| 摘要 |
<p>A nozzle assembly (14) for enlarging an inground passageway (18) produced by, for example, a boring device comprises an elongate nozzle body (20) defining an interior cavity (22) adapted to receive fluid under pressure from an external source, and at least one arrangement of outwardly facing adjacent stepped surfaces which provide longitudinally spaced cutting jets (44A, 44B; 46A, 46B) directed normal to the movement of the nozzle assembly (14) as it moves through the passageway, in order to progressively enlarge the passageway.</p> |
