JP2003293682A - Method and device for detecting ground sink in element towing and propelling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for detecting a ground sink beforehand in an element towing and propelling method such as a pipe roofing method. <P>SOLUTION: Flexible tubes are installed under the ground in a direction crossing the center axies of the tubes inserted into the ground. Optical fiber strain sensors are fitted to the flexible tubes integrally with each other so that the ground sink can be detected by signals from the optical fiber strain sensors obtained through the strain of the flexible tubes. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for detecting ground depression in an element towing and propulsion method represented by a pipe roof method.

[0002]

2. Description of the Related Art As shown in FIG. 6, as a construction method for traversing under a railroad or a road, a rectangular tubular concrete box a or the like is towed from the opposite side to construct a structure traversing under the railway. Method is used. When such a concrete box a is traversed, there is a possibility that the ground of a railway or a road may be depressed. Therefore, prior to the step of towing the concrete box a, a large number of pipes b are first towed and propelled into the ground to be installed side by side to construct vertical and horizontal supports by the pipe b group. Element towing represented by, and auxiliary work called propulsion method is being performed.

[0003]

The above-described element towing and propulsion methods represented by the pipe roof method have the following problems. <B> Cavities are likely to occur at the joints between pipes due to over-digging. <B> Due to the presence of this cavity, there is a case where the earth and sand above moves abruptly downward and the ground surface sinks, despite the fact that the surroundings of the structure are protected by the pipe roof. <C> From past cases, it is known that this depression has a depression surface F in a range of 45 degrees from the center of the second pipe from the uppermost stage of the pipe installed in the vertical direction. <D> In order to detect the occurrence of such depressions, 24-hour monitoring by surveillance staff and automatic surveying using a reflector are performed, but there is a possibility that anomalies on the ground surface may be overlooked when there is snow. However, there is a problem that it cannot be confirmed until the depression phenomenon appears on the ground surface.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and can detect the depression of the ground in advance in the element towing and propulsion methods represented by the pipe roof method. It is an object of the present invention to provide a possible method and a detecting device.

[0005]

In order to achieve the above-mentioned objects, the method of detecting ground depression in the element towing and propulsion method of the present invention is to provide a ground around a structure when constructing an underground structure. Element towing to prevent the depression of the ground by inserting a pipe inside, a method of detecting the depression of the ground in the propulsion method, in which a flexible pipe is installed in a direction transverse to the central axis of the pipe inserted into the ground. Installed in the ground, an optical fiber strain sensor is integrally attached to this flexible pipe, and the depression of the ground is detected by the signal of the optical fiber strain sensor obtained through the strain of the flexible pipe, It features a method of detecting ground depression.

Further, the detection device of the present invention is an element towing for preventing a sinking of the ground by inserting a pipe into the ground around the structure when constructing an underground structure, and detecting a sinking of the ground used in a propulsion method. The device comprises a flexible pipe installed in the ground in a direction transverse to the central axis of the pipe inserted into the ground, and an optical fiber strain sensor installed integrally with the flexible pipe. It is characterized by a ground depression detection device.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a ground depression detection method and a detection device in the element towing and propulsion construction method of the present invention will be described below with reference to the drawings by taking a pipe roof construction method as an example.

<A> Structure of the sensor 1. First, the sensor 1 used for detecting the depression of the ground of the present invention
The structure of will be described. The sensor 1 includes a flexible tube 11 and an optical fiber strain sensor 12 installed integrally with the flexible tube 11. As the flexible pipe 11, for example, a commercially available PVC pipe can be used.

<B> Optical fiber strain sensor 12. On the other hand, as the optical fiber strain sensor 12, a commercially available FBG sensor is used. This optical fiber strain sensor 12
Sends a broadband optical signal to the optical fiber 121, reflects it from the optical fiber strain sensor 12, and
The first FBG 1 receives the optical signal returned via the
Strain of 22 parts and 2nd FBG122 part is measured and performed. A measuring device for measuring the strain is connected to one end of the optical fiber 121, transmits a broadband optical signal, and measures the Bragg wavelength returned from the optical fiber 121. In the example shown in the figure, a plurality of FBGs 122 are arranged in one optical fiber, and a broadband transmission light spectrum is transmitted to the optical fiber 121.
The reflected light spectrum sent out and returned through the optical fiber 121 is used for the first FBG 122 and the second FBG of each sensor unit.
It includes a pair of Bragg wavelengths from BG122. When a plurality of sensor parts are arranged in series in one optical fiber 121, the FGB parts are identified by making the Bragg wavelengths different. In this way, the optical fiber 121 provided with the FBG portion 122 at one or more places is attached to the flexible tube 11. This mounting method is performed by, for example, carving a groove on the outer surface of the pipe 11 in a direction parallel to the central axis of the pipe 11,
The optical fiber strain sensor 12 can be housed in this groove and bonded. The outer circumference of the flexible tube 11 is covered with a protective tube 13 to protect the optical fiber 121 housed in the groove.

<C> Construction of a pipe roof. Prior to the construction of the structure, a large number of pipes 2 are inserted on the upper surface and side surfaces of the planned construction area. This pipe roof construction method is a known construction method, and a large number of pipes 2 are inserted side by side in a row in the horizontal direction in a state like a roof on the upper surface of the planned construction range. On the side of the construction area, like a wall,
A large number of pipes 2 are arranged in a line in the vertical direction and inserted.
The pipe 2 has a diameter of, for example, about 80 cm, and can be put inside by a person.

<D> The opening of the pipe 2. Among the pipes 2 installed in the ground by the pipe roof construction method, a small cross-section hole is opened on the side surface of the pipe 2 arranged at the corner where the horizontal pipe group 2 and the vertical pipe group 2 intersect. A protective cylinder 3 facing the ground is installed in this opening. This protection tube 3
It is a short cylinder with a collar, and presses into it while discharging the earth and sand to protect the surroundings of the opening.

<H> Bowling. From this opening, a sensor installation hole 31 is opened in a direction orthogonal to the central axis of the pipe 2. Therefore, a casing is installed and boring is performed. The diameter of this casing is set to an inner diameter slightly larger than the outer diameter of the sensor 1.

<F> Insertion of the sensor 1. When the casing is gently removed, the sensor installation hole 31 remains in the ground. The sensor 1 described above, that is, the sensor 1 in which the optical fiber strain sensor 12 is attached to the flexible tube 11 is inserted into the sensor installation hole 31.
Further, inside the flexible pipe 11, there is a filling pipe 14 for filling material.
Install a hose. The end of the flexible tube 11 is a padding 1
5, and only the tip of the injection hose 14 is exposed to the outside of the tip filling 15. Protective tube 3 and sensor 1
The mouth filling material 32 is arranged in the space between the two, and the end of the flexible tube 11 is exposed to the pipe 2 side with respect to the mouth filling material 32, and the wiring of the optical fiber 121 and the filling hose 14 are provided inside the pipe 2. Pull out to. The mouth-filling material 32 is made of an elastic material so as not to firmly fix the sensor 1 and the pipe 2 side.

<G> Sensor installation position. As described above, the sensor 1 is installed in a direction crossing the central axis of the pipe 2. In particular, the sensor 1 is installed at or near a position where the sensor 1 crosses the estimated depression surface F of the ground.
By installing the flexible tube 11 at a position that crosses the depression surface F, the flexible tube 11 can be provided at an initial stage of depression.
Can be distorted. The estimated depression surface F can be inferred from past depression examples as described above.

<H> Filling. The filling material 33 is injected between the flexible pipe 11 and the ground through the filling hose 14 arranged inside the flexible pipe 11. As the filler 33, one having the same strength as the material of the natural ground is used. By this injection, the space between the flexible pipe 11 and the sensor installation hole 31 is filled, and the flexible pipe 11 directly receives the behavior of the natural ground. After that, the hose 14 is cut, and the lid plate is attached to the inside of the protective cylinder 3. The optical fiber 121 is pulled out from the lid plate into the pipe 2 and connected to the transmission optical fiber 123.

<R> Detection circuit. (FIG. 4) The pull-out side of the transmission optical fiber 123 is connected to a control PC or a monitoring PC installed outside the pipe 2. P for monitoring
C can issue various alarms when an abnormality occurs.
Commercially available or publicly known systems, circuits, and devices can be used.

<N> Detection method. (Fig. 5) Before the depression occurs, the movement of soil occurs in the ground with the estimated depression surface F as a boundary. In the sensor 1 of the present case, since the flexible pipe 11 is installed in the ground at a position crossing the estimated depression surface F, the flexible pipe 11 is distorted by the movement of soil. The strain of the flexible tube 11 is detected as a strain amount by the optical fiber strain sensor 12. This distortion amount is
It is saved in the distortion save file and is compared with the distortion amount immediately before calling (minutes, hours, days) from the file. As a result of comparison, when the amount exceeds a certain control value, it is determined that there is an abnormality, and various alarms are issued, such as calling the mobile phone of the person in charge.

[0018]

As described above, the ground depression detection method and detection device in the element towing and propulsion construction method of the present invention are as described above, and the following effects can be obtained. <B> It is possible to detect the movement in the natural ground before the depression.
Therefore, appropriate countermeasures can be taken on the ground surface before the occurrence of depression. <B> Higher accuracy compared to the visual control by the observer,
No oversight will occur in the event of rain or snow. <C> Although the pipe roof construction method has been described above as an example, it can be used for other construction methods called element towing and element propulsion construction methods.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a ground depression detection method according to the present invention.

FIG. 2 is an explanatory diagram of an embodiment of an apparatus used for detection.

FIG. 3 is an explanatory view of a state in which the detection device is installed on a pipe.

FIG. 4 is an explanatory diagram of an embodiment of a detection circuit.

FIG. 5 is an explanatory diagram of an embodiment of a detection method.

FIG. 6 is an explanatory diagram of a situation of occurrence of depression.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoichi Furuyama             14-22 Minamiishikiri-cho, Wakabayashi-ku, Sendai City, Miyagi Prefecture (72) Inventor Takeshi Ito             27-134 Yosegi, Matsuo Village, Iwate District, Iwate Prefecture (72) Inventor Ryuichi Hatsugai             Iwate Prefecture Isawa-gun Maesawa Town Maternal character 1-40 Futako (72) Inventor Hiroshi Shiomi             2-3-8 Ninomiya, Tsukuba City, Ibaraki Prefecture (72) Inventor Toshio Ogasawara             1-15-1 Hatagocho, Yamagata City, Yamagata Prefecture (72) Inventor Wataru Kurahashi             1-17-19 Higashifujisawa, Iruma City, Saitama Prefecture (72) Inventor Tomio Fujikawa             3-13-25-Miyamaedaira, Miyamae-ku, Kawasaki City, Kanagawa Prefecture             402 F term (reference) 2D054 AC15 GA15 GA82                 2F051 AA06 AB03 BA07                 2F076 BA18 BB09 BD06 BD17 BE01                       BE04 BE05 BE15 BE17                 2F103 CA04 CA07 EC09 GA14 GA15

Claims (6)

[Claims] 1. A method for detecting a ground depression in an element towing and a propulsion method, wherein a pipe is inserted into the ground around the structure to prevent the depression of the ground when constructing an underground structure. A flexible pipe is installed in the ground in a direction transverse to the central axis of the inserted pipe, and an optical fiber strain sensor is integrally attached to this flexible pipe. A ground depression detection method that detects ground depression based on the signal from an optical fiber strain sensor obtained through strain. 2. A method for detecting a ground depression in an element towing and a propulsion method, wherein a pipe is inserted into the ground around the structure to prevent the depression of the ground when constructing the underground structure. A flexible pipe is installed in the ground in a direction crossing the central axis of the inserted pipe and at a position crossing the estimated depression surface of the ground, and an optical fiber strain sensor is integrated into this flexible pipe. The method for detecting ground depression is to detect the depression of the ground by the signal of the optical fiber strain sensor that is obtained through the strain of the flexible pipe. 3. An element towing for preventing a depression of the ground by inserting a pipe into the ground around the structure when constructing an underground structure, and a method of detecting a ground depression in a propulsion method, which comprises: Drill a hole in the direction that crosses the center axis of the inserted pipe and a position that crosses the estimated depression surface of the ground, and install a flexible pipe inside it. Is equipped with a fiber optic strain sensor as an integral unit. By filling the space between the flexible pipe and the ground with a filler and transmitting the movement of the ground to the flexible pipe, the strain of the flexible pipe is A method of detecting ground depression, which detects ground depression based on the signal from the optical fiber strain sensor obtained through. 4. An element towing for preventing a sinking of the ground by inserting a pipe into the ground around the structure when constructing an underground structure, and a method for detecting a ground sinking in a propulsion method, comprising: Drill a hole in the direction that crosses the center axis of the inserted pipe and a position that crosses the estimated depression surface of the ground, and install a flexible pipe inside it. Is equipped with an optical fiber strain sensor integrally, and a space between the flexible pipe and the ground is filled with a filling material, and a cushioning material is connected to the flexible pipe and the pipe inserted into the ground. A ground depression detection method that detects the depression of the ground by the signal of the optical fiber strain sensor obtained through the strain of the flexible pipe by transmitting the movement of the ground to the flexible pipe through the connection. . 5. A ground subsidence detection device for use in a pipe roof construction method for preventing a subsidence of the ground by inserting a pipe into the ground around the substructure at the time of constructing an underground structure. A ground depression detecting device comprising a flexible pipe installed in the ground in a direction crossing the central axis of the pipe to be inserted, and an optical fiber strain sensor installed integrally with the flexible pipe. 6. A ground depression detecting device for use in a pipe roof construction method, wherein a pipe is inserted into the ground around a structure to prevent the depression of the ground when constructing an underground structure. A flexible pipe installed in the ground in a direction crossing the central axis of the pipe to be inserted and at a position crossing the estimated depression surface of the ground, and an optical fiber strain installed integrally with this flexible pipe. Ground depression detection device composed of a sensor.