JPH03257396A - Method and apparatus for prospecting collapse of ground by shield method - Google Patents

Abstract

PURPOSE:To obtain a wide range of ground information quickly at a face by selecting a detection signal with a frequency thereof coinciding with a frequency of current from detection signals of a voltage based on currents varied in frequency flowing from a plurality of points in a circumferential direction of a shield excavator. CONSTITUTION:A plurality of electrode trains 14a-14c are mounted on a front skin plate 14 of a shield excavator 10 and the electrode trains 14a-14c are arranged at an equal angular interval with respect to the center of a excavator 10 and the electrode train 4b is positioned at the top thereof 10. The electrode train 14a-14c each comprise an energizing electrode to feed a current to a mud 15 in the perimeter of the excavator 10 and a ground 17 and a detecting electrode to detect a voltage based on the current and are arranged on an insulating body 16 fixed on the skin plate 12 at an equal interval. With such an arrangement, currents varied in frequency flow to the mud 15 and a detection signal alone the same in frequency as the current among those obtained with the detecting electrode is selected to be inputted into a signal processor 22.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for detecting collapse of the ground at a face portion during excavation by a shield excavator, and in particular, a method for detecting ground collapse by detecting underground resistivity. This invention relates to a ground collapse detection method using a shield construction method for detecting mountain collapse and its device.

[Conventional technology]

Generally, in the shield construction method, the collapse of the ground at the face of the shield excavator is detected for the purpose of adjusting the amount of backfill injection in response to changes in the face. In order to detect the collapse of the ground, changes in the thickness of mud between the shield excavator and the ground are measured.
A method is used to capture it as a change in specific resistance.

The method for detecting rock collapse due to resistivity is to attach a pair of current-carrying electrodes to the tip of a shield excavator, and then passing an electric current through the current-carrying electrodes into the muddy water. Voltage is detected by electrodes, and a composite resistivity consisting of the resistivity of the muddy water and the resistivity of the ground is determined from the detected voltage, and the collapse of the rock is detected by changes in this composite resistivity.

In addition, in order to detect a wide range of ground collapse in the circumferential direction of the shield excavator, a collapse detection device has been proposed in which multiple electrode rows consisting of energized electrodes and measurement electrodes are provided in the circumferential direction of the shield excavator. (Utility Model Application Publication No. 1-131186).

[Problems to be Solved by the Invention] However, the device described in Japanese Utility Model Application Publication No. 1-131186 switches each electrode row at predetermined time intervals to energize and measure, and the current passed through the muddy water is stable. In particular, as the number of measurement points increases, the measurement time is proportional to the square of the number of measurement electrode points. This makes it difficult to obtain and analyze data in real time when trying to obtain detailed rock formation conditions.

The present invention has been made in order to eliminate the drawbacks of the above-mentioned prior art, and provides a method and device for detecting ground failure using a shield construction method, which can quickly perform measurements at multiple locations in the circumferential direction of a shield excavator. It is intended to.

[Means and effects for solving the problem] In order to achieve the above object, the shield construction method of the present invention detects the specific resistance by passing an electric current through the muddy water around the shield excavator, and calculates the ratio In the rock collapse detection method of the shield method, which detects rock collapse based on changes in resistance,
Currents with different frequencies are passed through the muddy water from multiple locations in the circumferential direction of the shield excavator, and voltage detection signals having the same frequency as these currents are obtained to detect specific resistance at the multiple locations. It is said that

In addition, in order to carry out the above exploration method, the shield construction method rock collapse exploration device according to the present invention includes an electrode array consisting of current-carrying electrodes and detection electrodes arranged at a plurality of locations in the circumferential direction of the shield excavator. , connected to the current-carrying electrodes of each of these electrode rows, each of the current-carrying types. a plurality of power supplies that supply currents of different frequencies to the poles; a plurality of filters that are connected to the detection electrodes of the electrode array and pass voltage detection signals of the same frequency as the current supplied to the corresponding current-carrying electrodes; The present invention is characterized by comprising a signal processing device that calculates the resistivity at a plurality of locations in the circumferential direction of the seal l-'' excavator based on the outputs of these filters.

In the present invention configured as described above, currents with different frequencies are simultaneously passed into the muddy water around the shield excavator from the respective current-carrying electrodes of the electrode rows arranged at multiple locations along the circumferential direction of the shield excavator. . Then, the voltage caused by the current flowing into the muddy water is detected by the detection electrodes in each electrode row,
From the detection signals output by each detection electrode, a detection signal with the same frequency as the current flowing into the muddy water is extracted, and the extracted detection signals with a different frequency are processed in a signal processing device to distinguish between the muddy water and the ground. The condition of the face portion is detected by determining the composite resistivity consisting of the resistivity and monitoring the composite resistivity.

Therefore, since the detection signals of each frequency can be processed almost simultaneously in the signal processing device, the condition of the ground in the circumferential direction of the shield excavator can be quickly known in real time, and the condition of the face can be known quickly. Able to respond accurately to changes.

C Embodiment] Preferred embodiments of the ground collapse exploration method using the shield construction method and the device thereof according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a rock collapse exploration device using a shield construction method according to an embodiment of the present invention.

In FIG. 1, a front skin plate I2 of a shield excavator 10 has a plurality (three in the case of the embodiment) of electrode rows 1.
4a, 14b, and 14c are attachments. Each electrode row 14
a, 14b, and 14c are arranged at equal angular intervals with respect to the center of the shield excavator 10, and the electrode row 14b is located at the top of the shield excavator 10. Each electrode row 14as14b, 14c consists of a current-carrying electrode that flows current through the muddy water 15 and the ground 17 around the shield excavator 10, and a detection electrode that detects a voltage based on this current, and these electrodes are connected to the skin plate. They are arranged linearly at equal intervals on an insulator 16 fixed to 12.

Each electrode 18 of each electrode row 14a, 14b, 14c
are switching devices 20a, 20b, 20c such as relay boxes
It is connected to. Each switch 20a.

20b and 20c are connected to each electrode row '14a by a switching signal from the signal processing device F22.
, 14b, and 14c are switched and selected as current-carrying electrodes, and an arbitrary pair of the remaining electrodes is selected as detection electrodes. Each switch 20a, 20b, 20c also has an AC power supply 24a.
, 24b, 24c and bandpass filters 26a, 26b, 26
c is connected.

The AC power supplies 24a, 24b, and 24c have different output frequencies, for example, 20Hz, 30Hz, and 40Hz.
is supplied to the selected current-carrying electrodes of the electrode arrays 14a, 14b, and 14C. On the other hand, the bandpass filters 26a, 26
b, 26c are connected to the detection electrodes of the electrode rows 14a, 14b, 14c, and the AC power supply 24 whose center frequency f0 corresponds to
Among the voltages detected by the pair of detection electrodes that correspond to the output frequency of AC power supplies 24a, 24c,
Detection signals matching the output frequencies of 4b and 24c are passed and sent to amplifiers 28a, 24b and 24c.

The output sides of the amplifiers 28a, 24b, and 24c are connected to the signal processing device 22, and the signal processing device 22 receives the outputs of the amplifiers 28a, 24b, and 24c,
A composite resistivity of the resistivity of the ground and the resistivity of the ground 17 is determined and displayed on the display device 30.

The operation of the embodiment configured as described above is as follows.

The signal processing device 22 provides switching signals to the switching devices 20a, 20b, 20c, and switches the electrode rows 14a, 14b, 1, for example.
The outermost pair of electrodes 4c are selected as current-carrying electrodes, and the current-carrying electrodes are connected to AC power sources 24a, 24b, and 24c. As a result, an alternating current of 20 Hz is applied between the current-carrying electrodes in the electrode row 14a, 30 Hz is applied between the current-carrying electrodes in the electrode row 14b, and 40 Hz is applied between the current-carrying electrodes in the electrode row 14c.
flows through.

Further, the signal processing device 22 includes each electrode row 14a, 14b,
A pair of electrodes are selected as detection electrodes from among the electrodes other than the current-carrying electrodes 14c via switchers 20a, 20b, and 20c, and connected to bandpass filters 26a, 26b, and 26c. A pair of detection electrodes in each electrode row 14a, 14b, 14c detects the voltage between the electrodes, and outputs a detection signal corresponding to the magnitude of the voltage to bandpass filters 26a, 26b, 26c.

As mentioned above, the bandpass filters 26a, 26b, 26c
The center frequency matches the output frequency of the AC power supplies 24a, 24b, and 24c. Therefore, the bandpass filter 26
Of the input detection signals, a passes a 20Hz signal, a bandpass filter 26b passes a 30Hz signal, and a bandpass filter 26c passes a 40Hz signal and sends it to amplifiers 28a, 24b, and 24c. . amplifier 28
a, 24b, and 24c amplify the input signal and send it to the signal processing device 22.

The signal processing device 22 switches and takes in the output signal of each amplifier 28a, 24b, 24c every predetermined time, for example, every 10 amplifiers, and calculates the output signal of each electrode row 14a, 24c based on a well-known calculation formula.
Resistivity of muddy water 15 and ground mass 17 in parts 14b and 14C
A composite resistivity consisting of the resistivity and resistivity is determined, stored in a memory (not shown), and displayed on the display device 30. After that, the signal processing device 22 switches the switches 20a, 20b, 20
A switching signal is sent to C, and each electrode row 14a, 14b, 14
A detection electrode is selected by switching the electrodes c one after another, and the composite resistivity is determined in the same way.This is displayed on the display device 30, and a two-dimensional or three-dimensional map of the composite resistivity is created and displayed on the display device. 130 and printed out using a printer (not shown).

Further, after completing the combination of all electrodes other than the selected pair of current-carrying electrodes as detection electrodes, the signal processing device 22 selects the next pair of current-carrying electrodes and performs the same process as described above.

In this way, in the embodiment, currents of different frequencies are passed through the muddy water 15, and from among the detection signals obtained by the detection electrodes, only detection signals having the same current and frequency are selected and manually input to the signal processing device 22. By this, each electrode row 14a,
Even if current is supplied to the current-carrying electrodes 14b and 14c at the same time,
There is no interference of detection signals, and rapid data acquisition and processing is possible.
The state of the face detected by b and 14c can be detected in real time, and it is possible to respond quickly and accurately to changes in the face.

Note that in the embodiment, the amplifiers 28a, 24b,
Although a case has been described in which the signals from 24c are taken in in a time-division manner, they may be processed simultaneously using, for example, a plurality of central processing units. In addition, each electrode row 14a,
14b and 14c do not have to be arranged at equal angular intervals with respect to the center of the shield excavator 10, and the electrode array 14b does not need to be on the top of the shield excavator 10. Furthermore, the number of electrode rows is not limited to three. In the embodiment described above, a case has been described in which the current-carrying electrodes of each electrode row 14a, 14b, and 14c are a pair of separated electrodes, but a pair of adjacent electrodes may be a current-carrying electrode.

FIG. 2 shows another embodiment.

In the embodiment shown in FIG. 2, the electrode row 14 has a structure similar to that in which the plurality of electrode rows 14a, 14b, and 14C shown in the previous embodiment are integrated, and each electrode 18 is connected to a switch 20. It is. Then, the signal processing device 22 connected to the switch 20 selects any three pairs of electrodes in the electrode row 14 as current-carrying electrodes, connects them to the AC power sources 24a, 24b, and 24c, and connects them to the AC power sources 24a, 24b, and 24c. A current is passed through the muddy water from three locations in the direction, and any three pairs of remaining electrodes are sequentially selected as detection electrodes to pass through the bandpass filters 26a, 26.
b, connect to 26c.

In this embodiment as well, the same effects as in the previous embodiment can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, currents with different frequencies are passed through muddy water from multiple locations in the circumferential direction of a shield excavator, and a voltage detection signal based on this current is determined to match the frequency of the current. By selecting the frequency of the detection signal, the detection signals can be processed simultaneously, and information on the ground over a wide range of the face in the circumferential direction of the shield excavator 10 can be quickly obtained. It is possible to respond quickly and accurately to changes in parts.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a rock collapse detection device using a shield construction method according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of another embodiment. 10---Shield excavator, 14.14a, 14b,
14 c-----electrode row, 15-----one muddy water, 17
- Earth, 18 ---- Electrode, 22 - - Signal processing device, 24 a, 24 b, 24 c - - AC power supply, 2
6a, 26b, 26c---One-band filter.

Claims (2)

[Claims] (1) In the ground collapse exploration method of the shield construction method, which detects resistivity by passing an electric current through the muddy water around the shield excavator and detects the collapse of the ground based on the change in resistivity, the circumferential direction of the shield excavator is A ground collapse using a shield construction method, characterized in that currents with different frequencies are passed through the muddy water from a plurality of locations, and a voltage detection signal having the same frequency as these currents is obtained to detect specific resistance at the plurality of locations. Exploration method. (2) An electrode array consisting of current-carrying electrodes and detection electrodes arranged at multiple locations in the circumferential direction of the shield excavator, connected to the current-carrying electrodes of each of these electrode rows, and applying currents of different frequencies to each current-carrying electrode. A plurality of power supplies to be supplied, a plurality of filters connected to the detection electrodes of the electrode array and passing voltage detection signals having the same frequency as the current supplied to the corresponding current-carrying electrodes, and based on the output of each of these filters. , a signal processing device for determining resistivity at a plurality of locations in the circumferential direction of the shield excavator.