Apparatus for detecting position of underground excavator and ma

Hydraulic and earth engineering – Underground passageway – e.g. – tunnel – Boring

Patent

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Details

405138, 175 45, 324346, E21B 4709, E21D 906, G01C 1500, G01V 312

Patent

active

052403505

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to an apparatus for detecting the position of an underground excavator which is excavating underground, and, more particularly, to a position detection apparatus and its magnetic field producing cable for an underground excavator for use in guiding two underground excavators towards each other underground.


BACKGROUND ART

In a case where a submarine tunnel is formed, it is impossible to form many shafts from which underground excavators are started. Moreover, it is difficult to discharge excavated sediment. What is even worse, there arise many risks in a case where long distance excavation is performed by a single underground excavator. Accordingly, in a case where a submarine tunnel is formed, two underground excavators are started toward each other in order to shorten the distance of excavation made by the underground excavator. Then, the tunnels respectively excavated by the two underground excavators are joined to each other under the ground.
However, if the centers of the two underground excavators are deviated laterally or vertically at the junction, the two tunnels may not join together. Furthermore, if the centers of excavation of the two excavators are not aligned, the outbreak increases undesirably, the number of the excavation operations is increased and the quantity of agent to be injected is enlarged, causing the construction cost to be raised excessively. Therefore, the centers of the excavation made by the two excavators must be aligned to each other. Accordingly, the relative position between the two underground excavators must be detected to correct the positional deviation. Hitherto, the positional deviation taken place between the two underground excavators has been corrected by detecting the positional deviation between the two underground excavators and the designed tunnel line or the position with respect to a reference point such as the start point. Thus, the error correction is performed in accordance with the positional deviation thus-obtained.
Hitherto, the position of the underground excavator positioned underground has been obtained by the following methods:
(1) The position of the underground excavator from a reference point and the deviation from the designed line are obtained by a measurement performed underground by means of a transit or the like.
(2) An optical beam transmitting device for generating coherent light such as a laser beam is disposed in the shaft from which the underground excavator is started. The designed tunnel line is irradiated with the above-described device so as to read light spots on a target attached to the underground excavator. As a result, the position, the deviation and deflection angle of the underground excavator made from the start shaft are obtained.
(3) An azimuth gyro compass, a pressure type settlement gauge, an inclination gauge and a distance meter acting by making a segment length built up in the tunnel to be a reference are combined to one another so as to obtain the relative position from the reference position.
However, each of the above-described conventional methods for obtaining the position of the underground excavator encounter the following problems, causing a difficulty to arise when accurate underground joining is required.
A problem of a practical use arises in method (1) because the real-time measurement cannot be performed since many measuring points must be required when a bent tunnel is excavated. Furthermore, in method (2) there arises a necessity of moving the optical transmitting device to a proper position if the tunnel designed line is bent because the laser beams emitted from the start shaft cannot be applied to the target. Furthermore, the laser beam cannot be directly applied to cover the overall length of the designed line. Therefore, whenever the optical transmitting device is moved, the relative positional relationship among the target, the optical measuring device and the tunnel designed line must be actually measured. Then, the designed route must be ob

REFERENCES:
patent: 3549985 (1970-12-01), Penland
patent: 4387340 (1983-06-01), Peterman
patent: 4678371 (1987-07-01), Yamamura et al.
patent: 4714888 (1987-12-01), French et al.
patent: 4806869 (1989-02-01), Chau et al.
patent: 4936708 (1990-06-01), Perry
patent: 5014008 (1991-05-01), Flowerdew
patent: 5107938 (1992-04-01), Okamoto et al.

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