In the post which is retired somewhat from the earth removal system null penetration pit and the said penetration pit which are used for the non

摘要

PROBLEM TO BE SOLVED: To provide a non-cut and cover method for a small-diameter pipe, eliminating a trouble such as ground deformation, etc., and increasing the per-span distance for laying small-diameter pipe, for example, to be approximately doubled, that is, to be increased to 100 m or above, and avoid the situation precluding piping and reduce the power cost of forming a main hole by providing an earth removal system for changing a diameter-of- pilot-hole enlarging method from consolidation to excavation.;SOLUTION: Drilling is started from a penetration pit toward a starting pit obliquely downward by means of a non-cut and cover boring machine provided with a flexible coupling rod whose tip has a drill head. The propulsive direction of the drill head is taken as horizontal at a prescribed place so as to drill a hole up to the starting pit. Furthermore, the drilling is conducted up to an arrival pit in order to form a pilot hole, the drill head is replaced for attachment by a back reamer, which allows the peripheral wall of the pilot hole to be excavated for the purpose of forming the main hole from the arrival pit to the starting pit. A sediment taking-in device is mounted on the back part of the back reamer and the small-diameter pipe to be laid is mounted on the back part of the sediment taking-in device. The inside of small-diameter pipe accommodates an earth removal pipe, whose one end is mounted on the back part of the sediment taking-in device and whose other end communicates with a vacuum unit. Taken-in sediment is drawn by suction and discharged to the side of the arrival pit through the removal earth pipe. An air valve for controlling the uptake of the sediment is installed within the sediment taking-in device.;COPYRIGHT: (C)2002,JPO