JPH0842284A - Excavation method for shield tunnel - Google Patents

Abstract

PURPOSE:To decide a state in the front of a tunnel caused by reflected waves of elastic waves to execute excavation control by providing an oscillator having resonance band, etc., less than specific one to a revolving excavation blade of a shield machine to obtain signals. CONSTITUTION:Oscillation and reception sensors C and H of elastic waves D are mounted to a revolution section of a cutter, and the sensors C and H are rotated with the excavation to cover the whole front of a facing. At that time, an oscillator and a receiver having a resonance band less than 50kHz are mounted to an excavation blade, and a pulse power source is supplied to an oscillating pulser C from a signal processor on a shield machine side. The elastic waves D passing through muddy water G run against a bedrock E to convert into reflected waves F, and they are detected by the receiving sensor H. After that, the detected signal is converted into voltage, and it is supplied to a personal computer of a central signal processor through a rotary connector. According to the constitution, the thickness of the muddy water G of the facing is held constant through a sequencer controlling device, and rotational speed of the cutter and a driving jack are controlled to make it possible to promote safety of shield excavation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention was developed as a technique for safely excavating a shield tunnel without collapse of a cutting face or land subsidence.

[0002]

2. Description of the Related Art A boring survey is carried out before the shield excavation, but since it is carried out every several hundred meters, only a part of the soil condition can be grasped. We often encounter materials such as H steel and piles, and we spend valuable time dealing with them.
If it is possible to continuously grasp the state of the unexcavated area in front by a sensor such as an exploration device without stopping the excavation machine, the construction method should be examined and the necessary parts should be prepared during excavation according to the changes. Since it is also possible,
It can be expected to improve economic efficiency. Under such expectations, the front face exploration device using the electromagnetic wave method has become a reality and is becoming the mainstream, but in the present situation that electromagnetic waves do not penetrate muddy water, it is not possible to respond sufficiently depending on the excavation method. is there.

In the United States and the like, a method using Rayleigh waves has been tried, but it is an exploration with the excavating machine stopped, and the conditions for the forward exploration during excavation have not been satisfied.

[0004]

[Problems to be solved by the invention] A boring survey is carried out before the shield excavation. However, since it is done every several hundred meters, only a part of the soil condition is grasped. We often encounter H steel, piles, etc., which are construction materials in the past, and spend valuable time dealing with them.

If it is possible to continuously grasp the state of the unexcavated part in front by a sensor such as an exploration device without stopping the excavating machine, the construction method and preparation of necessary members are being excavated according to the change. Even if it is possible, it can be expected to improve the safety and economic efficiency of construction.

[0006]

The present invention replaces the electromagnetic wave (high frequency) of the conventional radar and accurately analyzes a reflected wave of an elastic wave (50 kHz or less) which has been impossible to use due to its poor resolution. It is a method of managing the condition of the cutting face. Figure 1 is a schematic view of the cross section of a face, Figure 2
Shows the relationship between the reflected wave, soil quality, and muddy water thickness. In Fig. 1, A: trigger, B: generator, C: transmission sensor, D: elastic wave, E: Mt.
F: reflected wave from the ground of elastic wave, G: muddy water, H: reception sensor, I: amplifier. Computer, G: shows a natural component signal. The electric signal generated by B is converted into an elastic wave by C. Each elastic wave has a characteristic according to the frequency. For example, in the case of an elastic wave of 50 KHz, it passes through the muddy water of G and is reflected on the surface of the E ground and is detected by H. The waveforms at C and H in this case are shown in FIG. Thus, from the relationship between the waveforms of C and H, as shown in FIG. 2, t1, t2, v
By obtaining 1, v2, it is possible to know G: thickness of muddy water, muddy water concentration, soil quality of face. Next, the 5 KHz elastic wave transmitted from C passes through the boundary between the mud and the ground and enters the ground, such as the boundary of the soil in the ground (for example, the boundary between sandy and silty), H-like steel. H: Reflected by a foreign substance, detected by the receiving sensor. As described above, the problem can be solved by installing the oscillator and the receiver having the resonance band or flat region of 50 KHz or less on the rotating excavating blade. Figure 3 shows the relationship between mud thickness and delay time at this time.
Figure 4 shows the relationship between mud concentration, soil quality and peak value.

Next, the measurement principle will be described. The transfer system is basically defined by the following model, that is, the characteristic of the linear time invariant system is defined by its impulse response h (t).

[0008] When an arbitrary signal f (t) is input to this system, the corresponding response g (t) is

[0009] It is expressed by the Naru convolution integral. This is an expression in the time domain, and when the Fourier transform is performed, the relational expression in the frequency domain

G (ω) = H (ω) · F (ω). ． ． ． ． ． (3) Here, G (ω) · H (ω) · F (ω) is the Fourier transform of g (t) · h (t) · f (t), and when FFT analysis is performed, each data is in the frequency domain and each frequency is It means that it can be divided into amplitude and phase information of the component. In an actual case, a measurement factor is added and the elastic wave transmission system is expressed as follows.

[0011]

[0012]

S is the transmission sensitivity of the transmission converter T1. M is the receiving sensitivity of the receiving transducer T2. α and β are transfer functions related to the coupling between the transducer and the propagation medium. A is the transfer function of the inspection target. When the transfer function of each part is used in this way, it is expressed as follows.

F1 (t) → s1 → β1 → ha → α1 → mII → g1 (t). ． (6) Therefore, the transfer function HA of the entire system is expressed as follows in the frequency domain.

HA = GA / F1 (ω) = S1 · β1 · β2 · MII. ． (7) For this transfer function HA (ω), the material A (the muddy water of the cutting face,
It contains a great deal of information about soil, and the relation between information and transfer function is as follows.

[0016] All of these affect the transfer function. Since the area in front of the shield is considered to be muddy water + ground, the face condition (muddy water concentration, muddy water thickness, cut face) can be measured by measuring the factor of the above materials (change in density → change in sound velocity and attenuation rate). Soil quality, obstacles in the direction of travel, etc.) can be determined.

[0017]

According to the present invention, as shown in FIG. 4, an elastic wave pulsar oscillator and a receiver of 50 KHz or less are installed in the cutter part of the shield machine. As shown in FIG.
By measuring t2, v1 and v2, the mud concentration, soil quality and foreign matter can be displayed on the image from the transfer function system, and the shield excavation can be safely performed.

[0018]

EXAMPLE An example of carrying out the present invention with a muddy water shield will be described. Figure 4 shows the front and side of the shield machine to which this device is attached. The elastic wave transmitting and receiving sensors are attached to the rotating part of the cutter. You can cover everything. Figure-5
[Fig. 3] is a flow chart showing the relation with the excavation of an elastic wave sensor. A is composed of an elastic wave transmitting pulsar, a receiving sensor and an amplifier base. The power source of the amplifier is from the E power supply device through the B slip ring and to the transmitting pulsar by D.
The pulse power shown in FIG. 2 is supplied from the machine side signal processor through the rotary connector. The elastic wave that has passed through the muddy water hits the ground and becomes a reflected wave, which is detected by the receiving sensor. The detected signal is converted into a voltage and supplied to the personal computer of the H central signal processing unit through the rotary connector.

This change in voltage is analyzed based on the judgment flow for soil and muddy water concentration shown in FIG.
Shield excavation can be performed safely by displaying foreign matter on the image and controlling the rotation speed of the cutter and the propulsion jack so as to keep the mud thickness of the face constant through the sequencer control device. The result of the front display at that time is shown in FIG.

[0020]

As described above, according to the present invention, unlike the conventional electromagnetic wave method, the information on the front of the excavation can always be obtained, and the excavation speed can be controlled by the information so that the cutting face does not collapse. It became possible to dig into.

[0008]

[0009]

G (ω) = H (ω) · F (ω). ． ． ． ． ． (3)

[0011]

[0012]

[Brief description of drawings]

Figure -1 shows a schematic diagram of the cross section of a cutting face and shows the relationship between the reflected wave and the soil and muddy water thickness.-2 The flow of analysis of elastic wave transmission, reception and ground component in Figure 1 is shown. Thing-3 The one that shows the relationship between v2 and soil quality in Figure 1. -4 shows the positional relationship between the acoustic wave transceiver of the shield machine and the magnetic sensor. -5 A schematic cross-sectional view of a shield machine of an example. -7 What is displayed on the front situation display CRT screen

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[Procedure amendment]

[Submission date] December 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

[Fig.-1] Schematic diagram of the cross section of the face and the relationship between the reflected wave, soil quality and mud thickness

FIG. 2 shows an analysis flow of elastic wave transmission / reception and ground component in FIG.

FIG. 3 shows the relationship between v2 and soil quality in FIG.

FIG. 4 shows a positional relationship between an elastic wave receiver and a magnetic sensor of a shield machine.

FIG. 5 is a schematic cross-sectional view of an example shield machine.

FIG. 6 shows a screen of a front situation display CRT.

Claims (3)

[Claims] 1. A rotating drilling blade of a shield machine is provided with 50.
A method in which an oscillator and a receiver having a resonance band or a flat band of less than kHz are attached, and the state of the cutting face (muddy water concentration, muddy water thickness) is judged by the obtained signal to manage the excavation. 2. A rotating drilling blade of a shield machine is provided with 50.
A method of managing excavation by determining the state in front of the cutting face by attaching a plurality of oscillators and receivers each having a resonance band or a flat region of kHz or less and processing the obtained signals by image processing. 3. A rotating drilling blade of a shield machine is provided with 50
A method to determine the soil quality of the face by installing an oscillator and a receiver that have a resonance band or flat region below kHz and using the obtained signal.