JP2002168961A - Working face forward probing method and probing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working face forward probing method and a probing device capable of precisely obtaining physical properties and a position of a rock bed ahead of a tunnel working face or a ground ahead of a shaft working face. SOLUTION: A solitary wave 30, which is an elastic wave having a property that the waveform is not collapsed during propagation into the rock-bed 18 or the ground, is inputted into the rock-bed 18 ahead of the working face 17 or the ground, and a reflected wave of the solitary wave 30 reflected from a reflecting object in the rock-bed 18 or the ground is detected. The physical properties and the position of the reflecting object are obtained based on the detected reflected wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for exploring a front face of a face suitable for excavation work in a state where the front face of the face is unknown, such as a bedrock of a tunnel or a ground of a shaft.

[0002]

2. Description of the Related Art For example, when excavating a tunnel, if there is a fault or a soft crush zone on the bedrock in front of the face, an accident such as collapse of the face when the face reaches the fault or crush zone may occur. There is. In particular, if there is groundwater in the fault or shatter zone, the face is likely to collapse, making excavation difficult. However, there is no reliable method other than survey boring for exploring the physical properties of rocks in front of the face and the location of faults and shatter zones, and the judgment on the necessity of face face reinforcement, its range, and reinforcement method tends to be delayed. It is in.

In the case of excavating extremely soft rock, even if the rock is changed to a hard rock in front of the face, it can be dealt with by a measure of changing the excavation method. It may not be so high, but in this case it is worth exploring to determine the extent of reinforcement of the soft rock mass.

Conventionally, when exploring the front of a face, an elastic wave is generated by hitting the face with an air gun, a water gun, or artificial means, and the elastic wave is input into the rock and provided on the same face. Attempts have been made to detect reflected waves reflected from a reflection target such as a fault or a crush zone in front of the face by one or more pickups, and thereby determine the distance to the reflection target.

That is, an attempt is made to calculate the difference between the actual arrival time of the reflected wave and the reference arrival time calculated from the elastic wave transmission velocity of the rock, and to determine the distance to the fault or crush zone from this difference. Has been done.

[0006]

However, in the conventional exploration method, an elastic wave is generated by hitting the face with an air gun, a water gun or artificial means, so that the waveform of the elastic wave is controlled. Therefore, not only is the waveform different from each other, but also the waveform is different each time, and since various phase and wavelength elements are included, there is a problem that the waveform is deformed in the process of propagating through the rock.

For this reason, a reflection object on which an elastic wave is reflected,
For example, when there are a plurality of faults, shatter zones, etc., only the arrival time of the P wave (longitudinal wave) is measured, despite the fact that the reflected wave detected by the pickup contains a plurality of reflected waves. In addition, the number and characteristics of reflected waves reflected from a plurality of reflection objects must be ignored and analyzed. For this reason, the distance to the reflection target such as a plurality of faults and shatter zones could not be accurately grasped, and the physical properties of the reflection target could not be determined at all.

An object of the present invention is to solve such a problem, and the physical properties such as a fault or a crush zone in the rock in front of the tunnel face or the ground in front of the shaft in the shaft are considered. It is an object of the present invention to provide a method and a device for exploring a face in front of which a position can be obtained more accurately.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method and an apparatus for exploring a front face of a face, and is constituted as follows in order to solve the above-mentioned technical problem. That is, the front face exploration method of the present invention, an elastic wave having a characteristic that the waveform does not collapse during propagation in the rock or the ground, is input into the rock or the ground in front of the face, and the rock or the ground. A reflection wave of the elastic wave reflected from the reflection target is detected, and a physical property and a position of the reflection target are obtained based on the detected reflection wave.

[0010] Further, according to the present invention, there is provided an apparatus for exploring a face in front of a rock face which creates an elastic wave whose waveform does not collapse while propagating in the rock or ground; An elastic wave input unit for inputting, and a reflected wave detecting unit for detecting a reflected wave of the elastic wave reflected by the reflection object in the rock or the ground are provided.

Next, each component will be described. (Wave-making means) A means for generating an elastic wave such as a solitary wave or a sine wave, and an oscillator can be exemplified. (Elastic Wave Input Means) As the elastic wave input means, a hydraulic jack can be exemplified. By operating the hydraulic jack at the timing of the elastic wave, the elastic wave can be converted into pressure fluctuation and input to the rock or ground. (Reflected wave detecting means) As the reflected wave detecting means, a hydraulic jack can be exemplified. In this case, a preload is applied to the rock or ground from the hydraulic jack, and a reflected wave is detected as a pressure fluctuation of the hydraulic jack.

According to the present invention, an elastic wave whose waveform does not collapse is used when propagating in the rock in front of the tunnel face or in the ground in front of the shaft face, so that the reflected wave can be reliably detected. Further, even when there are a plurality of reflection objects, it is possible to accurately determine the physical property, position, and number of each reflection object from distinguishing the reflected waves from each reflection object and the polarity of the reflected waves.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method and an apparatus for exploring a front face of a face according to the present invention will be described below in detail with reference to the drawings. Here, a case where the present invention is applied to a forward search of a tunnel face will be described.

FIG. 1 shows a front face exploration apparatus 1 according to the present invention.
Indicates 0. The front face exploration apparatus 10 inputs an elastic wave by applying a pressing force instead of applying an impact to the rock. Here, the force level or the deformation amount of the rock is controlled by controlling the solenoid valve.

That is, the front face exploration apparatus 10 includes, as wave-forming means for generating an elastic wave, a wave-making apparatus 11 such as an oscillator, and an amplification apparatus 12 for amplifying the elastic wave created by the wave-making apparatus 11. And a hydraulic pressure conversion device 13 for converting elastic waves into hydraulic pressure, and an input detection hydraulic jack 15A and a detection hydraulic jack 15B connected to the hydraulic pressure conversion device 13. Here, the solitary wave 30 (FIG. 2) is used as the elastic wave for the reason described later.

Between the hydraulic chambers (not shown) of the hydraulic jacks 15A and 15B and the hydraulic converter 13, pressure converters 16A and 16B and valves V1 and V2 are further connected in series. . As the pressure transducers 16A and 16B, for example, a pressure measuring sensor such as a foil gauge or a differential transformer type can be used.

The hydraulic jack 15A for input detection is for inputting the solitary wave 30 produced by the wave-making means 11 into, for example, a bedrock 18 in front of the tunnel face 17 and is fixed to the tunnel face 17 by an anchor 19. ing.

The detection hydraulic jack 15B detects a reflection object of the solitary wave 30 reflected from an object to be reflected in the bedrock 18, that is, a fault or a crush zone.
It is fixed to the face 17 by an anchor 19.

A constant hydraulic pressure is constantly applied to these hydraulic jacks 15A, 15B by a hydraulic pressure converter 13, whereby the pistons 20A, 20B are provided.
Thus, a constant preload is applied to the face 17.

The front face detecting device 10 includes a measuring device 21 for measuring pressure signals output from the pressure converters 16A and 16B, and an A / D converter for converting the output of the measuring device 21 into a digital signal. 22 and the A / D converter 22
Connected to the computer 23 and the computer 2
3 connected to a data recorder 24.

Next, each component described above will be described in detail. The wave making device 11 includes a rock bed 18 in front of a face 17.
An elastic wave whose waveform does not change even when propagating in the inside is created. In the present embodiment, as shown in FIG. 2, a solitary wave 30 is used as an elastic wave. Here, the solitary wave 30 is used for the following reason.

That is, when the medium through which the elastic wave propagates is not a perfect elastic body, the viscosity causes attenuation of the elastic wave.
Amplitude attenuation due to viscosity is obtained by equation (1).

[0023]

U = u ₀ · exp ((− ω / 2QC) · x) where u: amplitude attenuation u ₀ : amplitude of reference point ω: angular frequency C: propagation velocity Q: represents the attenuation characteristic of the medium Dimensionless number x: distance to reflection target Equation 1 indicates that a vibration wave obtained by combining a plurality of vibration waveforms is
This shows that the higher the angular frequency of the waveform constituting the composite wave is due to the viscosity of the medium, the greater the attenuation. In other words, it shows that the elastic wave having a complicated waveform is deformed in the process of propagating the vibration wave to the rock 18 (FIG. 1) which is not a completely elastic body.

Therefore, if a single-wave elastic wave, for example, a sine wave is input from the face 17 into the rock 18, the sine wave is reflected by the object to be reflected, and the reflected wave having a constant waveform is converted into the face 1.
7 can be received.

Since the propagation speed of an elastic wave is governed by the elastic coefficient of the rock 18 as a medium, the wavelength differs depending on the physical properties at each position of the rock 18 to be searched. However, the receiving position of the reflected wave is
Since it is the face 17 on the surface of No. 8, it is received as the same wavelength as the input elastic wave.

Even if the waveform is not a wave represented by a periodic function such as a sine wave, if one waveform having clear characteristics is used, the waveform can be prevented from being deformed while propagating through the medium. One such waveform is the solitary wave 30.

In the solitary wave 30, any position x
The wave height η at time t in is obtained by Expression 2.

[0028]

Η = Hsech ² (C ₁ (x−ct)) where η: wave height at position x and time t H: maximum wave height C1: constant c: elastic wave velocity It is infinite and the waveform does not collapse. Also, since the wave has only a single peak, the reflected wave of the transmitted signal naturally has only a single peak. For this reason, when there are a plurality of reflection targets, the number of peaks is received by the number, so that the number of reflection targets can be easily determined.

Also, the time required from the transmission of the solitary wave 30 to the reception of its reflected wave makes it possible to estimate the position of the reflection target to some extent accurately. Further, by comparing the wave heights H of the input solitary wave 30 and its reflected wave 32, the reflection coefficient of the object to be reflected is obtained, and the density and propagation speed of the face rock and the propagation speed of the object to be reflected are assumed. , The density of the reflection target is calculated, and the hardness of the reflection target can be estimated from the density. The reflection coefficient R is
It is defined by the ratio between the amplitude of the incident wave and the amplitude of the reflected wave at the rock boundary surface, and is expressed by Expression 3 using the density ρ ₁ , ρ _{2 of the} rock and the propagation velocities v ₁ , v ₂ .

[0030]

R = (ρ ₂ v ₂ −ρ ₁ v ₁ ) / (ρ ₂ v ₂ + ρ ₁ v ₁ ) According to Equation 3, the solitary wave input from the face rock is reflected from the target object in front of the face. If the characteristic of the reflected wave is positive,
If the bedrock ahead of the face is harder and more negative than the bedrock at the face,
It can be easily determined that the bedrock in front of the face is softer than the bedrock.

Next, the operation of the front face detecting device 10 will be described. When performing a forward search of the face 17, first, a predetermined hydraulic pressure is applied to each of the hydraulic jacks 15A and 15B to apply a preload to the bedrock 18. Thereby, the bedrock 18
The compression force is always applied, and even if many cracks such as joints are formed in the rock 18, the cracks can be prevented from peeling off.
8 can be input efficiently.

At this time, since the rock 18 expands and contracts, the desired solitary wave 30 can be input to the rock 18 by temporally controlling the hydraulic pressure. Then, next, the valve V2 on the detection hydraulic jack 15B side is used.
Is closed and the valve V1 on the input detection hydraulic jack 15A side is closed.
To release. And the solitary wave 3 created by the wave making device 11
0 is supplied to the input detection hydraulic jack 15A via the amplifier 12, the hydraulic pressure conversion device 13, the valve V1, and the pressure converter 16A.

As a result, the solitary wave 30 is converted into a hydraulic pressure and supplied to the input detecting hydraulic jack 15A.
7 is input into the bedrock 18. The hydraulic pressure at this time is determined by the pressure converter 16A, the measuring device 21, the A / D converter 22
The data is supplied to the data recorder 24 via the computer 23.

After the solitary wave 30 is input into the rock 18 in this way, the valve V1 is closed and the input detection hydraulic jack 15A is used for reflected wave detection. If there is an object to be reflected in the rock 18, that is, a fault or a soft crush zone whose physical properties are largely different from those of the rock 18, the solitary wave 30 is reflected by the object to be reflected and returns to the face 17 side. Come.

The reflected wave of the reflected solitary wave 30 is:
It is received by the hydraulic jack for input detection 15A and the hydraulic jack for detection 15B, and is converted into a pressure fluctuation here. This pressure fluctuation is supplied to the data recorder 24 via the pressure converters 16A and 16B, the measuring device 21, the A / D converter 22, and the computer 23, where it is stored for a certain period.

FIG. 3A shows the change over time of the input signal 31, that is, the pressure of the input detection hydraulic jack 15A. In FIG. 3A, the horizontal axis represents time t, and the vertical axis represents the magnitude p of the force.

From the input detection hydraulic jack 15A to the rock 1
8 is applied to the bedrock 18 with a predetermined force in advance.
Is being pressed. This is shown as a linear force increase range 31a on the left side of FIG.

The peak input 31b of large forces at time t ₀ of the signal 31 is an input signal due to solitary wave 30, the force at time t ₁₁ and time t ₁₂ peak 31c, 31
d is a reflected wave from a reflection target object in front of the face 17. That is, the polarity of the reflected wave as well as the elastic wave is reversed depending on the propagation speed and the density of the reflection target as shown in Expression 3. FIG. 3 shows that a rock signal is received as a pressure signal of a hydraulic pressure lower than the preload pressurization level 31a because it is more important to be able to confirm that a soft rock exists in front of the face in rock excavation. .

[0039] Here, the peak force 31c at time t ₁₁ and time t _12, 31d is, the preload of the pressure level 31
a, but this causes a negative pressure change
, But shows a reflected signal. That is, not only the elastic wave but also the reflected wave is received as a pressure signal of a hydraulic pressure lower than the pressurization level 31a of the preload because the polarity is reversed in the positive and negative directions.

FIG. 3B shows a change with time of the received signal, that is, the pressure of the detection hydraulic jack 15B. Here, as in FIG. 3A, a preload 32a is applied to the bedrock 18 in advance. The peak 32c at time t _21, t _22, 32d indicates the received signal of the reflected wave. FIG. 3B does not show a signal corresponding to the peak 31 b of the input signal 31 for the following reason.

That is, the detection hydraulic jack 15B is
Since the face 17 is provided on the same face 17 as the input detection hydraulic jack 15A, when the face 17 is applied by the input detection hydraulic jack 15A, in principle, the force signal is applied in a direction perpendicular to the tunnel axis. Should be measured by the detection hydraulic jack 15B, but since this is very small, it is omitted in FIG. 3 (B).

The wave heights H ₁₁ and H ₁₂ of the peaks 31 c and 31 d at the time of detecting the reflected wave of the input signal 31 shown in FIG.
A peak 32 at the time of detecting a reflected wave of the reception signal 32 shown in FIG.
By comparing the wave heights H ₂₁ and H ₂₂ of c and 32d,
It is possible to estimate the physical properties of the reflection target, that is, the reflection coefficient. From the reflection coefficient and the estimated value of the attenuation rate up to the reflection target, the density, that is, the hardness of the reflection target can be obtained.

The number of reflected wave peaks 32c and 32d
From the number, the number of reflection targets can be obtained. Further
And the signal input time t of the input signal 31₀When receiving reflected waves from
Time t_{1 1}, T₁₂Time t (t₁₁-T₀, T₁₂-T₀) Or
Thus, the distance to the reflection target can be obtained.

Further, the reception time t of the reflected wave of the input signal 31
_11, and t _12, the reflected wave reception time t ₂₁ of the received signal 32, t ₂₂
From the difference Δt (t ₁₁ −t ₂₁ , t ₁₂ −t ₂₂ ), the difference in the distance from each of the hydraulic jacks 15A, 15B to the reflection target can be determined, whereby the direction of the reflection target can be determined.

As described above, in this embodiment, the two hydraulic jacks 15A and 15B are used for detecting the reflected wave, so that the object to be reflected can be detected two-dimensionally. One hydraulic jack can be used for detection. In this case, the reflection target is one-dimensionally captured. Also, three or more hydraulic jacks can be used, and in this case, the reflection target can be captured three-dimensionally.

As described above, according to the face front exploration apparatus 10 and the exploration method using the same according to the present invention, the face 17
Since the solitary wave 30 is used as an elastic wave whose waveform does not collapse when propagating through the front rock 18, the physical properties and position of the reflection target can be accurately determined. Further, when there are a plurality of reflection objects, a plurality of reflected waves can be detected, so that the physical properties and positions of each reflection object can be distinguished and accurately obtained.

Therefore, when excavating the tunnel, the face 17
The range in which the front rock 18 needs to be reinforced and the reinforced method can be determined. For example, when a crushed body or a fault is detected in the bedrock 18, the strength of the bedrock 18 can be improved by injecting a chemical solution or the like. This makes it possible to perform the excavation work reliably and efficiently.

In the above-described embodiment, the solitary wave 30 is used as the elastic wave. However, other elastic waves such as a sine wave having a characteristic that the waveform does not collapse during propagation through the medium, such as a sine wave, may be used. Any waveform can be used. Also,
In the above-described embodiment, the hydraulic jacks 15A and 15B are directly fixed to the face 17 by the anchor 19;
If there is a heavy machine such as a (tunnel boring machine) that can obtain a sufficient reaction force, each of the hydraulic jacks 15A and 15B can be attached thereto. In addition, the present invention can be applied not only to the bedrock in front of the tunnel face described above but also to the ground in front of the shaft face.

[0049]

As described above, according to the method and apparatus for exploring a face in front of a face according to the present invention, an elastic wave whose waveform does not collapse is used when propagating in rock or ground in front of the face. The reflected wave can be reliably detected, whereby the physical properties and position of the reflection target can be accurately obtained. Further, even when there are a plurality of reflection objects, the reflected waves reflected from each reflection object can be clearly distinguished and detected, so that the physical properties and positions of each reflection object can be accurately obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a front face exploration apparatus according to the present invention.

FIG. 2 is a diagram showing a waveform of a solitary wave used in the method for exploring a front face of a face according to the present invention.

FIG. 3 is a diagram showing an input signal and a received signal to the rock according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Face front exploration apparatus 11 Wave making device (wave making means) 15A Hydraulic jack for input detection 15B Hydraulic jack for detection 17 Face 18 Rock rock 30 Solitary wave (elastic wave)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Setsuo Ito 2-10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Inside the Construction Industry Co., Ltd. (72) Inventor Masayuki Mizukawa 2- 10-26, Fujimi 2-chome, Chiyoda-ku, Tokyo F term (reference) in Construction Industry Co., Ltd. 2F068 AA06 CC11 EE02 FF01 FF16 FF25 GG05 KK14 2G047 AA10 BA03 BC02 BC03 GG09 GG19 GG30

Claims (6)

[Claims] 1. An elastic wave having a characteristic that a waveform does not collapse during propagation in a rock or ground is input into the rock or the ground in front of a face, and is reflected from a reflection target in the rock or the ground. A method for exploring a front face of a face, comprising: detecting a reflected wave of the elastic wave; and obtaining a physical property and a position of the reflection target based on the detected reflected wave. 2. The method according to claim 1, wherein the elastic wave is a solitary wave or a sine wave. 3. A wave generating means for generating an elastic wave whose waveform does not collapse during propagation in a rock or ground; an elastic wave input means for inputting the elastic wave into the rock or the ground in front of a face; Reflected wave detecting means for detecting a reflected wave of the elastic wave reflected by a rock or a reflection target in the ground,
A front face exploration device comprising: 4. The elastic wave input means and the reflected wave detection means are hydraulic jacks.
3. The front face exploration device according to 1. 5. The front face exploration apparatus according to claim 4, wherein a preload is applied to the face face from the hydraulic jack. 6. The apparatus according to claim 3, wherein a plurality of the reflected wave detecting means are provided.