Deep horizontal displacement monitoring device based on fiber bragg grating

Abstract

The utility model relates to a deep layer horizontal displacement monitoring device based on a fiber bragg grating, which comprises a sensor protection cylinder and a protection pipe, a flame-retardant corrugated pipe is fixedly sleeved outside the sensor protection cylinder, and the other end of the flame-retardant corrugated pipe is connected with a counterweight guide head; a pull rod is slidably arranged in the protective tube, and the outer end of the pull rod is fixedly connected with the inner end of a counterweight guide head through a steel wire rope; a fiber bragg grating is arranged in the sensor protection cylinder, a fixing base is arranged at the rear end of the sensor protection cylinder, the rear end of the fiber bragg grating is fixedly connected with the fixing base, the inner end of the pull rod is connected with the front end of the fiber bragg grating through a spring, and the sensor protection cylinder is filled with stemming. And the fiber grating displacement meter placed in the drill hole can be protected.

Description

Technical Field

[0001] The utility model relates to a deep horizontal displacement monitoring device based on optical fiber grating, belonging to the technical field of measurement. Background Art

[0002] Fiber Bragg grating displacement meters are used to measure concrete cracks, structural joints, deformation displacement, etc. They can also monitor ground fissures, ground subsidence and deep displacement of surrounding rock masses.

[0003] However, the characteristics of the optical fiber itself, such as its thin aperture, brittle texture, and easy breakage, limit the widespread application of fiber Bragg grating technology. For example, CN111537119A discloses a high-precision fiber Bragg grating displacement meter with temperature compensation, including a sensitive component, a spring, and a probe rod, which are connected in sequence on the same central axis. The sensitive component includes a fiber base, a strain measurement fiber Bragg grating, and a temperature measurement fiber Bragg grating, and the strain measurement fiber Bragg grating and the temperature measurement fiber Bragg grating are both arranged on the fiber base. The sensitive component and the spring are on the same central axis, and there are fewer factors affecting the measurement process. The sensor repeatability and hysteresis error are small, and the linear fitting accuracy is high. However, the device directly exposes the displacement meter to the outside. When it is necessary to lower the borehole for monitoring, the surface of the displacement meter is in direct contact with the borehole, which can easily cause damage to the displacement meter. Utility Model Content

[0004] In order to solve the above problems existing in the prior art, the utility model provides a deep horizontal displacement monitoring device based on fiber grating, which can protect the fiber grating displacement meter placed in the borehole.

[0005] The technical solution of the utility model is as follows:

[0006] A deep horizontal displacement monitoring device based on fiber grating includes a sensor protection tube and a protective tube, wherein the outer fixed sleeve of the sensor protection tube is provided with a flame-retardant corrugated tube, and the other end of the flame-retardant corrugated tube is connected to a counterweight guide head; a pull rod is slidably arranged inside the protective tube, and the outer end of the pull rod is fixedly connected to the inner end of the counterweight guide head through a steel wire rope; a fiber grating is arranged inside the sensor protection tube, and a fixed base is arranged at the rear end of the sensor protection tube, and the rear end of the fiber grating is fixedly connected to the fixed base, and the inner end of the pull rod is connected to the front end of the fiber grating through a spring, and the interior of the sensor protection tube is filled with cannon mud.

[0007] Wherein, a pigtail is fixed at one end of the fiber grating.

[0008] Wherein, the pigtail is protected by an armored optical cable.

[0009] Wherein, the front end of the fiber grating is connected to the spring through a connecting piece.

[0010] Wherein, the fiber grating is located on the axis and is on the same central axis as the spring and the pull rod.

[0011] The utility model has the following beneficial effects:

[0012] The utility model provides a certain rigidity for the device through the flame-retardant corrugated tube, and fills the interior of the sensor protection tube with gun mud, which provides a space for the fiber optic Bragg grating to allow movement while also protecting the fiber optic Bragg grating; different from other displacement meter installation methods that directly expose the line in the borehole, the survival rate of the displacement meter is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0014] Figure 2 This is a schematic diagram of the internal structure of the sensor protection cylinder and protection tube of the utility model.

[0015] The reference numerals in the figure represent:

[0016] 1. Sensor protection tube; 2. Protective tube; 3. Flame retardant corrugated tube; 4. Counterweight guide head; 5. Pull rod; 6. Wire rope; 7. Fiber Bragg grating; 8. Connector; 9. Pigtail; 10. Armored optical cable; 11. Universal shaft. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] See also Figure 1 to Figure 2 , the utility model provides a technical solution:

[0019] A deep horizontal displacement monitoring device based on fiber grating includes a sensor protection tube 1 and a protective tube 2. A flame retardant corrugated tube 3 is fixedly sleeved outside the sensor protection tube 1. The sensor protection tube 1 and the protective tube 2 are sealed and protected by the flame retardant corrugated tube 3, and a counterweight guide head 4 is connected to the other end of the flame retardant corrugated tube 3. When the device is assembled, the assembled device is lowered into a borehole. Under the action of the gravity of the counterweight guide head 4, the device is sent into the borehole, and a grouting pipe is lowered at the same time.

[0020] A pull rod 5 is slidably arranged inside the protective tube 2, and the outer end of the pull rod 5 is fixedly connected to the inner end of the counterweight guide head 4 through a steel wire rope 6; a fiber grating 7 is arranged inside the sensor protective tube 1, and a fixed base is arranged at the rear end of the sensor protective tube 1, and the rear end of the fiber grating 7 is fixedly connected to the fixed base, the inner end of the pull rod 5 is connected to the front end of the fiber grating 7 through a spring, and the front end of the fiber grating 7 is connected to the spring through a connecting piece 8, and the interior of the sensor protective tube 1 is filled with gun mud.

[0021] Since the device is placed vertically into the drill hole, the front end counterweight guide head 4 and the end head of the device are respectively installed on two objects to be measured with relative displacement. The displacement to be measured is converted into the relative displacement between the pull rod 5 and the connecting member 8, that is, the expansion and contraction of the spring, which is also converted into the change of the tension applied by the spring on the connecting member 8, thereby stretching or compressing the fiber grating 7, thereby causing the reflection wavelength of the fiber grating 7 to move. By detecting the movement of the reflection wavelength of the fiber grating 7, the change information of the displacement to be measured can be detected.

[0022] A pigtail 9 is fixed to one end of the fiber grating 7 . The pigtail 9 is protected by an armored optical cable 10 . The fiber grating 7 is located on the axis and is on the same central axis as the spring and the pull rod 5 .

[0023] The sensor protection tube 1 is a thickened steel tube.

[0024] As a preferred embodiment, the steel wire rope 6 is fixedly connected to the inner end of the counterweight guide head 4 via a universal shaft 11; in the case of grouting, the contact between the mud and the counterweight guide head 4 may cause the counterweight guide head 4 to be offset. Under the action of the universal shaft 11, the rotation of the counterweight guide head 4 will not affect the internal components.

[0025] The working principle of the above-mentioned deep horizontal displacement monitoring device based on fiber grating is as follows:

[0026] First, a hole is drilled; then the device is lowered, the assembled device is placed inside the borehole, and under the gravity of the counterweight guide head 4, it is sent into the hole, and a grouting pipe is lowered at the same time; finally, the borehole is backfilled through the grouting pipe.

[0027] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A deep horizontal displacement monitoring device based on fiber grating, comprising a sensor protection tube (1) and a protection tube (2), characterized in that: The sensor protection tube (1) is provided with a flame-retardant corrugated tube (3) on the outside of the fixed sleeve, and the other end of the flame-retardant corrugated tube (3) is connected to a counterweight guide head (4); a pull rod (5) is slidably arranged inside the protection tube (2), and the outer end of the pull rod (5) is fixedly connected to the inner end of the counterweight guide head (4) through a steel wire rope (6); a fiber optic Bragg grating (7) is arranged inside the sensor protection tube (1), and a fixed base is arranged at the rear end of the sensor protection tube (1), and the rear end of the fiber optic Bragg grating (7) is fixedly connected to the fixed base, and the inner end of the pull rod (5) is connected to the front end of the fiber optic Bragg grating (7) through a spring, and the interior of the sensor protection tube (1) is filled with gun mud.

2. The deep horizontal displacement monitoring device based on fiber grating as claimed in claim 1, characterized in that: A pigtail (9) is fixed at one end of the optical fiber grating (7).

3. A deep horizontal displacement monitoring device based on fiber grating as claimed in claim 2, characterized in that: The pigtail (9) is protected by an armored optical cable (10).

4. The deep horizontal displacement monitoring device based on fiber grating as claimed in claim 1, characterized in that: The front end of the optical fiber grating (7) is connected to the spring via a connecting piece (8).

5. The deep horizontal displacement monitoring device based on fiber grating as claimed in claim 1, characterized in that: The optical fiber grating (7) is located on the axis and is on the same central axis as the spring and the pull rod (5).

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