2. Definition & necessity
Underground passage which are constructed
without disturbing the ground surface
• route to be connected by shorter distance
• Conveying water for power generation
• To avoid acquisition of valuble land
• Protection againt landslide, snow fall
• Coneveying water,oil,gas
3. Advantages
• The connect terminal station by short route
• Less route length result in less transportation
cost
• They carry railway, road and water, oil, gas
• Avoiding holding up of traffic for long time
• To avoid acquisition of valuble land
• Protection againt landslide, snow fall
4. Disadvantages
• Require skilled labour & supervision
• Require Special equipment
• Costly in construction
• Require more time
• May cause suffocation if ventilation not
provided properly
5. Classification
According to purpose
i) Traffic tunnel
1. Railway
2. Highway
3. Navigation
4. Subway
5. Pedestrain
ii)Conveyance tunnel
1. Water supply
2. Hydropower
3. Sewage
4. Tunnel for industrial use
According to type of material
1. In hard rock
2. In soft rock
3. In quick sand
4. Uder river bed
According to position of alignment
1. Base tunnel
2. Spiral tunnel
3. Slope
7. Tunnel surveying
Involve the following operation
1. Location center line on the ground
2. Construction of shaft over center line
3. Transferring the center line inside the tunnel
8. Shaft
• When the length of tunnel is small, it can be
constructed by excavation
• The vertical opening along the alignment
9. Purpose of shaft
• To start excavation from both side
• To provide adequate natural ventilation
• To remove excavated material
• To provide passage for pumping out water
• To provide passage for construction tool,
machinery
• To transfer the center line inside the tunnel
10. Construction of shaft
• Drilling & blasting
• Mucking
• Timbering
• Pumping
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