Other Industrial Engineering & Manufacturing Subjects
Tunnelling
For full face method, the excavation to be done is generally divided into
Explanation:
In the full face method of tunneling, the entire tunnel face is excavated in a single continuous operation to maintain stability and efficiency. This process is systematically divided into four distinct sections, typically arranged in a cross pattern, to ensure balanced removal of earth. This four-section approach allows for uniform support installation and minimizes the risk of face collapse during the digging phase.
Railway tunnels, are generally
Explanation:
Railway tunnels are generally designed with a circular or horseshoe cross-section to maximize structural strength against the immense lateral pressure of surrounding earth and rock. This shape distributes stress evenly around the perimeter, preventing collapse and ensuring long-term stability without requiring excessive reinforcement. While rectangular shapes are sometimes used for specific urban contexts, the circular form remains the standard engineering solution for deep underground passages. Consequently, the term "polycentric," referring to a multi-centered or complex structural arrangement, accurately describes this robust, load-bearing geometry in this specific context.
To attain the required shape of the tunnel section, we use:
Explanation:
Trimmers are specialized tools designed to precisely remove small amounts of material from the edges of a workpiece. In tunnel construction, they are essential for refining the rough outline into the exact required cross-sectional shape. By allowing for fine adjustments and smooth finishing, they ensure the tunnel dimensions match the engineering specifications perfectly. This process is critical for maintaining structural integrity and proper fit within the surrounding geological environment.
The tunnels, the artificial underground passages are constructed for:
Explanation:
Artificial underground tunnels are versatile structures designed to accommodate various essential infrastructure needs within urban environments. They serve as critical conduits for sewerage systems to manage wastewater, act as protective channels for water supply pipelines to ensure safe delivery, and function as subterranean highways for efficient traffic flow. Since these passages are fundamentally constructed to support all these distinct yet vital functions simultaneously, the comprehensive option accurately reflects their broad utility in modern civil engineering and city planning.
Which one of the following methods is generally adopted for tunnelling in firm ground
Explanation:
The full face method is the standard technique for tunnelling in firm ground because the stable soil or rock can support the entire tunnel cross-section being excavated simultaneously. This approach allows for faster progress and eliminates the need for temporary supports like timbering or steel sets, which are required in weaker ground conditions. By removing the whole face at once, the risk of collapse is minimized when the surrounding material possesses sufficient inherent strength to maintain stability. Consequently, this method is most efficient and widely adopted specifically for projects involving hard, competent geological formations.
For B.G. single track railway, the height of the tunnel above top of rails should be
Explanation:
In a Broad Gauge single track railway, a clear height of 6.7 m to 7.3 m above the rail level is mandated to ensure safe passage for standard locomotives and freight wagons. This specific range accommodates the maximum permissible load height while providing sufficient vertical clearance for overhead signaling equipment and catenary wires. Maintaining this dimension prevents collisions with the tunnel roof and allows for the necessary safety margins during train operations. The design balances structural integrity with operational efficiency to handle heavy traffic loads effectively. Adhering to these standards is critical for preventing derailments and ensuring passenger safety in confined tunnel environments.
Pick up the correct statement from the following during tunnel excavation,
Explanation:
Maintaining safe atmospheric conditions is critical during tunnel excavation to protect worker health and prevent asphyxiation or poisoning. Hydrogen sulphide limits prevent respiratory irritation, carbon monoxide thresholds avoid hemoglobin binding that causes oxygen deprivation, and ensuring oxygen levels stay above 19.5% guarantees sufficient breathing capacity. Since all these specific concentration limits are standard safety requirements for underground environments, the statement encompassing all of them is the correct choice.
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