| 摘要 |
PROBLEM TO BE SOLVED: To provide a propulsion construction method for a small soil cover section, which construction method surely prevents ground subsidence upon constructing a tunnel in a small soil cover section passing under a road, etc., and employs a lubricant that does not react chemically on a backing material. SOLUTION: A cutter head 8 of a main shield 6a located on the left of a shield machine 1 is rotated to excavate the ground, and a slide jack 10 is stretched to propel the main shield 6a from a front trunk 3. As a result, an overcut portion is formed between the main shield 6a and the soil. When the overcut portion is left as it is, the soil around the main shield 6a become loose, which may leads to ground subsidence. To prevent ground subsidence and reduce a frictional force produced between the main shield 6a and the soil, the main shield 6a is propelled as the lubricant delivered from an injection unit 14 is injected by pressure into the overcut portion via an injection hole 13. COPYRIGHT: (C)2007,JPO&INPIT
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