| 摘要 |
On either side of the construction to be produced, the elements which will constitute, partially or completely, the lateral walls of the construction are buried obliquely by sinking or hammering for example, or alternatively two lateral holes are obliquely hollowed out in order subsequently to produce therein the oblique lateral walls of the construction so that at the upper end these two lateral walls are only a small distance apart. Application to the production of relatively small-sized narrowings. <IMAGE>
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