Which one of the following tunneling methods is used for laying underground sewers?
- ANeedle Beam Method
- BGerman Method
- CArmy MethodCorrect
- DNone of the above
Solution
Concept
Tunneling method for laying underground sewers
Formula
NONE
Step-by-step solution
1. The Army method (or Case Method) is a tunneling technique suited for small circular or horseshoe cross-sections. 2. It is typically used for tunneling in soft soil over short distances. 3. Therefore, it is commonly employed for laying underground sewers and pipes. Answer: C
Explanation
The Army method of tunneling, also known as the case method, is well-suited for soft soils and small cross-sections like those required for laying underground sewers. It involves driving rectangular wood frames or casing sections sequentially while excavating the soil. This provides continuous support during the installation of small utility pipes and sewer lines.
Why the other options are wrong
A) The Needle Beam method is mainly used for tunneling in firm soil or soft rock, not specifically for underground sewers. B) The German method involves driving upper and side headings for large railway or road tunnels. D) Option C is correct as the Army method is specifically used for laying underground sewers.
Shortcut
Needle Beam Method is used for soft soil and sewers.
Common mistake
Selecting the Needle Beam method instead of the Army method, which is specifically used for small sewer pipe tunneling.
Correct answer: C) Army Method