Rock state monitoring device based on optical fiber sensing technology

Abstract

The utility model discloses a surrounding rock state monitoring device based on optical fiber sensing technology relates to surrounding rock strain monitoring technical field, including hollow anchor rod, steel pipe, fixed in hollow anchor rod inner wall, its outer wall has established at least one arc -shaped recess with the cooperation of the guide groove and the protruding of the setting, and the recess extends along the steel pipe axial direction, the utility model has the beneficial effects that: through the cooperation of the guide groove and the protruding of the setting, makes the optical fiber sensor form composite space form and produce multi -region even contact with the protruding, has realized hollow anchor rod multidimensional complex deformation and the accurate coupling of optical fiber sensor strain signal, has broken through the limitation that traditional linear optical fiber is not enough to bending, shear and other deformation perception sensitivity, has promoted the accuracy of surrounding rock failure mechanism judgement, and through the dispersed contact part has avoided the local stress concentration of optical fiber sensor, has reduced the risk of bending, debonding, has reduced signal noise and transmission loss, has enhanced the stability and reliability of long -term monitoring significantly.

Description

Technical Field

[0001] This utility model relates to the field of surrounding rock strain monitoring technology, specifically a surrounding rock condition monitoring device based on fiber optic sensing technology. Background Technology

[0002] As underground engineering extends into deeper and more complex geological conditions, higher demands are placed on the real-time and accurate monitoring of surrounding rock stability. Monitoring devices based on fiber optic sensing technology have become an important means of safety monitoring in geotechnical engineering due to their strong anti-interference capabilities and ability to perform distributed measurements. Among these methods, combining sensing fibers with support anchors to form intelligent sensing anchors is an effective way to monitor deep deformation and in-situ stress in the surrounding rock. Currently, common techniques often involve attaching the fiber optic cable in a straight line to the surface of the anchor or placing it inside its hollow cavity. While this direct and simple deployment method can achieve basic strain transmission, its monitoring performance in complex geotechnical environments remains significantly limited.

[0003] The main problem with existing technologies is that the contact form between linearly deployed optical fibers and anchor structures is singular, and the effective contact area is limited. This leads to two prominent issues: First, the multidimensional and complex deformations (such as bending, shearing, and torsion) generated when the anchor is actually under stress are difficult to couple efficiently and convert into axial strain that can be accurately measured by the optical fiber, resulting in insufficient sensitivity to key deformation modes and blurred signal characteristics, which in turn affects the accurate judgment of the surrounding rock failure mechanism; Second, under continuous deformation or dynamic disturbance of the surrounding rock, the optical fiber is prone to slippage or even debonding due to local stress concentration, introducing significant signal noise and transmission loss, which seriously affects the stability and reliability of long-term monitoring.

[0004] Therefore, a novel fiber optic anchor structure needs to be designed to optimize the mechanical transmission path and improve the ability to sense complex deformations and signal quality. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model provides a surrounding rock condition monitoring device based on fiber optic sensing technology.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows:

[0007] A surrounding rock condition monitoring device based on fiber optic sensing technology, including hollow anchor bolts;

[0008] A steel pipe is fixed to the inner wall of the hollow anchor rod. At least one arc-shaped groove is formed on the outer wall of the pipe in the circumferential direction. The groove extends axially along the steel pipe. An arc-shaped flexible pad is fitted inside the groove. A guide groove is formed axially on the arc surface of the flexible pad. The extension path of the guide groove satisfies the following two geometric constraints: first, it extends in a periodic curve in a direction parallel to the axis of the steel pipe; second, the distance between the bottom of the groove and the inner wall of the hollow anchor rod on a cross section perpendicular to the axis of the steel pipe varies periodically.

[0009] Multiple fiber optic sensors are embedded in the corresponding guide grooves;

[0010] Multiple arc-shaped protrusions are respectively provided on the inner wall of the hollow anchor rod at the position corresponding to the flexible liner. The protrusions are pressed into the flexible liner and the two abut against each other.

[0011] The fiber optic sensor, influenced by the guide groove path, forms a composite spatial shape with axial wave undulation and radial fluctuation within its cavity; this shape causes multiple contact points to be uniformly distributed in the length and height directions between the fiber optic sensor and the inner surface of the protrusion.

[0012] Preferably, the arc surface of the protrusion has the same curvature as the arc surface of the flexible pad, so that the two can completely surround the fiber optic sensor after they are fastened together.

[0013] Preferably, the trajectory of the guide groove is either a sinusoidal waveform trajectory or a continuous S-shaped periodic wave trajectory.

[0014] Preferably, the number of the grooves is four, and they are evenly distributed along the circumference of the steel pipe.

[0015] Preferably, the guide groove is filled with flexible potting compound, and the fiber optic sensor is encapsulated and positioned therein.

[0016] Preferably, a control box is provided at the end of the hollow anchor rod, and the pigtails of multiple optical fiber sensors are electrically connected to the same protective optical cable. The protective optical cable is provided with an optical cable plug and is electrically connected to the control box through the optical cable plug.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows: by cooperating with the guide groove and the protrusion, the fiber optic sensor forms a composite spatial shape and makes uniform contact with the protrusion in multiple areas. This not only realizes the precise coupling between the multi-dimensional complex deformation of the hollow anchor and the strain signal of the fiber optic sensor, but also breaks through the limitation of insufficient sensitivity of traditional straight optical fibers to deformations such as bending and shearing, and improves the accuracy of judging the failure mechanism of the surrounding rock. Furthermore, by dispersing the contact parts, it avoids local stress concentration of the fiber optic sensor, reduces the risk of bending and debonding, reduces signal noise and transmission loss, and significantly enhances the stability and reliability of long-term monitoring. Attached Figure Description

[0018] The disclosure of this utility model is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:

[0019] Figure 1 This is a schematic diagram of the structure of this utility model;

[0020] Figure 2 This is a cross-sectional view of the present invention;

[0021] Figure 3 for Figure 2 A magnified structural diagram of part A in the middle;

[0022] Figure 4 This is a partial exploded view of the present invention;

[0023] Figure 5 This is a schematic diagram of the guide groove in this utility model.

[0024] The diagram is labeled as follows: 1. Hollow anchor rod; 2. Steel pipe; 21. Groove; 22. Flexible gasket; 221. Guide groove; 3. Fiber optic sensor; 4. Protrusion; 5. Control box. Detailed Implementation

[0025] It is readily understood that, based on the technical solution of this utility model, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of this utility model. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative descriptions of the technical solution of this utility model and should not be considered as the entirety of this utility model or as limitations or restrictions on the technical solution of this utility model.

[0026] Example

[0027] like Figures 1-5 As shown, the surrounding rock condition monitoring device based on fiber optic sensing technology includes a hollow anchor bolt 1. The main load-bearing structure of the device is not only a key component of the surrounding rock support, but also the installation carrier for all monitoring components, providing a stable installation benchmark and protective shell for the monitoring system.

[0028] The steel pipe 2 is fixed to the inner wall of the hollow anchor rod 1. At least one arc-shaped groove 21 is opened on its outer wall along the circumference. There are four grooves 21, which are equidistantly distributed along the circumference of the steel pipe 2. The grooves 21 extend along the axial direction of the steel pipe 2. The surrounding design of multiple grooves 21 realizes the orderly installation of the fiber optic sensor 3, avoiding the multiple fiber optic sensors 3 from getting tangled or shifting in position. At the same time, the equidistant circumferential distribution layout ensures the comprehensiveness of monitoring, can capture deformation information of the surrounding rock in different directions, and improves the integrity of monitoring data.

[0029] An arc-shaped flexible pad 22 is fitted inside the groove 21; a guide groove 221 is axially formed on the arc surface of the flexible pad 22, and the extension path of the guide groove 221 satisfies the following two geometric constraints: first, it extends in a periodic curve in the direction parallel to the axis of the steel pipe 2, and the trajectory of the guide groove 221 is either a sinusoidal waveform trajectory or a continuous S-shaped periodic wave trajectory; second, the distance between the bottom of the groove and the inner wall of the hollow anchor rod 1 on the cross section perpendicular to the axis of the steel pipe 2 varies periodically. Through the special curve design of the guide groove 221, on the one hand, the contact area between the fiber optic sensor 3 and the hollow anchor rod 1 in the width direction is increased; on the other hand, since the fiber optic sensor 3 is distributed on the arc surface of the flexible pad 22, the periodically changing groove bottom spacing (perpendicular to the axis of the steel pipe 2) increases the contact area between the fiber optic sensor 3 and the hollow anchor rod 1 in the thickness direction.

[0030] Multiple fiber optic sensors 3 are embedded in corresponding guide grooves 221. The guide grooves 221 are filled with flexible potting compound, which covers and positions the fiber optic sensors 3. This achieves stable positioning of the fiber optic sensors 3, preventing displacement due to vibration or deformation of the surrounding rock during monitoring, while also maintaining a certain degree of flexibility so as not to affect the slight deformation of the fiber optic sensors 3 caused by the deformation of the surrounding rock. At the same time, it also plays a role in sealing, moisture-proofing, and corrosion protection, extending the service life of the fiber optic sensors 3 in underground humid and complex environments.

[0031] Multiple arc-shaped protrusions 4 are respectively located on the inner wall of the hollow anchor rod 1 at positions corresponding to the flexible pad 22. The protrusions 4 are pressed into the flexible pad 22 and abut against each other. The arc surface of the protrusions 4 and the arc surface of the flexible pad 22 are consistent, so that they can completely surround the fiber optic sensor 3 after they are engaged. The arc surface fitting design of the protrusions 4 ensures close contact between the protrusions 4 and the flexible pad 22, so that the fiber optic sensor 3 is completely wrapped, further improving the positioning stability. At the same time, the pressing action of the protrusions 4 causes the fiber optic sensor 3 to form multiple uniformly distributed contact points (in the length and height directions) with the flexible pad 22 and the inner surface of the protrusions 4. These contact points can synchronously transmit deformation information at different positions, avoid excessive local stress on the fiber optic sensor 3, and improve the uniformity and accuracy of the monitoring data.

[0032] The hollow anchor bolt 1 has a control box 5 at its end, which contains an electrically connected fiber optic demodulator, a wireless data transmitter, and a miniature power supply (none of which are shown in the text). The fiber optic demodulator converts the optical signal transmitted by the fiber optic sensor 3 into a resolvable electrical signal; the wireless data transmitter remotely transmits the processed monitoring data to the back-end system; and the miniature power supply provides continuous power to the entire monitoring system. The pigtails of multiple fiber optic sensors 3 are electrically connected to the same protective optical cable. The protective optical cable is equipped with an optical cable plug and is electrically connected to the control box 5 through the optical cable plug. The protective optical cable avoids the pigtails being directly exposed to the complex environment, preventing them from being pulled, worn, or corroded. The design of the optical cable plug enables a modular connection between the fiber optic sensor 3 and the control box 5, facilitating installation and connection.

[0033] The fiber optic sensor 3 is affected by the path of the guide groove 221, forming a composite spatial shape with axial wave undulation and radial fluctuation in its cavity; this shape causes multiple contact points to be uniformly distributed in the length and height directions between the fiber optic sensor 3 and the inner surface of the protrusion 4.

[0034] In summary, by creating a guide groove 221 with a special trajectory on the arc surface of the flexible pad 22, the fiber optic sensor 3 forms a composite spatial shape with axial wave undulation and radial fluctuation. On the one hand, compared with the single contact form between the straight fiber and the anchor in the prior art, the composite spatial shape causes the fiber optic sensor 3 to form multiple contact points that are uniformly distributed in length and height directions between the inner surface of the arc-shaped protrusion 4. This can synchronously couple the multi-dimensional complex deformations such as bending, shearing, and torsion generated by the hollow anchor 1 under force and convert them into strain signals that can be accurately measured by the fiber optic, effectively improving the sensitivity to key deformation forms and solving the problems of ambiguous signal characteristics and difficulty in accurately judging the failure mechanism of the surrounding rock in the prior art. On the other hand, the uniformly distributed contact points can distribute the force generated by the deformation of the surrounding rock or dynamic disturbance to multiple areas of the fiber optic sensor 3, avoiding local stress concentration, fundamentally reducing the risk of fiber slippage and debonding, reducing signal noise and transmission loss, significantly improving the stability and reliability of long-term monitoring, optimizing the optical transmission path, and ultimately achieving efficient perception and high-quality signal acquisition of complex surrounding rock deformation.

[0035] The technical scope of this utility model is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this utility model, and all such modifications and variations should fall within the protection scope of this utility model.

Claims

1. A surrounding rock condition monitoring device based on fiber optic sensing technology, comprising a hollow anchor bolt, characterized in that: A steel pipe is fixed to the inner wall of the hollow anchor rod. At least one arc-shaped groove is formed on the outer wall of the pipe in the circumferential direction. The groove extends axially along the steel pipe. An arc-shaped flexible pad is fitted inside the groove. A guide groove is formed axially on the arc surface of the flexible pad. The extension path of the guide groove satisfies the following two geometric constraints: first, it extends in a periodic curve in a direction parallel to the axis of the steel pipe; second, the distance between the bottom of the groove and the inner wall of the hollow anchor rod on a cross section perpendicular to the axis of the steel pipe varies periodically. Multiple fiber optic sensors are embedded in the corresponding guide grooves; Multiple arc-shaped protrusions are respectively provided on the inner wall of the hollow anchor rod at the position corresponding to the flexible liner. The protrusions are pressed into the flexible liner and the two abut against each other. The fiber optic sensor, influenced by the guide groove path, forms a composite spatial shape with axial wave undulation and radial fluctuation within its cavity; this shape causes multiple contact points to be uniformly distributed in the length and height directions between the fiber optic sensor and the inner surface of the protrusion.

2. The surrounding rock condition monitoring device based on fiber optic sensing technology according to claim 1, characterized in that: The raised arc surface has the same curvature as the flexible pad, so that when the two are fastened together, they can completely surround the fiber optic sensor.

3. The surrounding rock condition monitoring device based on fiber optic sensing technology according to claim 2, characterized in that: The trajectory of the guide groove is either a sinusoidal waveform or a continuous S-shaped periodic wave trajectory.

4. The surrounding rock condition monitoring device based on fiber optic sensing technology according to claim 1, characterized in that: The number of the grooves is four, and they are evenly distributed along the circumference of the steel pipe.

5. The surrounding rock condition monitoring device based on fiber optic sensing technology according to claim 1, characterized in that: The guide groove is filled with flexible potting compound, and the fiber optic sensor is encapsulated and positioned within it.

6. The surrounding rock condition monitoring device based on fiber optic sensing technology according to claim 1, characterized in that: The hollow anchor rod is equipped with a control box at its end. The pigtails of multiple optical fiber sensors are electrically connected to the same protective optical cable. The protective optical cable is equipped with an optical cable plug and is electrically connected to the control box through the optical cable plug.

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