting (when properly controlled)
  Solution: With correct procedures, these methods can reduce dust, vibration and flyrock impacts.
• 23. Which of the following is a correct limitation for expanding grout?
• a) It works instantly (seconds) in all rocks
  b) It may be ineffective in single very tight, unfractured rock without pre-drilling adequate pattern
  c) It requires shaped charges to function
  d) It replaces explosives for all bulk mining needs
  e) It introduces explosives into the borehole
  Answer: b) It may be ineffective in single very tight, unfractured rock without pre-drilling adequate pattern
  Solution: Grout needs appropriate hole patterns and preconditions; very massive unfractured rock can be challenging.
• 24. Best PPE for operators handling non-detonating cartridges/grouts includes —
• a) No PPE required — safe by default
  b) Helmet, eye protection, gloves, dust mask/respirator and protective clothing
  c) Only a hard hat is needed
  d) Full blast suit and respirator for all tasks
  e) Underwater breathing apparatus
  Answer: b) Helmet, eye protection, gloves, dust mask/respirator and protective clothing
  Solution: Standard PPE for handling chemicals, dust and mechanical tools is necessary.
• 25. After a successful non-detonating split, the operator should first —
• a) Immediately stand above the broken face to inspect closely
  b) Wait the recommended safe interval, approach from a safe route, verify complete fracture and remove debris safely
  c) Ignore safety and begin heavy mobilisation of equipment
  d) Light a controlled fire to clear rubble
  e) Assume the area is permanently unstable and abandon forever
  Answer: b) Wait the recommended safe interval, approach from a safe route, verify complete fracture and remove debris safely
  Solution: Approach only after confirming the work from a safe vantage and following site safety protocols.
•                                         🔚 8. Conclusion
• Non-detonating rock breaking tools are a breakthrough in modern mining and civil engineering.
  They eliminate the risks of vibration and flyrock while ensuring efficient fragmentation in sensitive zones. DGMS recognizes them as a safe, controlled alternative to conventional blasting.
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