The core barrel for rock core picking, being granted the drill rod and

摘要

PROBLEM TO BE SOLVED: To provide a rock-core extracting core barrel not to roughen an excavated hole wall by the flow of a sludge. ;SOLUTION: A second outer tube assembly 12 is unitedly provided through water passing gaps 23, 25 inside a first outer tube assembly 11 to axially move as it rotates. An inner tube assembluy 13 is slidably fitted inside the second outer tube assembly 12 through water passing gaps 24, 26. The inner tube assembly 13 is engaged with or disengaged from the second outer tube assembly 12 by a latch device 14.;COPYRIGHT: (C)1999,JPO