PURPOSE: To improve the sealing properties of the front end of a casing pipe while preventing the trouble of an opening-closing section.
CONSTITUTION: A valve body 3 abutted against an opening section 3 at the front end of a casing pipe 1 and movably borne in the axial direction of the casing pipe 1 between a place where the opening section 2 is closed and a place where downward falling-off is prevented is mounted. The opening section 2 is automatically opened and closed surely in response to the penetration and extraction of the casing pipe 1 and the sealing properties of the opening section 2 are improved, and the opening section 2 has a simple constitution in which a drive mechanism for opening and closing is not used, thus reducing damage and trouble.
| JPS6038773 | [Title of the device] Drainage material |
NISHIHATA HIROSHI
KANAYAMA HIROYUKI
