| 摘要 |
PROBLEM TO BE SOLVED: To construct a continuous underground wall having width larger than the inside measurement in the direction of the thickness of a cover coated on the upper part of a cutter post deeper than the surface of the earth or deeper than a certain depth by horizontally moving the cutter post while circulating an endless chain having a cutting edge. SOLUTION: Within the overall circumference of the cutter post 3, the widening type endless chain 41 having the cutting edge 41a for cutting the ground with the width larger than the inside measurement in the direction of the thickness of the cover 5 coated on the upper part of the cutter post 3 is put on over the section from the shallowest part A of the ground required to be improved to the lower end part of the cutter post 3 on the one side for the center line of the cutter post 3, a standard type endless chain 42 having a cutting edge 42a for cutting the ground with the width smaller than the inside measurement of the cover 5 is put on the remaining section, and the widening type endless chain 41 is reciprocated within a range of insertion of the cutter post 3 in the ground.
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