| 摘要 |
The invention concerns a method for enhancing resistance to external pressure in a tube installed in a previously lined borehole, providing a passage through its tube of reduced dimension. Said method is characterised in that it consists in lowering the tube in a first shape (2) whereof the dimensions are smaller than the reduced section, shaping it to enable it to shift from said first form to a second substantially cylindrical shape (3) having a dimension larger than the reduced section and expanding it by moving a cylindrical expanding mandrel through the tube whereof the expansion value ranges between 2 and 10 % of the value of the external diameters. |
