| 摘要 |
[083] The present invention provides a drilling assembly 3 for insertion of a caisson or casing 1, said drilling assembly 3 having two or more expanding drill bits 4 which are adapted to be driven by a drilling or rotation motive device 5, said expanding drill bits 4 being adapted to be arranged with respect to said caisson or casing 1 in use, so as form a hole or bore which substantially conforms to, or substantially overlaps with, the shape of said caisson or casing 1. Figure to be published: 8 |
