Design and Construction of Tunnels Quiz

Explanation
Polycentric-shaped tunnels have multiple centers, meaning they have more than one highest point or apex. This shape allows for better traffic movement because it provides enough flat bases for vehicles to navigate through the tunnel. The multiple centers also help distribute the weight and pressure evenly, making the tunnel more stable and structurally sound. Circular-shaped tunnels may not provide enough flat bases for traffic movement, while egg-shaped tunnels may not have multiple centers. Therefore, polycentric-shaped tunnels are the most suitable option for efficient traffic flow.

Explanation
According to the empirical formula, the thickness of the lining in mm is 82 times the diameter of the tunnel.

Explanation
The statement is true because both the wagon drill and churn drill are types of percussion drills. Percussion drills work by repeatedly striking the rock surface with a chisel-like bit, creating a hole. The wagon drill is a portable drilling rig mounted on wheels, commonly used in mining and construction. The churn drill, also known as a cable tool drill, uses a heavy bit attached to a cable that is repeatedly dropped and raised to break the rock. Both drills use percussive action to penetrate the ground, making the statement true.

Explanation
For tunnels greater than 3 meters in diameter, ribs are used to strengthen and stiffen the liner plate. Ribs are structural elements that are installed along the circumference of the tunnel to provide additional support and prevent deformation or collapse. These ribs distribute the load evenly and help to maintain the stability and integrity of the tunnel structure.

Explanation
A cutting edge is a component of a shield used for tunneling. It is a sharp edge or blade that is attached to the front of the shield, allowing it to cut through the soil or rock as it moves forward. This helps to create a path for the shield to advance and makes the tunneling process more efficient. A cutting edge is an essential part of the shield's design and plays a crucial role in the excavation of tunnels.

Explanation
The statement is false because the shot drill is not a type of percussion drill. A shot drill is actually a type of rotary drill that is used for drilling holes in hard materials such as concrete or rock. It uses a rotating motion combined with a hammering action to break through the tough surface. On the other hand, a percussion drill uses only a hammering action to drill into materials. Therefore, the shot drill and the percussion drill are two different types of drills.

Explanation
Egg-shaped tunnels are suitable as sewer tunnels to carry sewage water because their design allows for efficient flow of the sewage. The elongated shape of the tunnel helps to maintain a self-cleansing velocity, preventing the accumulation of solids and reducing the risk of blockages. The shape also provides better hydraulic performance, minimizing the risk of surges and reducing the energy required for pumping. Additionally, the egg-shaped design allows for easier maintenance and inspection of the tunnel.

Explanation
The "Cut and Cover" method of construction is useful when the track is at a deeper level in the construction of Metro Railways. This method involves digging a trench, constructing the track, and then covering it back up. It is an effective technique for building underground infrastructure, especially when the depth of the track is significant. Therefore, the statement is true.

Explanation
A horse shoe type tunnel is a combined shape of arches as well as a circular tunnel. The shape of the tunnel resembles a horseshoe, with a curved top and straight sides. This shape provides structural stability and allows for efficient distribution of loads, making it suitable for various tunneling projects.

Explanation
Segmental tunnels are good for traffic tunnels. They are known as sections having an arched roof and straight sides. These types of tunnels are generally suitable for subway or navigation tunnels.