Weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring

Abstract

A weak grating inclination and displacement integrated sensor for monitoring dangerous rock masses, the sensor includes a weak grating inclination sensor, a weak grating displacement sensor, and a fifth FBG fiber grating; the weak grating inclination sensor includes a first optical fiber, and the weak grating displacement sensor includes a second optical fiber; the weak grating inclination sensor is arranged on the top cover of the weak grating displacement sensor, and a through hole is provided on the top cover, one end of the second optical fiber passes through the through hole and is fused with one end of the first optical fiber, and the other end of the first optical fiber is fused with one end of the fifth FBG fiber grating. The other end of the fifth FBG fiber grating passes through the top cover of the weak grating displacement sensor through the through hole; the other end of the second optical fiber passes through the side of the weak grating displacement sensor. The sensor of the present invention is easy to install; and can simultaneously measure the inclination components of the dangerous rock mass in two directions and the displacement of the crack, with strong anti-interference ability and high monitoring accuracy.

Description

Technical Field

[0001] The invention discloses a weak grating sensor, and in particular relates to a weak grating inclination and displacement integrated sensor for monitoring dangerous rock masses. Background Art

[0002] With the rapid development of my country's economy, the country has invested more and more in infrastructure construction. There are more and more water conservancy and hydropower projects, tunnel projects, etc. being built in southwest my country. Disasters caused by the collapse of dangerous rock masses on steep slopes are becoming more and more serious. Dangerous rocks are rock blocks or groups of blocks with poor stability that are cut by multiple rock structure surfaces on steep slopes or cliffs. The formation, instability and movement of dangerous rocks are the main manifestations of slope dynamic geomorphic processes. Dangerous rock masses are potential collapse bodies, which can easily cause the collapse of a single rock mass or even the mass collapse of multiple dangerous rock masses. Once a disaster occurs, it will affect road traffic and waterway navigation at the least, and cause serious loss of life and property at the worst, seriously affecting the development of the economy and society, and is seriously harmful.

[0003] At present, the monitoring of crack displacement and inclination of dangerous rock masses mainly adopts two kinds of sensors: electronic displacement and inclination. The deployment is relatively cumbersome. Electronic sensors are easily disturbed by external factors such as lightning, high temperature, etc., which affects the accuracy of monitoring data. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring, which is easy to install and can simultaneously measure the inclination components in two directions of the dangerous rock mass and the displacement of the cracks, has strong anti-interference ability and high monitoring accuracy.

[0005] The technical solution adopted by the present invention is:

[0006] Weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring, the sensor includes:

[0007] Weak grating inclination sensor, weak grating displacement sensor, fifth FBG fiber Bragg grating;

[0008] A weak grating tilt sensor and a fifth FBG fiber grating are arranged in the housing;

[0009] A weak grating displacement sensor is provided below the housing;

[0010] The weak grating tilt sensor includes a first optical fiber, and the weak grating displacement sensor includes a second optical fiber;

[0011] The weak grating inclination sensor is arranged on the top cover of the weak grating displacement sensor, and a through hole is provided on the top cover, one end of the second optical fiber passes through the through hole and is fused with one end of the first optical fiber, and the other end of the first optical fiber is fused with one end of the fifth FBG optical fiber grating. The other end of the fifth FBG optical fiber grating passes through the top cover of the weak grating displacement sensor through the through hole and then passes out from the side, and the other end of the second optical fiber passes out from the side of the weak grating displacement sensor.

[0012] The weak grating inclination sensor comprises a first equal strength beam, a second equal strength beam, a third equal strength beam, a fourth equal strength beam, a first limit block, a second limit block, a third limit block, a fourth limit block, a first pendulum, a second pendulum, a first lining plate, and a second lining plate;

[0013] A first FBG fiber grating, a second FBG fiber grating, a third FBG fiber grating, and a fourth FBG fiber grating are engraved on the first optical fiber;

[0014] The first equal strength beam is connected to a first FBG fiber grating;

[0015] The second equal strength beam is connected to the second FBG fiber grating;

[0016] The third equal strength beam is connected to the third FBG fiber grating;

[0017] The fourth equal strength beam is connected to the fourth FBG fiber grating;

[0018] The first lining plate is fixed with a first limit block, a second limit block, and a first pendulum, and the first limit block and the second limit block are fixed to the first lining plate; the first pendulum is fixed to the first lining plate through a rotating shaft swinging along the x direction; the first limit block and the second limit block are used to prevent the first pendulum from moving;

[0019] The second lining plate is fixed with a third limit block, a fourth limit block and a second pendulum, the third limit block and the fourth limit block are fixed to the second lining plate; the second pendulum is fixed to the second lining plate via a rotating shaft swinging along the y direction; the third limit block and the fourth limit block are used to prevent the second pendulum from moving;

[0020] The first lining plate and the second lining plate are fixed together vertically.

[0021] The weak grating displacement sensor comprises a fifth equal strength beam, a spring, a first thin steel wire rope, a large pulley, a small pulley, a bottom plate, a support block, and a second thin steel wire rope;

[0022] The second optical fiber is engraved with a sixth FBG optical fiber grating, and the sixth FBG optical fiber grating is connected to the fifth equal strength beam;

[0023] The support block is connected to the bottom plate, and the fifth equal strength beam is fixed on the support block;

[0024] The large pulley and the small pulley are respectively fixed to the bottom plate through rotating shafts;

[0025] The spring is connected to the fifth equal strength beam through a second thin steel wire rope;

[0026] The first thin steel wire rope is wound around the main disk of the large pulley. When the first thin steel wire rope is pulled, the main disk rotates and drives the sub-disk of the large pulley to rotate, so that the second thin steel wire rope is pulled and slowly wound around the sub-disk.

[0027] A method for monitoring the inclination angle and crack displacement of dangerous rock mass: under the swing of the internal pendulum, the weak grating inclination sensor causes tensile strain on one side of the equal-strength beam, resulting in wavelength drift of the fiber grating on the equal-strength beam; driven by a thin steel wire rope, the weak grating displacement sensor causes tensile strain on the fifth equal-strength beam, resulting in wavelength drift of the sixth FBG fiber grating. By demodulating the wavelength value, the inclination angle of the rock mass and the displacement of the crack are obtained.

[0028] The present invention provides a weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring, and the technical effects are as follows:

[0029] The sensor integrates two parameter sensors into one, which simplifies the installation of sensors in dangerous rock mass monitoring. According to the number of dangerous rocks on site, multiple inclination and displacement integrated sensors can be connected in series through a blank optical cable, giving full play to the advantages of weak grating large-capacity sensing. At the same time, weak grating sensors replace electronic sensors, enhancing the system's anti-interference ability. In the measurement process, it is real-time and responsive, and can simultaneously monitor the inclination of dangerous rock masses and the displacement of cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the sensor structure of the present invention.

[0031] Figure 2 It is a schematic diagram of the structure of the weak grating tilt sensor of the sensor of the present invention.

[0032] Figure 3 It is a schematic structural diagram of the weak grating rope displacement sensor of the sensor of the present invention.

[0033] Figure 4 This is a schematic diagram of the field application of the sensor of the present invention. DETAILED DESCRIPTION

[0034] Weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring, the sensor includes:

[0035] Housing 1, weak grating tilt sensor 2, weak grating displacement sensor 3, fifth FBG fiber Bragg grating 4;

[0036] The weak grating displacement sensor 3 is arranged at the bottom of the housing 1, and the fifth FBG fiber grating 4 is pasted on the inner wall of the housing 1;

[0037] The weak grating tilt sensor 2 is arranged on the top cover of the weak grating displacement sensor 3, and a through hole is left on the top cover, one end of the second optical fiber 39 passes through the through hole and is fused with one end of the first optical fiber 215, and the other end of the first optical fiber 215 of the weak grating tilt sensor 2 is fused with one end of the fifth FBG optical fiber grating 4;

[0038] The other end of the fifth FBG fiber grating 4 passes through the top cover of the weak grating displacement sensor 3 through the via hole and then passes out from the side. The other end of the second optical fiber 39 passes out from the side of the weak grating displacement sensor 3 to form the input and output interfaces of the entire sensor.

[0039] The weak grating tilt sensor 2 is composed of two orthogonal single-component weak grating tilt sensors.

[0040] The weak grating inclination sensor 2 includes a first equal-strength beam 25, a second equal-strength beam 28, a third equal-strength beam 211, a fourth equal-strength beam 212, a first limit block 24, a second limit block 29, a third limit block 210, a fourth limit block 213, a first pendulum 21, a second pendulum 214, a first optical fiber 215, a first lining plate 216, and a second lining plate 217.

[0041] The first optical fiber 215 is inscribed with a first FBG optical fiber grating 22, a second FBG optical fiber grating 23, a third FBG optical fiber grating 26, and a fourth FBG optical fiber grating 27;

[0042] The first FBG fiber grating 22 is pasted on the first equal strength beam 25;

[0043] The second FBG fiber grating 23 is pasted on the second equal strength beam 28;

[0044] The third FBG fiber grating 26 is pasted on the third equal strength beam 211;

[0045] The fourth FBG fiber grating 27 is attached to the fourth equal-strength beam 212 .

[0046] The first limit block 24, the second limit block 29 and the first pendulum 21 are fixed on the first lining plate 216. The first limit block 24 and the second limit block 29 are fixed to the first lining plate 216 by welding. The first pendulum 21 is fixed to the first lining plate 216 by a rotating shaft, and the rotating shaft can only swing along the x direction. When the first pendulum 21 moves to the first limit block 24 or the second limit block 29, the movement will be prevented by the limit block to achieve the purpose of protecting the weak grating.

[0047] The third limit block 210, the fourth limit block 213 and the second pendulum 214 are fixed on the second lining plate 217. The third limit block 210 and the fourth limit block 213 are fixed to the second lining plate 217 by welding. The second pendulum 214 is fixed to the second lining plate 217 by a rotating shaft, and the rotating shaft can only swing along the y direction. When the second pendulum 214 moves to the third limit block 210 or the fourth limit block 213, the movement will be prevented by the limit block to achieve the purpose of protecting the weak grating.

[0048] The first lining plate 216 and the second lining plate 217 are fixed together by welding. During the welding process, the first lining plate 216 and the second lining plate 217 must be vertical.

[0049] The first equal strength beam 25, the second equal strength beam 28, the third equal strength beam 211, and the fourth equal strength beam 212 are all made of material HT250.

[0050] One end of the first equal-strength beam 25 is attached to the first limit block 24 (it cannot be attached to the first FBG fiber grating 22 ), and the other end is attached to the connecting rod of the first pendulum 21 .

[0051] One end of the second equal-strength beam 28 is attached to the second limit block 29 (it cannot be attached to the second FBG fiber grating 23 ), and the other end is attached to the connecting rod of the first pendulum 21 .

[0052] One end of the third equal-strength beam 211 is attached to the third limit block 210 (it cannot be attached to the third FBG fiber grating 26 ), and the other end is attached to the connecting rod of the second pendulum 214 .

[0053] One end of the fourth equal-strength beam 212 is attached to the fourth limit block 213 (it cannot be attached to the fourth FBG fiber grating 27 ), and the other end is attached to the connecting rod of the second pendulum 214 .

[0054] The weak grating displacement sensor 3 comprises a sixth FBG fiber Bragg grating 31, a fifth equal strength beam 32, a spring 33, a first thin steel wire rope 34, a large pulley 35, a small pulley 36, a bottom plate 37, a support block 38, an optical fiber 39, and a second thin steel wire rope 310; the second optical fiber 39 is engraved with the sixth FBG fiber Bragg grating 31;

[0055] The sixth FBG optical fiber grating 31 is pasted on the fifth equal-strength beam 32; the support block 38 is welded on the base plate 37, and the fifth equal-strength beam 32 is fixed on the support block 38; the large pulley 35 and the small pulley 36 are respectively fixed on the base plate 37 using rotating shafts; the spring 33 is connected to the equal-strength beam 32 through the second thin steel wire rope 310; the second thin steel wire rope 310 passes around the small pulley 36 and is wound around the sub-disk 311.

[0056] The first thin steel wire rope 34 is tightly wound on the main plate of the large pulley 35. When the first thin steel wire rope 34 is pulled, the main plate rotates and drives the sub-plate 311 of the large pulley 35 to rotate, so that the second thin steel wire rope 310 is pulled and slowly wound on the sub-plate 311. The diameter of the main plate D 主 The diameter of the sub-disk D 子 The ratio is optional, the larger the ratio, the larger the sensor range.

[0057] During the design process, the thickness of the large pulley 35 and the small pulley 36 are the same, and the center thickness of the support block 38 and the small pulley 36 are consistent, so that the force level can be guaranteed as much as possible and the measurement accuracy can be enhanced.

[0058] The principle of the dangerous rock mass inclination and crack displacement monitoring method is:

[0059] The weak grating inclination sensor 2 generates tensile strain on one side of the equal-strength beam under the swing of the internal pendulum, causing the wavelength drift of the fiber grating on the equal-strength beam; the weak grating displacement sensor 3, driven by the wire rope, generates tensile strain on the fifth equal-strength beam 32, causing the wavelength drift of the sixth FBG fiber grating 31. By demodulating the wavelength value, the inclination of the rock mass and the displacement of the crack are obtained.

[0060] The inclination monitoring method of dangerous rock mass, when the weak grating inclination and displacement integrated sensor is placed in a vertical state, it is set to a non-inclination state, and the inclination angle θ at this time is 0; when the rock mass tilts to the right, the first pendulum 21 deviates to the right under the action of gravity, and the weak grating inclination sensor 2 generates an inclination angle θ, and the first equal-strength beam 25 on the left side will bend and deform due to the stretching of the first pendulum 21. At this time, the first FBG fiber grating 22 pasted on the upper side of the first equal-strength beam 25 will have a wavelength shift due to the positive strain. Assume that the wavelength drift of the first FBG fiber grating 22 is △λ1, and the wavelength drift of the fifth FBG fiber grating 4 affected by temperature is △λ2, and the difference information △λ between the wavelength drift of the first FBG fiber grating 22 and the fifth FBG fiber grating 4 is obtained. 12 =△λ1-△λ2, converted by calibration formula (2), the current inclination angle θ is obtained;

[0061] The calibration formula is obtained through indoor calibration. After the inclination sensor is manufactured, the inclination sensor is placed on the inclination calibration table, and the angle of the inclination table is adjusted in the x direction (-10°—+10°) to obtain the formula

[0062] K θ =Δλ 12 / Δθ (1)

[0063] Then θ=θ0+Δλ 12 / K θ (2)

[0064] Where: θ0 is the initial state inclination, K θ is the linear coefficient of wavelength and inclination angle.

[0065] Similarly, when the rock mass tilts in the opposite direction, the wavelength of the second FBG fiber grating 23 will also drift due to the positive strain, thereby detecting the current tilt angle θ.

[0066] The method for monitoring the displacement of cracks in dangerous rock bodies is as follows: when the first steel wire rope 34 is pulled out, the large pulley 35 and the small pulley 36 are driven to rotate, the spring 33 is stretched, and the fifth equal strength beam 32 is pulled to deform, so that the wavelength of the sixth FBG fiber grating 31 pasted on the fifth equal strength beam 32 changes. According to the fiber Bragg grating sensing principle, the following expression can be obtained:

[0067]

[0068] Where: B is the central wavelength of the measured grating, △λ B Indicates the drift of the grating center wavelength, K T and K ε are the temperature sensitivity coefficient and gauge coefficient of the grating, K ε =1-P, P is the elastic-optical coefficient of the fiber Bragg grating, △T and ε are the temperature change and axial strain change of the environment in which the grating is located, respectively.

[0069] The sixth FBG fiber grating 31 and the fifth FBG fiber grating 4 have the same temperature sensitivity coefficient, and the two fiber gratings are at the same ambient temperature, and the wavelength drift of the fifth FBG fiber grating 4 is only affected by temperature by Δλ2; the measured wavelength drift of the sixth FBG fiber grating 31 is Δλ3, and the difference information Δλ between the wavelength drift of the sixth FBG fiber grating 31 and the fifth FBG fiber grating 4 is calculated. 32 =Δλ3-Δλ2, combined with formula (3), we can get Δλ 32 Only related to (1-P)ε.

[0070] Therefore, the displacement change of the first steel wire rope 34 can be calculated by calibration formula (5), that is, the displacement change of the crack.

[0071] The calibration formula is obtained through indoor calibration. After the displacement sensor is manufactured, it is placed on the displacement calibration table, the sensor and the wire rope are fixed, and the wire rope is stretched from 0mm to 500mm to obtain the formula:

[0072] K L =Δλ 32 / ΔL (4)

[0073] Then L=L0+Δλ 23 / K L (5)

[0074] Where: L0 is the initial state displacement, K L is the linear coefficient of wavelength and displacement.

[0075] Shell 1 is a heat-insulating shell, which is mainly used to reduce the fluctuation of the internal temperature of the sensor. In the monitoring of dangerous rock masses, the outdoor environment is relatively harsh. When the sun shines directly on the rock, the surface temperature is high, resulting in a large temperature difference between the monitoring point in the morning, noon and evening, which is easy to cause measurement errors. The use of a heat-insulating shell can greatly improve the accuracy of the sensor. The shell and top cover of the weak grating displacement sensor 3 are made of the same material as the shell 1.

[0076] The weak grating inclination sensor 2 is composed of two single-component weak grating inclination sensors formed by an orthogonal combination, so the inclination degree of the rock in all directions can be measured.

[0077] The first FBG fiber grating 22, the second FBG fiber grating 23, the third FBG fiber grating 26 and the fourth FBG fiber grating 27 are all fixed to the upper side of the equal strength beam by 353ND adhesive. The FBG fiber gratings are all weak gratings with a reflectivity of less than 0.1%.

[0078] In the weak grating displacement sensor 3, the measuring range of the displacement sensor is designed according to the elastic coefficient of the spring 33, and the measuring range is generally designed to be above 400 mm.

[0079] like Figure 4 As shown, according to the number of dangerous rock bodies B on site, multiple weak grating inclination and displacement integrated sensors A can be connected in series through a connecting optical cable C, and the connecting optical cable C is connected to the weak grating demodulator D.

[0080] The weak grating interrogator D uses the RS-HFBGA-04 portable analyzer.

[0081] The weak grating inclination and displacement integrated sensor A is easy to install and practical. The inclination angle measurement range is -10° to +10°, the measurement accuracy is 0.01°, the maximum displacement measurement value is 500mm, and the displacement resolution is 0.2mm.

Claims

1. Weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring, characterized by The sensor includes: A weak grating inclination sensor (2), a weak grating displacement sensor (3), and a fifth FBG fiber grating (4); A weak grating tilt sensor (2) and a fifth FBG optical fiber grating (4) are arranged in the housing (1); A weak grating displacement sensor (3) is provided below the housing (1); The weak grating inclination sensor (2) comprises a first optical fiber (215), and the weak grating displacement sensor (3) comprises a second optical fiber (39); The weak grating inclination sensor (2) is arranged on the top cover of the weak grating displacement sensor (3), and a through hole is provided on the top cover, one end of the second optical fiber (39) passes through the through hole and is fused with one end of the first optical fiber (215), and the other end of the first optical fiber (215) is fused with one end of the fifth FBG optical fiber grating (4); The other end of the fifth FBG optical fiber grating (4) passes through the through hole, through the top cover of the weak grating displacement sensor (3), and then passes out from the side; the other end of the second optical fiber (39) passes out from the side of the weak grating displacement sensor (3); The weak grating inclination sensor (2) comprises a first equal strength beam (25), a second equal strength beam (28), a third equal strength beam (211), a fourth equal strength beam (212), a first limit block (24), a second limit block (29), a third limit block (210), a fourth limit block (213), a first pendulum (21), a second pendulum (214), a first lining plate (216), and a second lining plate (217); A first FBG fiber grating (22), a second FBG fiber grating (23), a third FBG fiber grating (26), and a fourth FBG fiber grating (27) are inscribed on the first optical fiber (215); The first equal strength beam (25) is connected to the first FBG fiber grating (22); The second equal strength beam (28) is connected to the second FBG fiber grating (23); The third equal strength beam (211) is connected to the third FBG optical fiber grating (26); The fourth equal-strength beam (212) is connected to a fourth FBG optical fiber grating (27); A first limit block (24), a second limit block (29) and a first pendulum (21) are fixed on the first lining plate (216); the first limit block (24) and the second limit block (29) are fixed on the first lining plate (216); the first pendulum (21) is fixed on the first lining plate (216) via a rotating shaft that swings along the x-direction; the first limit block (24) and the second limit block (29) are used to prevent the first pendulum (21) from moving; A third limit block (210), a fourth limit block (213) and a second pendulum (214) are fixed on the second lining plate (217); the third limit block (210) and the fourth limit block (213) are fixed on the second lining plate (217); the second pendulum (214) is fixed on the second lining plate (217) via a rotating shaft that swings along the y direction; the third limit block (210) and the fourth limit block (213) are used to prevent the second pendulum (214) from moving; The first lining plate (216) and the second lining plate (217) are fixed together vertically; One end of the first uniform strength beam (25) is attached to the first limit block (24), and the other end is attached to the connecting rod of the first pendulum (21); One end of the second equal strength beam (28) is attached to the second limit block (29), and the other end is attached to the connecting rod of the first pendulum (21); One end of the third equal-strength beam (211) is attached to the third limit block (210), and the other end is attached to the connecting rod of the second pendulum (214); One end of the fourth equal-strength beam (212) is adhered to the fourth limit block (213), and the other end is adhered to the connecting rod of the second pendulum (214).

2. The weak grating inclination and displacement integrated sensor for dangerous rock mass monitoring according to claim 1, characterized in that: The weak grating displacement sensor (3) comprises a fifth equal strength beam (32), a spring (33), a first thin steel wire rope (34), a large pulley (35), a small pulley (36), a bottom plate (37), a support block (38), and a second thin steel wire rope (310); The second optical fiber (39) is engraved with a sixth FBG optical fiber grating (31), and the sixth FBG optical fiber grating (31) is connected to the fifth equal strength beam (32); The support block (38) is connected to the bottom plate (37), and the fifth equal strength beam (32) is fixed on the support block (38); The large pulley (35) and the small pulley (36) are respectively fixed on the bottom plate (37) via rotating shafts; The spring (33) is connected to the fifth equal strength beam (32) via a second thin steel wire rope (310); The first thin steel wire rope (34) is wound around the main disc of the large pulley (35). When the first thin steel wire rope (34) is pulled, the main disc rotates and drives the sub-disc (311) of the large pulley (35) to rotate, so that the second thin steel wire rope (310) is pulled and slowly wound around the sub-disc (311).

3. A method for monitoring the inclination angle and crack displacement of a dangerous rock mass using the sensor according to claim 1 or 2, characterized in that: The weak grating inclination sensor (2) generates tensile strain on one side of the equal strength beam under the swing of the internal pendulum, causing the wavelength of the fiber grating on the equal strength beam to drift; the weak grating displacement sensor (3) generates tensile strain on the fifth equal strength beam (32) under the drive of the thin steel wire rope, causing the wavelength of the sixth FBG fiber grating (31) to drift, and the inclination of the rock mass and the displacement of the crack are obtained by demodulating the wavelength value.

4. A method for monitoring the inclination of a dangerous rock mass using the sensor according to claim 1 or 2, characterized in that: When the weak grating inclination and displacement integrated sensor is placed in a vertical state, it is set to a non-inclination state, and the inclination angle θ is 0 at this time; When the rock mass tilts to the right, the first pendulum (21) deflects to the right under the action of gravity. At this time, the weak grating tilt sensor (2) generates a tilt angle θ. The first equal strength beam (25) on the left side will bend and deform due to the stretching of the first pendulum (21). At this time, the first FBG fiber grating (22) attached to the upper side of the first equal strength beam (25) will shift its wavelength due to the positive strain. Assuming that the wavelength drift of the first FBG fiber grating (22) is △λ1, and the wavelength drift of the fifth FBG fiber grating (4) affected by temperature is △λ2, the difference information △λ between the wavelength drifts of the first FBG fiber grating (22) and the fifth FBG fiber grating (4) is obtained. 12 =△λ1-△λ2, converted by calibration formula (2), the current inclination angle θ is obtained; K θ =Dl 12 / Dth (1) If θ=θ0+Δλ 12 / K θ (2) Where: θ0 is the initial state inclination, K θ is the linear coefficient of wavelength and inclination angle.

5. A method for monitoring the inclination of a dangerous rock mass using the sensor as claimed in claim 2, characterized in that: When the first thin steel wire rope (34) is pulled out, the large pulley (35) and the small pulley (36) are driven to rotate, the spring (33) is stretched, and the fifth equal strength beam (32) is pulled to deform, so that the wavelength of the sixth FBG fiber grating (31) attached to the fifth equal strength beam (32) changes; according to the fiber Bragg grating sensing principle, the following expression can be obtained: Where: B is the central wavelength of the measured grating, △λ B Indicates the drift of the grating center wavelength, K T and K ε are the temperature sensitivity coefficient and gauge coefficient of the grating, K ε =1-P, P is the elastic-optic coefficient of the fiber Bragg grating, △T and ε are the temperature change and axial strain change of the environment where the grating is located respectively; The sixth FBG optical fiber Bragg grating (31) and the fifth FBG optical fiber Bragg grating (4) have the same temperature sensitivity coefficient, and the two optical fiber Bragg gratings are under the same ambient temperature, and the wavelength drift amount of the fifth FBG optical fiber Bragg grating (4) affected by temperature is Δλ2; the measured wavelength drift amount of the sixth FBG optical fiber Bragg grating (31) is Δλ3, and the difference information Δλ between the wavelength drift amounts of the sixth FBG optical fiber Bragg grating (31) and the fifth FBG optical fiber Bragg grating (4) is obtained. 32 =Δλ3-Δλ2, combined with formula (3), we can get Δλ 32 It is only related to (1-P)ε; Thus, the displacement change of the first thin steel wire rope (34) is calculated by calibration formula (5), which is the displacement change of the crack; K L =Dl 32 / ΔL (4) If L=L0+Δλ 23 / K L (5) Where: L0 is the initial state displacement, K L is the linear coefficient of wavelength and displacement.

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