TWI588322B - Pier scour depth sensor - Google Patents

Description

Pier scouring depth sensor

The invention relates to the field of detecting piers, in particular to a pier scouring depth sensor.

Bridge pier support bridges are used for traffic on both sides of the waters and are one of the infrastructures for transportation. The direction of water flow in the water will cause erosion of the pier, causing the loss of sand, stone and soil. Especially in areas with frequent natural disasters, a large amount of rainwater will not only cause earth-rock flow, but also cause collapse of mountains or slopes. It will also cause the rivers or streams to skyrocket and deepen the degree of erosion, so that the piles of the piers are exposed and the load on the bridge is relatively reduced. the amount. In severe cases, the pier is tilted or broken, causing the bridge to fall into the water, causing traffic disruption.

Therefore, monitoring the scouring depth of the pier, early detection, immediate reinforcement or maintenance, in addition to extending the service life of the bridge, can also establish complete monitoring data, serving as a reference for subsequent pier protection and river bed remediation.

There are quite a lot of monitoring techniques for the piercing depth of the pier, such as Ground Penetrating Radar, Numbered bricks, Sliding magnetic collar, outdoor surveillance lens identification water level method, self-moving Lens monitoring method, multi-lens monitoring method, transmitter type soil erosion monitoring system, fiber optic sensor and probe monitoring method.

A fiber optic sensor, referred to herein, typically utilizes a fiber Bragg grating as a supervised measurement tool or system. Because the medium is attached to the fiber, the grating pitch of the fiber Bragg grating is changed, causing the wavelength of the light to drift, and the depth of the medium can be analyzed. The disadvantage is that the fiber of this method needs to be buried in the riverbed, and the fiber is relatively fragile and easily damaged by external forces.

As for the shortcomings of the probe monitoring method, the water surface is too high from the sand surface, and the length of the rod to be measured is longer. If the water level soars, the probe-type monitoring device is vulnerable to external forces such as flooding or boulder.

In order to improve the drawbacks of the probe monitoring method, the invention patent No. I410551 discloses a telescopic probe monitoring system for the height of the bridge bottom bed, which is composed of a measuring module and a control module. The measuring module has a casing, a multi-layer pipe body, a pushing unit, a photographing unit and a sensing unit. The pushing unit has a plurality of scales, and is operated by the control module to extend the multi-layer pipe body toward the bottom bed. The sensing unit is disposed at the bottom of the multi-layer tube. When the sensing unit touches the bottom bed, a signal is sent to the control module, and the photographing unit controls the photographing unit to take an image transmitted to the remote monitoring unit. The control module knows the operating state of the image or measurement module, knows the elevation of the bottom bed of the bridge and stops the elongation of the multi-layer tube, and instantly monitors the elevation of the bed.

However, the operator of the multi-layered tube requires multiple accumulations of experience in order to determine the effective length of the multi-layered tube extension from the image. Moreover, the excellent waterproof performance leads to high prices of the photography unit, which increases the unnecessary manufacturing cost.

Therefore, how to improve the pier scouring depth sensor has become an urgent problem to be solved by the present invention.

In view of this, the present invention provides a bridge piercing depth sensor, the main purpose of which is to adopt a structure in which the depth bit energy can be converted into an axial bit energy, and the fiber sensing device is used to effectively solve the drawbacks of the prior art regarding the embedding of the fiber into the river bed. It has the measurement effect of the piercing depth.

Due to the above object, the pier scouring depth sensor of the present invention comprises: a depth measuring unit having a hammer body and a rope connecting the hammer body, the rope supporting the hammer body to contact the river bed by gravity; a conversion unit for converting the depth of the river bed into an axial displacement change; and a light sensing unit having an optical fiber and an optical fiber disposed on the optical fiber The Bragg grating allows light of a certain wavelength to be output to the fiber Bragg grating via the optical fiber, and the fiber Bragg grating receives the axial displacement variation of the conversion unit to generate the grating pitch extension for detecting the flushing depth of the pier.

The depth measuring unit of the present invention further includes a certain pulley to allow a partial rope to be wound around the fixed pulley. The fixed pulley is pivotally connected to a first support shaft, and the first support shaft is fastened in a box.

The box is fastened to one of the pier and the bridge and has a hole that allows the rope to hang freely and through. The metal components inside the box are coated with anti-rust oil to reduce the incidence of rust and protect all or part of the depth measurement, conversion and sensing units.

The depth measuring unit further has a straight pipe fixed to the pier, and the straight pipe blocks the impact of the water flow direction on the hammer body, and can guide the hammer body to descend along the pipe diameter, and relatively reduce the error value of the depth measurement.

The conversion unit comprises: a driving wheel and a driven wheel which are coupled to the fixed pulley and which are rotatable in the same direction. The driven wheel is pivotally connected to the second supporting shaft of the casing and is designed integrally with a screw. The screw locks into a cover plate disposed in the casing and contacts the light sensing unit, and supports the driven wheel to engage the driving wheel and maintain a 1:1 gear ratio.

The driving wheel is disposed on a wheel axle. One end of the wheel shaft is pivotally connected to the cover plate, and the other end is inserted into a connecting rod connecting the fixed pulley, and the connecting rod drives the driving wheel to rotate in the same direction as the fixed pulley.

The light sensing unit also has two metal sheets and an elastic body adhered to the optical fibers and located on both sides of the fiber Bragg grating, the elastic body enclosing the fiber Bragg grating, the optical fiber and the metal sheet. When the two metal sheets are fastened to a seat body provided in the casing, the elastic body is supported by the metal piece at a position substantially perpendicular to the screw. The elastic body receives the force of the screw, which not only protects the optical fiber from being damaged by external force, but does not affect the sensing function of the fiber Bragg grating on the grating pitch extension.

The light sensing unit further includes a spectrum analyzer, a light circulator, an optical isolator and an input light source. The input light source transmits light having a wavelength ranging from about 1310 nm to 1610 nm. The optical fiber enters the optical circulator through the optical isolator and is transferred to the fiber Bragg grating to induce reflection. The distance of the central wavelength drift is analyzed by the spectrum analyzer to obtain the measurement result of the pier scouring depth.

In order to make the objects, features, and advantages of the present invention more comprehensible, the following embodiments are illustrated in the accompanying drawings.

10‧‧‧Deep measurement unit

11‧‧‧Support frame

12‧‧‧ Hammer

13‧‧‧fasteners

14‧‧‧ rope

16‧‧‧ fixed pulley

18‧‧‧ Straight tube

20‧‧‧ cabinet

21‧‧‧ hole

22‧‧‧First support shaft

23‧‧‧ screw holes

24‧‧‧second support shaft

26‧‧‧ body

28‧‧‧ Cover

30‧‧‧Transfer unit

31‧‧‧ screw

32‧‧‧Drive wheel

34‧‧‧ linkage

36‧‧‧Axle

38‧‧‧ driven wheel

40‧‧‧Light sensing unit

41‧‧‧ fiber Bragg grating

42‧‧‧Optical fiber

43‧‧‧solid points

44‧‧‧metal pieces

46‧‧‧Fixed holes

48‧‧‧ Elastomers

50‧‧‧Spectrum Analyzer

52‧‧‧Light Circulator

54‧‧‧Optical isolator

56‧‧‧Input light source

60‧‧‧ Pier

62‧‧‧ Bridge

64‧‧‧Water flow direction

66‧‧‧ Riverbed

68‧‧‧ Scouring position

Fig. 1 is a configuration diagram of a preferred embodiment of a pier scouring depth sensor of the present invention.

Figure 2 is a layout view of the inside of the cabinet.

Figure 3 is a plan view of the elastomer.

Figure 4 is a diagram showing the state of use of the pier scouring depth sensor.

Figure 5 is a schematic diagram of a spectrum analysis table.

Please refer to Figures 1, 2 and 4 to illustrate a specific structure of a preferred embodiment of the bridge scouring depth sensor, comprising: a depth measuring unit 10 contacting the river bed 66, and a depth conversion into an axial displacement variation The conversion unit 30, and a light sensing unit 40 that detects the amount of axial displacement change using a fiber Bragg grating (abbreviated as FBG).

The pier scouring depth sensor of the present invention also has a box 20 that is fastened to a bridge 60 or a bridge 62 by one of a screw lock and a welding means. In the present embodiment, the box 20 is under the bridge 62, and has good airtightness, which can effectively prevent external humid air from penetrating into the box, and all or part of the depth measurement, conversion and sensing unit 10, 30 40 has a protective effect. In addition, the metal component inside the casing 20 is coated with anti-rust oil, which can reduce the incidence of rust and eliminate some error values, so that the sensing operation can be stably performed.

The depth measuring unit 10 has a hammer body 12, a rope 14 and a fixed pulley 16. The fixed pulley 16 is pivotally connected to a first support shaft 22 fastened to the casing 20, allowing a partial rope 14 to be wound around the fixed pulley 16. One end of the rope 14 is freely landed through a hole 21 formed in the casing 20 for attaching the hammer body 12.

When the weight of the hammer 12 acts on the rope 14, the fixed pulley 16 is pulled by the rope 14 to rotate on the first support shaft 22, and the support hammer 12 contacts the river bed 66 below the bridge 62 for the purpose of measuring the depth of the river bed 66.

The depth measuring unit 10 also has a straight tube 18 on which one side of the straight tube 18 is welded or locked. Each support frame 11 is similar to a Y-shaped design that is secured to the side of a bridge 60 by fasteners 13 such as screws or bolts that support the straight tube 18 generally parallel to the length of the bridge 60 and block the impact of the flow direction 64. Avoid excessive shaking of the hammer 12. The straight pipe 18 has its nozzle facing the hole 21 of the casing 20, and can guide the hammer 12 to descend along the fixed pipe diameter, and relatively reduce the error value of the depth measurement.

The conversion unit 30 has a driving wheel 32 and a driven wheel 38. The driving wheel 32 is disposed on an axle 36. One end of the axle 36 is pivotally connected to a cover plate 28, and the other end is inserted into a connecting rod 34. The connecting rod 34 is coupled to the fixed pulley 16 and can rotate in the same direction, and is responsible for the transmission of the rotational kinetic energy of the fixed pulley 16, and drives the axle 36 to rotate with the driving wheel 32. The driven wheel 38 has a longer axial length than the driving wheel 32. One side of the driven wheel 38 is pivotally connected to the second supporting shaft 24 of the casing 20, and the other side is integrally formed with a screw 31. The free end of the screw 31 is locked into a screw hole 23 formed in the cover plate 28, and the end of the screw 31 locked into the cover plate 28 is preferably in contact with the light sensing unit 40, and the driven wheel 38 is supported to maintain the meshing relationship with the driving wheel 32. .

The driven wheel 38 is longer than the drive wheel 32 in terms of axial length. The gear ratio of the active and driven wheels 32, 38 is maintained at 1:1, so that the driven wheel 38 and the fixed pulley 16 have the same rotation amplitude, and can continue to penetrate the screw hole 23 of the cover plate 28. Since the cover plate 28 is secured to the body 26 by the other fasteners 13, the screw 31 is displaced in a direction substantially perpendicular to the cover plate 28, and a certain pushing pressure is applied to the light sensing unit 40.

Next, as seen in FIG. 3, the light sensing unit 40 has an optical fiber 42 (also referred to as an optical fiber, originally known as Optical fiber), and the two metal sheets 44 are adhered to the optical fiber 42 by hot melt adhesive bonding. Defining the adhesion between the optical fiber 42 and the metal piece 44 is a firm point 43. The two solid points 43 are separated by a certain distance, and a fiber Bragg grating 41 is allowed to adhere to the portion of the optical fiber 42 between the two solid points 43 and reused. The silicone molding method forms an elastic body 48, and the optical fiber Bragg grating 41, the optical fiber 42 and the metal piece 44 are wrapped by the elastic body 48.

The metal piece 44 has two fixing holes 46, and any of the fixing holes 46 is passed through the other fasteners 13 shown in FIG. 2 for locking to the corresponding parts of the seat body 26. Thus, the elasticity of the metal piece 44 itself can improve the sensitivity measured by the light sensing unit 40.

Moreover, the elastic body 48 receives the pushing pressure of the screw 31, which can protect the optical fiber 42 from being easily broken by external force without affecting the sensing function of the fiber Bragg grating 41.

It is not difficult to understand from the first to fourth figures that the optical sensing unit 40 further includes an optical spectrum analyzer (OSA) 50, an optical circulator 52, an optical isolator 54 and an optical isolator 54. The light source 56 is input.

In the optical path architecture, the input light source 56 enters the optical circulator 52 through the optical isolator 54 via the optical fiber 42 using a C+L Band wideband source (BBS) having a wavelength range of about 1310 nm to 1610 nm. The first port (Port). The light source is switched from the first turn to the second turn of the optical circulator 52, and the fiber Bragg grating 41 outputted to the optical fiber 42 performs sensing. Since the light is reflected by the grating, the reflected center wave is transferred from the second to the third and output to the optical spectrum analyzer 50 for measurement analysis.

When the pier 60 is subjected to the flushing of the water flow direction 64, the drop in the height of the river bed 66 changes from the solid line position to the dashed flushing position 68. Under the effect that the weight is greater than the buoyancy, the hammer 12 is lowered to the flushing position 68, and the depth of the river bed 66 after flushing can be measured.

The depth detected by the hammer body 12 is converted into the elastic body 48 by the amount of change in the axial displacement of the screw 31 by the engagement relationship between the active and driven wheels 32, 38, causing the grating pitch of the fiber Bragg grating 41 to stretch. The depth value of the drop of the hammer body 12 can be detected by changing the wavelength of the center wave.

In the present embodiment, it is assumed that the material of the metal piece 44 is yttrium manganese steel, and the analysis table shown in Fig. 5 can be obtained. The vertical line of the analysis table represents the central wavelength (Central Wavelength), the unit is nanometer (nm); the horizontal line represents the depth (Depth), the unit is the meter (m), used to analyze the falling points of the real and the virtual two curves. Wherein, the real curve represents a nonlinear curve fitting, and the virtual curve represents a silicone manganese steel.

If the circumference of the fixed pulley 16 is about 0.2 meters, the pitch of each screw of the screw 31 is about 1 millimeter (millimetre, abbreviated as mm). In the present embodiment, the screw 31 is allowed to rotate about 20 turns to ensure that the fiber Bragg grating 41 receives the force of the screw 31 without breaking. Therefore, the elastic body 48 receives an allowable range of the displacement variation of the screw 31 of about 20 mm.

Considering a precise depth measurement unit every 0.2 meters, the center wavelength of the fiber Bragg grating 41 drifts by a distance of 0.3515 nm. Therefore, the total wavelength drift of the center wavelength in this embodiment is about 7.03 nm, and the measurement range of about 4 meters in total depth is achieved, which has the advantages of simplified structure, high sensitivity, and good stability.

In some embodiments, the pier scouring depth sensor or sheet metal 44 may be made of one of tantalum manganese steel, aluminum, medium carbon steel, or other metal materials.

10‧‧‧Deep measurement unit

11‧‧‧Support frame

12‧‧‧ Hammer

13‧‧‧fasteners

14‧‧‧ rope

16‧‧‧ fixed pulley

18‧‧‧ Straight tube

20‧‧‧ cabinet

21‧‧‧ hole

22‧‧‧First support shaft

23‧‧‧ screw holes

24‧‧‧second support shaft

26‧‧‧ body

28‧‧‧ Cover

30‧‧‧Transfer unit

31‧‧‧ screw

32‧‧‧Drive wheel

34‧‧‧ linkage

36‧‧‧Axle

38‧‧‧ driven wheel

40‧‧‧Light sensing unit

42‧‧‧Optical fiber

50‧‧‧Spectrum Analyzer

52‧‧‧Light Circulator

54‧‧‧Optical isolator

56‧‧‧Input light source

Claims (7)

A pier scouring depth sensor comprises: a depth measuring unit (10) having a hammer body (12) and a rope (14) connecting the hammer body (12), the rope (14) supporting the hammer body (12) Contacting the river bed (66) by gravity, a fixed pulley (16) for winding the rope (14), the fixed pulley (16) is pivotally connected to a first support shaft (22), and the first support shaft (22) is fastened In a box (20); a conversion unit (30) for measuring the depth of the river bed (66) by measuring the depth of the river bed (66), the conversion unit (30) comprising: a fixed pulley (16) And a driving wheel (32) that can rotate in the same direction and a driven wheel (38) that engages the driving wheel (32), the driven wheel (38) is pivotally connected to a second supporting shaft fastened to the casing (20) (24) and designed integrally with a screw (31); a light sensing unit (40) that is accessed by the screw (31), the light sensing unit (40) has an optical fiber (42) and a configuration In the fiber Bragg grating (41) of the optical fiber (42), light of a certain wavelength is allowed to be output to the fiber Bragg grating (41) via the optical fiber (42), and the fiber Bragg grating (41) receives the axial displacement of the screw (31) The amount of change caused by the grating spacing is extended for inspection Pier (60) scour. A pier scouring depth sensor according to claim 1, wherein the casing (20) is fastened to one of the pier (60) and the bridge (62), and has an allowable rope (14) to hang freely. Through the hole (21), the metal component inside the box (20) is coated with anti-rust oil to reduce the incidence of rust, and all or part of the depth measurement, conversion and sensing unit (10, 30, 40) Produce protection. The pier scouring depth sensor according to claim 2, wherein the depth measuring unit (10) further has a straight pipe (18) fixed to the pier (60), the straight pipe (18) blocking the flow direction of the water. (64) The impact on the hammer body (12) can guide the hammer body (12) to descend along the pipe diameter, and relatively reduce the error value of the depth measurement. The pier scouring depth sensor of claim 1, wherein the screw (31) is locked into a cover plate (28) disposed in the casing (20) to support the driven wheel (38). The drive wheel (32) maintains a 1:1 gear ratio. The bridge piercing depth sensor according to claim 4, wherein the driving wheel (32) is disposed on an axle (36), and one end of the axle (36) is pivotally connected to the cover plate (28), and the other end A connecting rod (34) of a coupling pulley (16) is inserted, and the driving wheel (32) is driven by the connecting rod (34) to rotate in the same direction as the fixed pulley (16). The bridge piercing depth sensor of claim 4, wherein the light sensing unit (40) further has two metal sheets (44) and an elastic body (48), and the metal sheets (44) are adhered. On the optical fiber (42) and on both sides of the fiber Bragg grating (41), the elastic body (48) encloses the fiber Bragg grating (41), the optical fiber (42) and the metal piece (44); when the two metal pieces (44) Fastened to a seat body (26) provided in the casing (20), the elastic body (48) being supported by the metal piece (44) at a position substantially perpendicular to the screw (31), the elastic body (48) The force of the receiving screw (31) can protect the optical fiber (42) from being broken by external force, but does not affect the sensing function of the fiber Bragg grating (41) with respect to the grating pitch extension. The bridge sensing depth sensor according to claim 1, wherein the light sensing unit (40) further comprises a spectrum analyzer (50), a light circulator (52), and an optical isolator (54). And an input light source (56), the input light source (56) transmits light having a wavelength range of about 1310 nm to 1610 nm, enters the optical circulator (52) through the optical isolator (54) via the optical fiber (42), and is transferred to the fiber Bragg grating. (41) The causal reflection effect is obtained by analyzing the distance of the central wavelength drift by the spectrum analyzer (50), and obtaining the measurement result of the scouring depth of the pier (60).