Hydraulic muck handling system for tunnel boring machine

Mining or in situ disintegration of hard material – Hard material disintegrating machines – Rotary cutter head with advance direction coincident or...

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405138, E21D 912

Patent

active

06142577&

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a tunnel boring method and a tunnel boring machine for digging into a working face by a cutter disk to bore a tunnel while discharging excavated earth with a carrying fluid comprising mainly water, and more particularly to a tunnel boring method and a tunnel boring machine which are suitable for digging into the ground having a non-disintegrative feature.


BACKGROUND ART

Working faces to be dug in by tunnel boring machines are divided into the ground having a not-disintegrative geological feature and the ground having a disintegrative geological feature. When digging in the ground having a disintegrative geological feature, a method called a slurry pressure technique is generally used. According to this method, a water-tight chamber enclosed by a partition wall is formed on the back side of a cutter disk, and compressed water is supplied to the chamber to fill it with water under pressure, thereby preventing a collapse of the working face with the water pressure of the compressed water. Further, the earth excavated by the cutter disk is collected in a lower portion of the chamber, and then discharged along with the compressed water rearwardly of the partition wall under the pressure of the compressed water in the chamber through a discharge pipe connected to the partition wall.
Such a slurry pressure technique is extremely complicated and expensive in equipment because sealing mechanisms are required between a body of the tunnel boring machine and the surrounding natural ground and between the exterior and interior of the boring machine body for keeping water-tight the chamber on the back side of the cutter disk. For that reason, the slurry pressure technique is used only when digging in the ground having a disintegrative geological feature, and a non-pressure technique is generally used when digging in the ground having a non-disintegrative geological feature.
As a tunnel boring machine operable in a non-pressure manner to dig into ground having a non-disintegrative geological feature, there is a known conventional one wherein carrying-out means such as a belt conveyor or a screw conveyor is disposed on the back side of a cutter disk. The earth excavated by the cutter disk is discharged rearward by the carrying-out means.
Further, to make smaller the size of the carrying-out means and reduce frequency in occurrence of troubles thereof, JP, Y, 4-49274 and JP, B, 4-11720 propose a tunnel boring machine using a jet pump as carrying-out means. According to this proposal, a hopper is disposed in a lower portion of a chamber formed between a cutter disk and a partition wall, and the earth excavated by the cutter disk is collected in the hopper. The jet pump having an earth take-in port formed in its casing is attached to a bottom portion of the hopper, and a discharge pipe is connected to a casing outlet of the jet pump. Compressed water is supplied to the jet pump through a piping from a supply pump provided rearwardly of the boring machine. The compressed water is accelerated by a nozzle of the jet pump, and then depressurized in a throat portion downstream of the earth take-in port to produce a negative pressure. With a water flow developed under the negative pressure, the earth in the hopper is discharged through the earth take-in port and then the discharge pipe.


SUMMARY OF THE INVENTION

In an earth carrying system using such a jet pump, however, if a foreign matter enters the accelerating nozzle and makes it clogged, earth is accumulated in the throat portion and the casing provided with the earth take-in port, causing the interior of the casing to be gradually brought into a closed state. Eventually, it becomes impossible to propel the earth further. In the event the earth can thus no longer be propelled to advance, repairing steps of disassembling the casing of the jet pump and cleaning up the interior of the jet pump are required. This raises a problem that since the tunnel boring machine is kept in a shutdown state during the repairing steps and a

REFERENCES:
patent: 3350889 (1967-11-01), Sturm
patent: 4116487 (1978-09-01), Yamazaki et al.
patent: 4165129 (1979-08-01), Sugimoto et al.
patent: 4629255 (1986-12-01), Babendererde
patent: 4844656 (1989-07-01), Babendererde et al.

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