| 摘要 |
PURPOSE:To avoid an effect on a position sensing wire by the flowing of a stabilizing liquid by installing a protecting tube having an open-close-free slit in the longitudinal direction and constant length to the upper section of an excavating ditch and housing a position sensing wire. CONSTITUTION:A protecting tube H having an open-close-free slit 12 in the longitudinal direction is disposed into an excavating ditch B, and the upper end section of the protecting tube H is mounted to the upper section of the excavating ditch B by a protecting-tube mounting member 11. A position sensing wire 3 is housed into the protecting tube H from the slit 12, a slender parting plate 13 is engaged with engaging grooves 12a, 12a on both sides of the slit 12, and the slit 12 is closed. Accordingly, even when a stabilizing liquid is made to flow in the excavating ditch B, the generation of displacement such as transverse swing in the position sensing wire 3 can be prevented. |
