JPH0499986A - Surveyer for shield excavator front - Google Patents

Abstract

PURPOSE:To enable precise detection of soil state at a distant front by arranging one of a multitude of emission electrode pairs on a cutter face (CF) and the other electrode at a symmetrical position to the shield outer surface against a pair of reception electrodes in the center of the CF. CONSTITUTION:When a constant current is sent from an emission electrodes pair 16R and 16L, an emission current is supplied in the ground wall in the state that the electrodes 16R1, 16L1 on the CF 12 side and the electrodes 16R2, 16L2 on the shield main body side are common poles. Therefore, the current line due to the electrodes pair 16R and 16L focus in the center of the CF 12, the current density in the distance from the CF 12 increases, and thus the component perpendicular to the CF 12 increases. And so, even if there is the CF 12 as an electric conductor, the supplied current reaches distant into the ground and the relative resistance in the distance in the ground wall can easily be detected. In other words, if the emission current from the electrodes pair 16R and 16L is set equally and the soil in the front is homogeneous, no electric potential difference appears at the reception electrodes pair 14. Once the homogeneity disrupts, electric potential difference appears at the electrodes pair 14 and therefore, soil change or obstruction existence are detected.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a rock exploration device in front of shield excavation, and more particularly to an improvement of a rock exploration device using a convergence control method using resistivity measuring electrodes.

[Conventional technology]

Conventionally, when excavating a tunnel using a shield machine, knowing the condition of the ground in front of the excavation is important for construction management, and various detection methods have been used. As a device for detecting soil quality in front of a face of this type, there is one that uses a resistivity method to detect by attaching a group of electrodes for measuring resistivity to the front surface of a cutter head. This is done by supplying a current to one pair of electrodes in the electrode group and transmitting it to the ground to generate an electric field in the ground, measuring the potential with the other pair of electrodes and calculating the resistivity distribution of the ground. It is designed to detect soil conditions and the presence or absence of obstacles. Usually, this device is composed of a resistivity measuring electrode array in which a plurality of electrodes are arranged at regular intervals, and is known as a Wenner electrode array or a dipole electrode array.

[Problem to be solved by the invention]

However, in the above-mentioned conventional device, the cutter head surface to which the electrode is attached is made of a metal conductor, so most of the current supplied from the transmitting electrode flows to the cutter face side as a conductor, causing the current to be measured. There was a problem in that only a small amount of current was transmitted to one side of the mountain. For this reason, the conventional device has the disadvantage that it can only detect the soil condition in a shallow area near the cutter face. The present invention focuses on the above-mentioned conventional problems, and provides an equipment for detecting other mountains in front of shield excavation, which is capable of transmitting a current far away from the excavated ground to reliably detect the soil condition of the distant ground. With the goal.

[Means to solve the problem]

In order to achieve the above object, the device for detecting the ground in front of the shield excavation according to the present invention is a device for exploring the soil in front of the excavated ground by providing a shield machine with a resistivity measuring electrode. A receiving electrode pair is provided in the center of the cutter face of the machine, a plurality of transmitting electrode pairs are arranged symmetrically with respect to the receiving electrode pair, and one electrode of the transmitting electrode pair is attached to the cutter face surface,
The other electrode is placed and attached to the outer peripheral surface of the shield machine.

[Effect]

According to the present invention, a current can be supplied so that the electrodes on the cutter face side of the plurality of transmitting electrode pairs have the same polarity. Therefore, the lines of electric force from the pair of transmitting electrodes converge in front of the center of the cutter face, are prevented from short-circuiting and flowing toward the cutter face made of a metal conductor, and reach the front return part of the earth. Since the current convergence point is the central part of the multiple transmitting electrode pairs, the receiving electrode pair attached to this point can measure the potential at a distant position and detect the specific resistance, so it is possible to detect the soil quality at a distance. This makes it possible to detect living objects.

【Example】

EMBODIMENT OF THE INVENTION Below, the specific Example of the exploration device in front of shield excavation based on this invention is described in detail with reference to drawings. FIG. 1 is a sectional view of a shield machine 10 showing the arrangement of electrodes in an exploration device in front of shield excavation according to an embodiment. As shown in this figure, a receiving electrode pair 14 consisting of a pair of electrodes 14M and 14N arranged at a constant interval is provided at the center of the cutter face 12 of the shield machine 10. This is attached via an insulating plate to a slit opening/closing device for soil inflow, which is formed on the cutter face 12 so that the electrodes 14M and 14N are exposed on the surface of the cutter face 12. On the other hand, in order to supply and transmit current to the earth, two transmitting electrode pairs 16R and 16L are provided in the embodiment. These are arranged point-symmetrically with respect to the receiving electrode pair 14 placed at the center of the shield machine 10. Specifically, the receiving electrode pair 14 is placed along the diameter line of the cutter face 12.
It is set and arranged so that it is located equidistant from. Then, one electrode 16R5 in the other transmitting electrode pair 16R
is attached to a position near the outer edge of the cutter face 12, and the other electrode 16R2 paired therewith is disposed on the outer peripheral surface of the shield machine 10, particularly on the main body side. These electrodes 16R1, 16R are arranged along a plane that includes the arrangement line of the receiving electrode pair 14 (the diameter line of the cutter face 12), and are set to be located on the same plane as the receiving electrode pair 14. ing. Further, the transmitting electrode pair 16L and the transmitting electrode pair 16L, which are located at symmetrical positions with the transmitting electrode pair 16R and the receiving electrode pair 14 in between, are arranged in the same way, with one electrode 16L located near the outer edge of the cutter face 12 surface, and the other electrode The electrodes 16L2 are respectively arranged on the outer peripheral surface of the main body of the shield machine 10. In this case as well, the picture electrodes 16L, . . . 16L2 are set to be located on the same plane as the receiving electrode pair 14. Each electrode of these transmitting electrode pairs 16R and 16L is connected to the slit opening/closing device through an insulating plate on the cutter face 12 side in the same way as the receiving electrode pair 14, and on the shield body side, an insulating plate is also connected to the window opened in the skin plate. Attached via. Electrodes for measuring resistivity 14 and 16 arranged in this way
R,, 16L, the transmitting electrode pair 16R, 16L
Oscillators 18R and 18L are connected to each of the oscillators 18R and 18L to transmit a constant current toward the ground. In this case, in the transmission electrode pair 16R116L, the cutter face 1
The electrodes 16R2 and 16L+ arranged on the second side have the same polarity when transmitting current. For this reason,
A polarity setter 20 is connected to the oscillators 18R and 18L,
This ensures that the transmission polarity from one transmission electrode pair 16R and the transmission polarity from the other transmission electrode pair 16L are the same. This is controlled by a computer 22 that manages the polarity setter 20. On the other hand, a voltmeter 24 for measuring the received voltage is connected to the receiving electrode pair 14, and this input signal is sent to the signal processing device 26.
I am trying to incorporate it into The signal processing device 26 calculates the apparent resistivity based on the measurement signal and outputs it to the computer 22. In response to input signals, the computer 22 outputs data on the soil quality of the ground and obstacles to an external output device 28 for printing out or displaying on a monitor. In the shield excavation front exploration device configured in this way, when a constant current is transmitted from the transmitting electrode pair 16R, 16L, the electrodes 16R, 16L on the cutter face 12 side and the electrodes 16R2, 16L2 on the shield body side are the same. Electric current is transmitted and supplied to the ground in the polar state. Therefore, as shown in FIG. 2, the current lines formed by the pair of side transmitting electrodes 16R and 16L converge at the center of the cutter face 12, and the current density at a point away from the cutter face 12 is determined by, for example, the Wenner method or This is larger than the dipole method, and the component perpendicular to the cutter face 12 increases. Therefore, due to the presence of the cutter face 12 as an electric conductor, this supplied current reaches far underground, making it possible to easily measure the specific resistance far away from the ground. That is, when the transmission currents from the side transmitting electrode pairs 16R and 16L are made equal, no potential difference will appear in the receiving electrode pair 14 if the soil quality in front is uniform, but the uniformity will be disrupted due to changes in soil quality or obstacles. Then, a potential difference appears in the receiving electrode pair 14, and changes in soil quality and obstacles can be detected. In addition, in the above embodiment, two transmitting electrode pairs 16R116L
However, three or more pairs of transmitting electrodes may be provided. In this case, the transmitting electrodes on the cutter face 12 side may be placed at the same distance from the receiving electrode pair 14, and the transmitting electrode pairs may be attached at equal intervals.

【Effect of the invention】

As explained above, the shield excavation front exploration device according to the present invention is provided with a pair of receiving electrodes in the center of the cutter face of a shield machine, and a plurality of pairs of transmitting electrodes are arranged symmetrically with respect to the pair of receiving electrodes. , and one electrode of this transmitting electrode pair is attached to the cutter face surface, and the other electrode is arranged and attached to the outer peripheral surface of the shield machine, so that the current supplied from the transmitting electrode is connected to the cutter head as a conductor. Regardless of the presence of the current, most of the current can be transmitted to the ground side that is the object of measurement, and the excellent effect of being able to reliably detect the soil condition of the front return area can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an exploration device in front of shield excavation according to an embodiment, and FIG. 2 is an explanatory diagram of a current transmission state by the same device. 10... Shield machine, 12... Cutter face, 14... Receiving electrode pair, 16R,
16L... Transmission electrode pair, 20... Polarity setting device, 24... Voltmeter, 26... Signal processing device.

Claims (1)

[Claims] 1) In an apparatus for exploring the soil in front of an excavated ground by providing a shield machine with a resistivity measuring electrode, a receiving electrode pair is provided in the center of the cutter face of the shield machine, and a plurality of transmitting electrode pairs are provided in the cutter face of the shield machine. A shield excavation front which is arranged symmetrically with respect to a pair of receiving electrodes, one electrode of the pair of transmitting electrodes is attached to the cutter face surface, and the other electrode is arranged and attached to the outer peripheral surface of the shield machine. exploration equipment.