Optical fiber monitoring device for full-length grouting prestressed hollow anchor rod

Abstract

The optical fiber monitoring device comprises a hollow anchor rod assembly, an optical fiber assembly, a fixing buckle and a distributed optical fiber demodulator, the hollow anchor rod assembly comprises a first hollow rod and a second hollow rod, an optical fiber small groove is formed in the inner wall of the bottom of the first hollow rod, and an optical fiber small groove is formed in the inner wall of the bottom of the second hollow rod. A middle groove and a large groove are formed in the inner wall of the bottom of the second hollow rod, the small optical fiber groove, the middle groove and the large groove are communicated, and the optical fiber assembly comprises an armored protective sleeve, a middle protective sleeve and a sensing optical fiber. According to the utility model, the optical fiber assemblies are embedded into the optical fiber small groove, the optical fiber middle groove and the optical fiber large groove, compared with the situation that the optical fiber assemblies are installed at other positions of the hollow anchor rod assembly, anchor rod strain data measured by sensing optical fibers are more accurate, and high-precision monitoring is achieved; the inner surface of the buckle is roughly wiped to increase the friction force, and then the fixing buckle and the optical fiber assembly are fastened on the inner wall of the hollow anchor rod through the fixing screw, so that the optical fiber assembly can be prevented from being separated from the groove or shifted due to the tensile force.

Description

Technical Field

[0001] The utility model relates to the technical field of geotechnical engineering monitoring, in particular to an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod. Background Art

[0002] The full-length grouting prestressed hollow anchor is an anchoring device that uses a slender hollow rod as a load-bearing component, with a pad, nut and other load-bearing accessories on the head. It is drilled in the rock mass and installed and anchored at the end. Prestress is applied, and then grouting is performed through the hollow hole to control the deformation of the rock mass. After the prestressed anchor is installed, high prestress acts on the rock mass through the grouting body, improving the stress state of the surrounding rock and thus increasing its bearing capacity. In order to understand the working state of the prestressed anchor, it is necessary to monitor the axial force of the anchor. Using OFDR distributed optical fiber for axial force monitoring can achieve high-density measurement point arrangement to obtain high-precision axial force and stress distribution.

[0003] For example, a full-stress optical fiber monitoring device for a threaded steel anchor rod with announcement number CN 108692771A and announcement date 2018.10.23 includes a threaded steel anchor rod and a distributed optical fiber sensor arranged along its entire length, and is characterized in that: fasteners are fixedly arranged at intervals on the threaded steel anchor rod along its length direction, and the distributed optical fiber sensor is connected to the fasteners to form a threaded steel anchor rod-distributed optical fiber sensor assembly; the distributed optical fiber sensor includes a distributed optical fiber strain sensor and a distributed optical fiber temperature sensor arranged at circumferential intervals along the cross-section of the threaded steel anchor rod.

[0004] As mentioned above and in the prior art, optical fibers are relatively fragile and are often laid out unilaterally in strip-shaped and tubular components. The laying methods in strip-shaped and tubular structures with different functions and structures are different. When laying optical fiber sensors in prestressed hollow anchor rods, the measurement data is not accurate enough, and the optical fiber is not well and reliably protected. In addition, the laying of optical fiber sensors will affect the grouting function of the hollow anchor rod. Therefore, it is urgent to design an optical fiber monitoring device for full-length grouting prestressed hollow anchor rods to solve the above problems. Utility Model Content

[0005] The utility model aims to provide an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod to solve the above-mentioned shortcomings in the prior art.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A fiber optic monitoring device for a full-length grouting prestressed hollow anchor rod, comprising a hollow anchor rod assembly, an optical fiber assembly, a fixing buckle and a distributed optical fiber demodulator, wherein the hollow anchor rod assembly comprises a hollow rod one and a hollow rod two, and a small optical fiber groove is provided on the inner wall of the bottom of the hollow rod one, a middle groove and a large groove are respectively provided on the inner wall of the bottom of the hollow rod two, and the small optical fiber groove, the middle groove and the large groove are connected, and the optical fiber assembly comprises an armored sheath tube, an intermediate sheath tube and a sensing optical fiber, the intermediate sheath tube is sleeved on the outside of the sensing optical fiber, the armored sheath tube is sleeved on the outside of the intermediate sheath tube, the sensing optical fiber is arranged inside the small optical fiber groove, the intermediate sheath tube is the same length as the middle groove, and the intermediate sheath tube is located inside the middle groove.

[0008] Furthermore, the gap between the middle groove and the middle sheath pipe, and the gap between the large groove and the armored sheath pipe are filled with epoxy resin adhesive, and an anchor stop plug is provided at the connection between the hollow rod 1 and the hollow rod 2.

[0009] Furthermore, a screw hole is provided on the inner wall of the hollow rod close to the large groove, a fixing screw is passed through the internal thread of the fixing buckle, and the fixing screw thread is inserted into the interior of the screw hole.

[0010] Furthermore, an anchor plate is provided on the outer sleeve of the hollow rod 1, and a nut is threadedly sleeved on the outer wall of the hollow rod 1.

[0011] Furthermore, a through hole is opened inside the anchor plate, and a grouting pipe is arranged on the outer wall of the bottom of the second hollow rod, and the grouting pipe runs through the inside of the through hole.

[0012] Furthermore, a grouting stopper is provided on the outer wall of one side of the anchor plate, and the grouting stopper is sleeved on the outside of the grouting pipe.

[0013] Furthermore, one end of the sensing optical fiber is connected to a distributed optical fiber demodulator, and the hollow anchor assembly is inserted into the interior of the rock mass, and the gap between the rock mass and the hollow anchor assembly is filled with grouting.

[0014] In the above technical scheme, the utility model provides an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod, (1) by setting the optical fiber small groove, middle groove, large groove, hollow rod one, hollow rod two, armored sheath tube, intermediate sheath tube and sensing optical fiber, the optical fiber assembly is embedded into the optical fiber small groove, middle groove and large groove. Compared with the anchor rod assembly installed at other positions, the anchor rod strain data measured by the sensing optical fiber is more accurate, thereby achieving high-precision monitoring; (2) by setting the screw hole, fixing buckle and fixing screw, the inner surface of the buckle is roughly rubbed to increase the friction force, and then the fixing buckle and the optical fiber assembly are fastened to the inner wall of the hollow anchor rod by using the fixing screw, so as to avoid the optical fiber assembly being tightly attached to the inner wall of the hollow anchor rod. The optical fiber will not fall out of the groove or be displaced by tension; (3) the armored sheath tube, the middle sheath tube, the sensing optical fiber and the middle groove are provided, the armored sheath tube and the middle sheath tube can protect the sensing optical fiber, and the optical fiber is embedded in the small groove, the middle groove and the large groove, which can provide good and reliable protection for the sensing optical fiber. At the same time, the middle groove is the same length as the middle sheath tube, and the middle groove can limit the middle sheath tube, which is convenient for assembly; (4) the grouting pipe and the grouting stopper are provided, and grouting can be performed through the grouting pipe, so that the hollow anchor rod is combined with the rock mass to form a monitoring structure of the anchor rod reinforcing the rock mass. Grouting is not performed from the inside of the hollow anchor rod, and the sensing optical fiber will not affect the grouting function. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present utility model. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0016] Figure 1 A three-dimensional cross-sectional structural schematic diagram is provided for an embodiment of an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod according to the utility model.

[0017] Figure 2 The utility model provides a three-dimensional cross-sectional structural schematic diagram of an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod.

[0018] Figure 3 A schematic diagram of the anchor pad structure provided for an embodiment of an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod according to the utility model.

[0019] Figure 4 The utility model provides a schematic diagram of the structure of an optical fiber assembly of an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod.

[0020] Figure 5A schematic diagram of the connection structure of a distributed optical fiber demodulator and a sensing optical fiber provided in an embodiment of an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod according to the utility model.

[0021] Description of reference numerals:

[0022] 1. Hollow anchor rod assembly; 2. Anchor rod stop plug; 3. Anchor pad; 4. Nut; 5. Optical fiber assembly; 6. Grouting pipe; 7. Grouting stop plug; 8. Optical fiber small groove; 9. Middle groove; 10. Large groove; 11. Hollow rod one; 12. Screw hole; 13. Fixing buckle; 14. Fixing screw; 15. Through hole; 16. Distributed optical fiber demodulator; 17. Hollow rod two; 18. Rock mass; 19. Armored sheath tube; 20. Intermediate sheath tube; 21. Sensing optical fiber. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0024] like Figure 1-5 As shown, an optical fiber monitoring device for a full-length grouting prestressed hollow anchor provided by an embodiment of the utility model comprises a hollow anchor assembly 1, an optical fiber assembly 5, a fixing buckle 13 and a distributed optical fiber demodulator 16, wherein the hollow anchor assembly 1 comprises a hollow rod 11 and a hollow rod 17, and a small optical fiber groove 8 is provided on the inner wall at the bottom of the hollow rod 11, a middle groove 9 and a large groove 10 are respectively provided on the inner wall at the bottom of the hollow rod 17, and the small optical fiber groove 8, the middle groove 9 and the large groove 10 are connected, and the optical fiber assembly 5 comprises an armored sheath tube 19, an intermediate sheath tube 20 and a sensing optical fiber 21, the intermediate sheath tube 20 is sleeved on the outside of the sensing optical fiber 21, the armored sheath tube 19 is sleeved on the outside of the intermediate sheath tube 20, the sensing optical fiber 21 is arranged inside the small optical fiber groove 8, the intermediate sheath tube 20 is the same length as the middle groove 9, and the intermediate sheath tube 20 is located inside the middle groove 9.

[0025] The utility model provides an optical fiber monitoring device for a full-length grouting prestressed hollow anchor rod, comprising a hollow anchor rod assembly 1, an optical fiber assembly 5, a fixing buckle 13 and a distributed optical fiber demodulator 16, wherein the hollow anchor rod assembly 1 comprises a hollow rod 11 and a hollow rod 2 17, and an optical fiber small groove 8 is provided on the inner wall at the bottom of the hollow rod 11, and a middle groove 9 and a large groove 10 are provided on the inner wall at the bottom of the hollow rod 2 17, respectively, and the optical fiber small groove 8, the middle groove 9 and the large groove 10 are connected, and the optical fiber assembly 5 comprises an armored sheath tube 19, an intermediate sheath tube 20 and a sensor light Fiber 21, the middle sheath tube 20 is sleeved on the outside of the sensing optical fiber 21, the armored sheath tube 19 is sleeved on the outside of the middle sheath tube 20, the sensing optical fiber 21 is arranged inside the small optical fiber groove 8, the middle sheath tube 20 is the same length as the middle groove 9, and the middle sheath tube 20 is located inside the middle groove 9, the optical fiber assembly 5 is buried in the small optical fiber groove 8, the middle groove 9 and the large groove 10, compared with other positions, the anchor strain data measured by grooving on the inner wall of the hollow anchor assembly 1 is more accurate, and it has a good and reliable protection function for the optical fiber assembly 5.

[0026] By embedding the optical fiber assembly 5 into the small optical fiber groove 8, the middle groove 9 and the large optical fiber groove 10, the anchor strain data measured by the sensing optical fiber 21 is more accurate compared with other positions installed in the hollow anchor assembly 1, thereby achieving high-precision monitoring.

[0027] In one embodiment provided by the present utility model, Figure 1 and Figure 2 As shown, the gap between the middle groove 9 and the middle jacket tube 20, and the gap between the large groove 10 and the armored jacket tube 19 are filled with epoxy resin adhesive, and an anchor stop plug 2 is provided at the connection between the hollow rod 11 and the hollow rod 2 17, which can fix the middle jacket tube 20 inside the middle groove 9 and the armored jacket tube 19 inside the large groove 10.

[0028] In another embodiment provided by the present utility model, Figure 1 and Figure 2 As shown, a screw hole 12 is provided on the inner wall of the hollow rod 11 near the large groove 10, and a fixing screw 14 is passed through the internal thread of the fixing buckle 13, and the fixing screw 14 is threadedly inserted into the inside of the screw hole 12, so as to fix the armored sheath tube 19.

[0029] In another embodiment provided by the present utility model, Figure 1 , 2 and Figure 3 As shown, the outer sleeve of the hollow rod 11 is provided with an anchor plate 3, and a nut 4 is threadedly sleeved on the outer wall of the hollow rod 11, and the nut 4 cooperates with the rock mass 18 to squeeze and fix the anchor plate 3.

[0030] In one embodiment provided by the present utility model, Figure 1 , 2 and Figure 3 As shown, a through hole 15 is opened inside the anchor plate 3 , and a grouting pipe 6 is arranged on the outer wall of the bottom of the hollow rod 17 , and the grouting pipe 6 runs through the inside of the through hole 15 .

[0031] In another embodiment provided by the present utility model, Figure 1 and Figure 2 As shown, a grouting stopper 7 is provided on the outer wall of one side of the anchor plate 3 , and the grouting stopper 7 is sleeved on the outside of the grouting pipe 6 , and the grouting pipe 6 is used for grouting the gap between the rock mass 18 and the hollow anchor assembly 1 .

[0032] In another embodiment provided by the present utility model, Figure 5 As shown, one end of the sensing optical fiber 21 is connected to the distributed optical fiber demodulator 16, and the hollow anchor assembly 1 is inserted into the rock mass 18, and the gap between the rock mass 18 and the hollow anchor assembly 1 is filled with grouting to fix the hollow anchor assembly 1 inside the rock mass 18.

[0033] Working principle: a small optical fiber groove 8 is opened on the inner wall of the hollow rod 2 17 of the hollow anchor rod assembly 1, and a middle groove 9 and a large groove 10 are opened on the inner wall of the hollow rod 1 11, and the sensing optical fiber 21 is buried in the small optical fiber groove 8. The two sections are stretched straight, and epoxy resin adhesive is used to bond the small optical fiber groove 8 along the entire length, and the filling is dense. The adhesive is loosened after solidification. Compared with other positions, the anchor strain data measured by the groove on the inner wall of the anchor hollow anchor rod assembly 1 is more accurate; the size of the middle groove 9 should be slightly larger than the size of the middle sheath tube 20 and should not be too large, the sensing optical fiber 21 is inserted into the middle sheath tube 20, and then placed in the middle groove 9, the middle sheath tube 20 should be placed straight against the bottom of the middle groove 9, and cannot be bent, the gap between the middle groove 9 and the middle sheath tube 20 is filled with epoxy resin adhesive for bonding, and the gap is filled densely; the size of the large groove 10 should be slightly larger than the size of the armored sheath tube 19 and should not be too large, The sensing optical fiber 21 and the intermediate sheath tube 20 are inserted into the armored sheath tube 19 for protection, and then placed into the large groove 10. The gap between the large groove 10 and the armored sheath tube 19 is filled with epoxy resin adhesive for bonding, and the gap is filled densely; then the fixing buckle 13 is clamped on the top of the armored sheath tube 19, and the inner surface of the fixing buckle 13 is roughly rubbed to increase friction. Then the fixing screw 14 is turned to fasten the fixing buckle 13 and the armored optical fiber to the inner wall of the anchor rod to prevent the optical fiber assembly 5 from being pulled out of the groove or displaced. The sensing optical fiber 21 is directly led out from the hollow anchor rod assembly 1, but the hollow anchor rod assembly 1 can no longer be used as a grouting hole. The grouting pipe 6 is passed from the through hole 15 through the anchor pad 3 into the rock mass 18 borehole, and finally the optical fiber terminal is connected to the distributed optical fiber demodulator 16, and the optical fiber signal is read and converted into an electrical signal to monitor the strain value of the anchor rod.

[0034] The above only describes some exemplary embodiments of the present invention by way of illustration. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An optical fiber monitoring device for a full-length grouting prestressed hollow anchor, comprising a hollow anchor assembly (1), an optical fiber assembly (5), a fixing buckle (13) and a distributed optical fiber demodulator (16), characterized in that: The hollow anchor rod assembly (1) comprises a hollow rod 1 (11) and a hollow rod 2 (17), and a small optical fiber groove (8) is provided on the inner wall at the bottom of the hollow rod 1 (11), and a middle groove (9) and a large groove (10) are respectively provided on the inner wall at the bottom of the hollow rod 2 (17), and the small optical fiber groove (8), the middle groove (9) and the large groove (10) are connected. The optical fiber assembly (5) comprises an armored sheath tube (19), an intermediate sheath tube (20) and a sensing optical fiber (21), wherein the intermediate sheath tube (20) is sleeved on the outside of the sensing optical fiber (21), and the armored sheath tube (19) is sleeved on the outside of the intermediate sheath tube (20), and the sensing optical fiber (21) is arranged inside the small optical fiber groove (8), and the intermediate sheath tube (20) has the same length as the middle groove (9), and the intermediate sheath tube (20) is located inside the middle groove (9).

2. The optical fiber monitoring device for a full-length grouting prestressed hollow anchor according to claim 1, characterized in that: The gap between the middle groove (9) and the middle sheath tube (20), and the gap between the large groove (10) and the armored sheath tube (19) are filled with epoxy resin adhesive, and an anchor stop plug (2) is provided at the connection between the hollow rod 1 (11) and the hollow rod 2 (17).

3. The optical fiber monitoring device for a full-length grouting prestressed hollow anchor according to claim 2, characterized in that: A screw hole (12) is provided on the inner wall of the hollow rod (11) near the large groove (10), and a fixing screw (14) is passed through the internal thread of the fixing buckle (13), and the fixing screw (14) is threadedly inserted into the inside of the screw hole (12).

4. The optical fiber monitoring device for a full-length grouting prestressed hollow anchor according to claim 3, characterized in that: The outer sleeve of the hollow rod 1 (11) is provided with an anchor plate (3), and a nut (4) is threadedly sleeved on the outer wall of the hollow rod 1 (11).

5. The optical fiber monitoring device for a full-length grouting prestressed hollow anchor according to claim 4, characterized in that: A through hole (15) is provided inside the anchor pad (3), and a grouting pipe (6) is provided on the outer wall of the bottom of the second hollow rod (17), and the grouting pipe (6) passes through the inside of the through hole (15).

6. The optical fiber monitoring device for a full-length grouting prestressed hollow anchor according to claim 5, characterized in that: A grouting stop plug (7) is provided on the outer wall of one side of the anchor pad (3), and the grouting stop plug (7) is sleeved on the outside of the grouting pipe (6).

7. The optical fiber monitoring device for a full-length grouting prestressed hollow anchor according to claim 6, characterized in that: One end of the sensing optical fiber (21) is connected to a distributed optical fiber demodulator (16), and the hollow anchor rod assembly (1) is inserted into the interior of the rock mass (18), and the gap between the rock mass (18) and the hollow anchor rod assembly (1) is filled with grouting.

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