🔹 1. Introduction

Excavation performance determines how efficiently fragmented rock can be handled by:

• Shovels
  
• Loaders
  
• Draglines
  
• Dozers
  
• Rippers
  

Three essential parameters influence excavation:

1. Swell Factor
   
2. Excavatability
   
3. Work Index
   

Accurate estimation helps plan:

• Fleet size
  
• Bench design
  
• Blast requirement
  
• Production scheduling
  
• Cost estimation
  

🔹 2. Swell Factor (SF)

Swell Factor is the increase in volume of rock after it is fragmented (broken from in-situ condition).Swell Factor=Loose VolumeIn-situ Volume\text{Swell Factor} = \frac{\text{Loose Volume}}{\text{In-situ Volume}}Swell Factor=In-situ VolumeLoose Volume
2.1 Typical Swell Values

Material	Swell (%)
Soft soil	10–20%
Clay	20–40%
Sandstone	30–50%
Limestone	40–60%
Hard rock (blasted)	50–70%

2.2 Example Calculation

In-situ rock volume = 100 m³
Swell = 50%Loose volume:=100×(1+0.50)=150 m3= 100 \times (1 + 0.50) = 150 \, m^3=100×(1+0.50)=150m3
2.3 Importance of Swell Factor

• Determines truck body size
  
• Helps calculate dump volume
  
• Required for dragline stripping
  
• Influences blasting design
  

🔹 3. Excavatability

Excavatability indicates how easily material can be excavated or broken by:

• Shovel
  
• Dozer
  
• Ripper
  
• Loader
  

Depends on:

• Rock strength
  
• Fracturing
  
• Joint spacing
  
• Blasting quality
  
• Moisture
  

3.1 Excavatability Index (EI)

The index is based on:

• Uniaxial Compressive Strength (UCS)
  
• Rock Quality Designation (RQD)
  
• Joint spacing
  
• Hardness
  

Low EI → Easy to excavate
High EI → Hard excavation (requires blasting)
3.2 Classification

EI	Condition	Equipment
< 20	Easy	Dozer, loader
20–40	Moderate	Shovel
40–60	Hard	Shovel + blasting
> 60	Very Hard	Drill–blast required

🔹 4. Work Index (Bond’s Work Index)

Work Index (Wi) is the energy required to reduce rock from infinite size to 100 microns.Measured in:kWh per tonne\text{kWh per tonne}kWh per tonne
4.1 MeaningHigher Wi → harder rock → more energy needed to crush/excavate.
4.2 Typical Wi Values

Material	Wi (kWh/tonne)
Coal	6–8
Limestone	10–12
Basalt	15–17
Granite	20–22

🔹 5. Relationship Between Blasting & Excavation

Good blasting =
✔ Better fragmentation
✔ High fill factor
✔ Low shovel cycle time
✔ Less fuel consumption
✔ Higher productivityPoor blasting =
✘ Oversize boulders
✘ Low fill factor
✘ High digging resistance
✘ Low production

🔹 6. Diagram (Text Format)Swell Effect

In-situ Rock[██████████] = 1 m³
After Blasting[██ ██ ██ ███] = 1.5 m³ (50% swell)
Excavatability vs Fragmentation
Good blast → Small fragments → Easy digging (low EI)Poor blast → Boulders → Hard digging (high EI)
Work Index Relationship
High Wi → High energy → Hard excavationLow Wi → Low energy → Easy excavation

🔥  25 MCQs with Answers (DGMS Pattern)
1) Swell factor represents —

a) Rock hardness
b) Increase in volume after blasting
c) Density
d) Cycle time
e) None
Answer: b
2) Hard rock swell factor —

a) 2–5%
b) 10–20%
c) 50–70%
d) 90%
e) None
Answer: c
3) Loose volume is —

a) Less than in-situ
b) Greater than in-situ
c) Equal to in-situ
d) Zero
e) None
Answer: b
4) Excavatability depends on —

a) Joint spacing
b) Rock strength
c) Moisture
d) Blasting
e) All of these
Answer: e
5) High EI indicates —

a) Easy digging
b) Hard excavation
c) Soft soil
d) Wet conditions
e) None
Answer: b
6) Work Index measures —

a) Truck fuel
b) Energy needed to crush rock
c) Blasting cost
d) Rig penetration
e) None
Answer: b
7) Typical Wi of granite —

a) 5
b) 10
c) 20–22
d) 40
e) 60
Answer: c
8) Good blasting reduces —

a) Bench height
b) Excavation resistance
c) Ore density
d) Dump volume
e) None
Answer: b
9) Excavation performance helps in —

a) Drill bit selection
b) Ventilation
c) Fleet size planning
d) Roof bolting
e) None
Answer: c
10) Loose volume depends on —

a) Fill factor
b) Swell factor
c) Truck size
d) Road gradient
e) None
Answer: b
11) EI < 20 means —

a) Hard rock
b) Firm rock
c) Easy excavation
d) Very hard rock
e) None
Answer: c
12) Low Wi means rock is —

a) Hard
b) Soft
c) Metallic
d) Dense
e) None
Answer: b
13) Work Index unit —

a) m³/hr
b) kN
c) kWh/tonne
d) rpm
e) None
Answer: c
14) In-situ volume refers to —

a) Blasted condition
b) Loose condition
c) Natural solid condition
d) Dumped condition
e) None
Answer: c
15) High swell causes —

a) Less dump space
b) More dump volume required
c) High digging force
d) Lower payload
e) None
Answer: b
16) Excavation difficulty increases with —

a) High joint spacing
b) High UCS value
c) High moisture
d) Good blasting
e) None
Answer: b
17) EI > 60 means —

a) Easy digging
b) Blasting must be used
c) No drilling
d) High swell
e) None
Answer: b
18) Fragment size affects —

a) Groundwater
b) Shovel fill factor
c) Dump gradient
d) Pit slope
e) None
Answer: b
19) Swell factor of limestone —

a) 40–60%
b) 90%
c) 5%
d) 200%
e) None
Answer: a
20) Excavation depends on —

a) Rock mass rating
b) Weather
c) Truck capacity
d) Stemming
e) Rock properties
Answer: e
21) Poor blasting results in —

a) Faster digging
b) Oversized boulders
c) Easy loading
d) Less resistance
e) None
Answer: b
22) Dragline performance depends on —

a) Bench width
b) Swell factor
c) Powder factor
d) Truck size
e) None
Answer: b
23) High Wi means —

a) Weak rock
b) Hard rock
c) Soft soil
d) Loose muck
e) None
Answer: b
24) Blasting improves —

a) Road grade
b) Dust
c) Excavatability
d) Water seepage
e) None
Answer: c
25) Loose density is —

a) Higher than in-situ
b) Equal to in-situ
c) Lower than in-situ
d) Zero
e) None
Answer: c
                      🔚 Conclusion

Excavation performance is a key factor in surface mining productivity.
Understanding swelling, excavatability, and work index allows engineers to:

• Predict digging resistance
  
• Select suitable equipment
  
• Design optimal blasting patterns
  
• Improve cycle time
  
• Reduce cost per tonne
  

DGMS emphasizes proper excavation design for safe and efficient mining.

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