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A Self-Learning Manual - Institution of Engineers Mauritius

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A <strong>Self</strong>-<strong>Learning</strong> <strong>Manual</strong><br />

Mastering Different Fields <strong>of</strong> Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU<br />

Level One (Core FAQs)<br />

Part II: Pipe Ramming and Microtunneling<br />

1. What is the difference between pipe jacking and micro-tunneling?<br />

(M1)<br />

Pipe jacking is a general technique <strong>of</strong> the installation <strong>of</strong> pipes with a<br />

tunneling shield in front and the pipes are jacked from a jacking pit to a<br />

receiving pit. The tunneling shield for pipe jacking can be electrical and<br />

mechanical equipment for conducting the excavation work or it can be a<br />

manual shield for workers going inside the shield to carry out manual<br />

excavation. For microtunneling, it is a kind <strong>of</strong> pipe jacking <strong>of</strong> small sized<br />

non-man-entry pipes which are remotely controlled. In general, there are<br />

two common types <strong>of</strong> micro-tunneling machines:<br />

(iv) Pressurised slurry<br />

Similar to the Pressurised slurry TBM, excavated material is<br />

transported from the excavation face to the surface suspended in a<br />

slurry.<br />

(i) Auger machine<br />

Excavated material is transported from the excavation face to the drive<br />

pit through a cased screw auger.<br />

2. Does microtunneling refer to tunnel size less than 1,000mm? (M1)<br />

The international definition <strong>of</strong> microtunneling includes pipe with diameter<br />

up to 1,000mm only. However, in the United States, it allows for larger pipe<br />

size when defining microtunneling in which pipe with diameters up to 144<br />

inches are also counted within the ambit <strong>of</strong> microtunneling.<br />

The basic concept <strong>of</strong> microtunneling has changed gradually owing to<br />

recent technological developments and past experience. For instance, the<br />

use <strong>of</strong> alignment control system with advanced surveying techniques<br />

allows for longer drives with good control and curved microtunneling. The<br />

use <strong>of</strong> automatic lubrication system enhances lower jacking forces. The<br />

employment <strong>of</strong> gripper in microtunneling machines helps develop<br />

adequate loads on cutter discs for cutting rock.<br />

3. What are the situations which warrant the use <strong>of</strong> microtunneling<br />

instead <strong>of</strong> other trenchless methods?<br />

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