An optical fiber grating monitoring device and monitoring method for uneven settlement of road subgrades

Abstract

The present invention discloses a fiber Bragg grating monitoring device and a monitoring method for uneven settlement of roadbed. During the construction or maintenance of the roadbed, drill holes at key positions of the roadbed. After assembling the pre-buried protective housing, install a plurality of fiber Bragg grating strain sensors, strain installation components, fiber Bragg grating temperature sensors, a plurality of fiber Bragg grating inclination sensors, inclination installation components and a series connection line in the pre-buried protective housing. Insert the assembled above-mentioned functional fittings into the drilled holes, and then perform grouting treatment; the fiber Bragg grating strain sensors can real-time sense the settlement changes of the roadbed; while the series-connected fiber Bragg grating temperature sensors are used for temperature compensation, they can monitor the temperature changes at the pre-buried locations; the fiber Bragg grating inclination sensors monitor the changes in the inclination angles of the locations where they are located, and the series connection line transmits the signals to the fiber Bragg grating demodulation system. This fiber Bragg grating demodulation system is used for data acquisition, processing and extracting the information of the settlement amount, drawing the roadbed settlement curve and analyzing the settlement trend.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber Bragg grating sensors, and particularly relates to a fiber Bragg grating monitoring device and a monitoring method for uneven settlement of road subgrades. Background Technique

[0002] Uneven settlement of subgrades is a common phenomenon in road engineering construction and operation, especially serious in sections such as backfill sections, high and steep slopes, and complex geological conditions. Its uniformity directly affects the safety and comfort of roads. Especially for key sections such as expressways, bridges, and tunnels, the settlement monitoring of subgrades is particularly important. In recent years, with large-scale engineering projects gradually entering the maintenance period, various uneven settlement accidents occur from time to time, causing huge losses to people's lives and property. Conventional subgrade settlement monitoring methods mainly include leveling measurement method, GPS measurement method, visual recognition, remote sensing monitoring, etc. However, these methods have problems such as limited accuracy, high cost, complex operation, poor real-time performance, and poor durability. Therefore, it is necessary to propose a fiber Bragg grating monitoring device and a monitoring method for uneven settlement of road subgrades to conduct long-term, real-time, online, efficient, and high-precision monitoring of subgrades.

[0003] A fiber Bragg grating sensor is a wavelength-modulated fiber sensor. Its basic working principle is that light enters the grating area through the fiber. Through the change of external quantities, multiple parameters of light in the grating area are changed, such as wavelength, intensity, amplitude, frequency, etc., so as to measure the external quantities and realize data transmission. The fiber Bragg grating sensor has the characteristics of strong anti-interference ability, not being affected by electromagnetic interference, high measurement accuracy, easy distributed networking, and good environmental adaptability. The fiber Bragg grating sensor is a safety-type product and is widely used in remote, online, real-time, and intelligent monitoring of mines, bridges, tunnels, deep foundation pits, high slopes, prefabricated buildings, etc.

[0004] Currently, manufacturers engaged in fiber Bragg grating sensing technology at home and abroad generally encapsulate the substrate in the way of epoxy resin, fiber Bragg grating, and sensing matrix. The epoxy resin glue is only combined with the sensing matrix through physical bonding, and the bonding method is not firm. Moreover, the epoxy resin glue is extremely easy to damage and fall off in high-temperature, high-humidity, strong ultraviolet, and corrosive environments, and further improvement is needed. Summary of the Invention

[0005] The present invention provides a fiber Bragg grating monitoring device and a monitoring method for uneven settlement of road subgrades, which can solve the problems of limited accuracy, high cost, complex installation and use operation, poor real-time performance, and poor durability existing in the existing monitoring methods.

[0006] To solve the above problems, the technical solutions provided by the present invention are as follows:

[0007] An embodiment of the present invention provides a fiber Bragg grating monitoring device for uneven settlement of a road subgrade, which includes a pre-buried protective housing (1), a fiber Bragg grating demodulation system (8), and a power supply unit (9). The pre-buried protective housing (1) is used to be buried into a drilled hole at a key part of the subgrade. The pre-buried protective housing (1) includes a hollow tapered tube (101), a plurality of intermediate mounting tubes (102), a terminal mounting tube (103), a tee connection seat (106), and a sealing cover (109) connected in sequence. A threaded connection fixing sleeve (104) and a plurality of locking washers (105) are arranged between the terminal mounting tube (103) and the tee connection seat (106). One end interface of the sealing cover (109) is connected with a plurality of locking joints (110), and an inclination protective cover (107) is connected to the middle interface of the tee connection seat (106).

[0008] A plurality of fiber Bragg grating strain sensors (2), strain mounting components (3), fiber Bragg grating temperature sensors (4), and a series connection line (10) are installed in the hollow tapered tube (101), the plurality of intermediate mounting tubes (102), and the terminal mounting tube (103). A plurality of fiber Bragg grating inclination sensors (5), inclination mounting components (6), and the series connection line (10) are installed in the inclination protective cover (107) and the inclination protection cover (108). The series connection line (10) is electrically connected to the fiber Bragg grating strain sensor (2), the fiber Bragg grating temperature sensor (4), and the fiber Bragg grating inclination sensor (5). The end of the series connection line (10) is a quick plug, and the quick plug is electrically connected to the fiber Bragg grating demodulation system (8). The fiber Bragg grating demodulation system (8) is also electrically connected to the power supply unit (9).

[0009] According to an optional embodiment of the present invention, the strain mounting component (3) has a cylindrical structure, and its outer diameter is closely attached to the inner wall of the pre-buried protective housing (1). The strain mounting component (3) includes a hollow mounting seat (301), a transition mounting seat (302), a terminal mounting seat (303), a locking square pin (304), and a fiber guiding tube (305).

[0010] The strain mounting assembly (3) is axially provided with third-party grooves (301-1), fourth-party grooves (302-1) and fifth-party grooves (303-1) of the same shape along the inner diameter; one end of the hollow mounting seat (301) along the third-party groove (301-1) is a sealing circular plate (301-2), and a hollow column cavity (301-3) is arranged inwardly of the sealing circular plate (301-2); one end of the optical fiber guiding tube (305) is located in the hollow column cavity (301-3), and the other end is fixedly connected to one end of the third-party groove (301-1); a mortise-tenon connection is provided between the other end of the hollow mounting seat (301) and the transition mounting seat (302); the locking square pin (304) has a square structure, and both ends of the locking square pin (304) are tangent to the outer diameter of the hollow mounting seat (301). While the locking square pin (304) locks the hollow mounting seat (301) and the transition mounting seat (302), it can serve as a limiting rod for the series connection line (10); one end of the end mounting seat (303) is mortise-tenon connected to the transition mounting seat (302), and the other end of the end mounting seat (303) is a planar structure.

[0011] According to an optional embodiment of the present invention, the thread connection fixing sleeve (104) is threadedly connected to the end mounting tube (103) and presses against the strain mounting assembly (3); the locking washer (105) and the thread connection fixing sleeve (104) are used to cooperate to limit the rotation of the end mounting tube (103) and the thread connection fixing sleeve (104); the tee connection seat (106) and the thread connection fixing sleeve (104) are fixed by the locking washer (105) to limit their relative rotation;

[0012] The fiber optic grating inclination sensor (5), the inclination mounting assembly (6), and the series connection line (10) are installed in the inclination protection cover (107); the series connection line (10) successively connects a plurality of the fiber optic grating strain sensors (2), a plurality of the fiber optic grating temperature sensors (4), the optical fiber guiding tube (305), and a plurality of the fiber optic grating inclination sensors (5) in series starting from the end of the tee connection seat (106), and the series connection line (10) also passes through a locking joint (110) installed in a third threaded hole (109-2) opened on the sealing cover (109).

[0013] According to an optional embodiment of the present invention, the hollow tapered tube (101) is a hollow tubular shape, one end of the hollow tapered tube (101) is a hollow taper (101-1), the hollow tapered tube (101) is connected to the intermediate mounting tube (102) by a thread, the intermediate mounting tube (102) is connected to the end mounting tube (103) by a thread, and a plurality of intermediate mounting tubes (102) are connected to each other by a thread;

[0014] The wire-to-wire connection fixing sleeve (104) is a hollow straight-through tubular structure. Third external threads (104-1) are provided at both ends of the wire-to-wire connection fixing sleeve (104), and a spline groove (104-2) is provided in the middle thereof; a first square groove (103-2) is provided at the meshing end of the end mounting pipe (103) and the wire-to-wire connection fixing sleeve (104) for mounting the limiting piece (105-1) of the locking washer (105). After positioning, a plurality of the fixing pieces (105-2) on the outer diameter of the locking washer (105) are bent into the spline groove (104-2).

[0015] According to an optional embodiment of the present invention, the tee connection seat (106) is a hollow right-angle tee tubular structure; a third internal thread (106-1) is provided at the middle interface of the tee connection seat (106). A second square groove (106-2) is opened at the meshing end of the tee connection seat (106) and the wire-to-wire connection fixing sleeve (104) for mounting the limiting piece (105-1) of the locking washer (105); a second threaded through hole (106-3) is provided at the other end of the tee connection seat (106), and the second threaded through hole (106-3) meshes with a second threaded hole (109-1) opened in the sealing cover (109). The sealing cover (109) is a cylindrical structure, and the bottom of the barrel of the sealing cover (109) is a polygonal structure.

[0016] According to an optional embodiment of the present invention, the bottom of the inclination protective cover (107) is a hollow pipe (107-1), and a fourth external thread (107-2) is provided at the end of the hollow pipe (107-1). The fourth external thread (107-2) meshes with the third internal thread (106-1) at the middle interface of the tee connection seat (106);

[0017] A hollow barrel-shaped cover (107-3) is provided at the upper end of the hollow tube (107-1), the hollow barrel-shaped cover (107-3) and the hollow tube (107-1) are spatially connected, the hollow barrel-shaped cover (107-3) has no upper cover, and a plurality of inclination mounting plates (107-4) are provided along the axial section position of the side surface thereof, the plurality of inclination mounting plates (107-4) are used to fix the inclination mounting assembly (6), the inclination mounting assembly (6) is used to fix the fiber grating inclination sensor (5), and can adjust the front, rear, left, and right inclination of the fiber grating inclination sensor (5). The top of the hollow barrel-shaped cover (107-3) is provided with a first threaded hole (107-5), and the first threaded hole (107-5) is used to fix the tilt protection cover (108); the upper part of the tilt protection cover (108) is a circular plate (108-1), and the lower part is an open circular fan plate (108-2), and the circular plate (108-1) is provided with a first threaded through hole (108-3), and the first threaded through hole (108-3) is engaged with the first threaded hole (107-5) to seal the tilt protection cover (107) and the tilt protection cover (108).

[0018] The embodiment of the present invention further provides a fiber Bragg grating monitoring method for uneven settlement of a roadbed, wherein the fiber Bragg grating monitoring method is implemented by a fiber Bragg grating monitoring device for uneven settlement of a roadbed as in the above embodiment, wherein the fiber Bragg grating monitoring method comprises the following steps:

[0019] Step S1, during the roadbed construction or maintenance process, holes are drilled at key locations of the roadbed, and after assembling the hollow pointed cone tube (101), a plurality of intermediate mounting tubes (102), an end mounting tube (103), a three-way connection seat (106) and a sealing cover (109) of the embedded protective housing (1), the hollow mounting seat (301), the transition mounting seat (302), the end mounting seat (303), the locking square pin (304) and the fiber guide tube (305) of the strain mounting assembly (3) are assembled;

[0020] Step S2, installing a fiber Bragg grating strain sensor (2), a strain mounting assembly (3), a fiber Bragg grating temperature sensor (4) and a series connection line (10) in the hollow cone tube (101), a plurality of intermediate mounting tubes (102) and a terminal mounting tube (103), and installing a plurality of fiber Bragg grating inclination sensors (5), an inclination mounting assembly (6) and a series connection line (10) in the inclination protection cover (107) and the inclination protection cover (108); the series connection line (10) is electrically connected to the fiber Bragg grating strain sensor (2), the fiber Bragg grating temperature sensor (4) and the fiber Bragg grating inclination sensor (5); the assembled functional accessories are inserted into a key part of a roadbed borehole, and grouting treatment is performed after the insertion;

[0021] Step S3: The end of the serial connection line (10) is a quick plug, which is electrically connected to the fiber Bragg grating demodulation system (8). The fiber Bragg grating demodulation system (8) is also electrically connected to the power supply unit (9). The fiber Bragg grating strain sensor (2) is used to sense the change of subgrade settlement in real time. The series-connected fiber Bragg grating temperature sensor (4) can monitor the temperature change at the embedded location while serving as temperature compensation. The fiber Bragg grating inclination sensor (5) monitors the change of the inclination angle at the location, and is used to check whether the installation angle and position of the device are correct, and whether there is abnormal inclination or damage during operation. The serial connection line (10) transmits the signal to the fiber Bragg grating demodulation system (8). The fiber Bragg grating demodulation system (8) collects, processes and extracts the information of the settlement amount, draws the subgrade settlement curve, analyzes the settlement trend. The fiber Bragg grating demodulation system (8) monitors the data according to the preset data quality standards and rules. Once data anomalies or exceeding the preset range are found, an alarm will be issued immediately. The fiber Bragg grating demodulation system (8) provides a scientific basis for the safe operation and maintenance of the road. The data can also be sent to the remote monitoring center and the mobile APP for accident early warning in a timely manner.

[0022] Compared with the prior art, the embodiment of the present invention provides a fiber Bragg grating monitoring device and method for uneven settlement of road subgrade, and has the following beneficial effects:

[0023] (1). Chinese Patent CN112230327A discloses "a fully glass encapsulation device and encapsulation method for fiber Bragg gratings". Based on this patented technology, the present invention further innovatively develops a new type of fiber Bragg grating sensor substrate. On the basis of the characteristics of strong anti-interference ability, no electromagnetic interference, high measurement accuracy, easy distributed networking, and good environmental adaptability of fiber Bragg grating sensors, the problems of poor durability and stability of current fiber sensors are solved.

[0024] (2). Based on the new type of fiber Bragg grating sensor substrate, the new type of fiber Bragg grating sensor developed by the present invention uses the fiber Bragg grating sensing principle to achieve high-precision measurement of subgrade settlement. The substrate can monitor parameters such as soil deformation, inclination, and temperature respectively, and the monitoring data are independently monitored without interference. The present invention can establish a dynamic model based on the initial surveying and mapping data to display its changes in real time; setting an alarm threshold can achieve segmented early warning, and the monitoring data can be wirelessly transmitted in real time to achieve remote and local synchronous early warning, which can effectively avoid accidents. With the increase of the layout range and the reduction of the layout distance, the monitoring accuracy is higher; through the remote monitoring center, centralized management and analysis of data are realized, reducing the complexity and error of manual operation.

[0025] (3) The monitoring device of the present invention is simply and efficiently arranged, applicable to the monitoring of newly built and existing roadbeds, not affected by construction, without causing damage to the existing roadbed. It uses optics for monitoring, with low energy consumption. Using a micro solar panel or a micro wind power generator, and supporting a UPS power supply can meet the usage requirements, without the need for separate wiring. Compared with traditional measurement methods, the device of the present invention has a simple structure, low cost, and is easy to promote and apply.

[0026] (4) The strain part of the monitoring device of the present invention is arranged inside the roadbed for real-time sensing of the settlement changes of the roadbed; the monitoring device is installed inside an elastic metal rod, in close contact with the outer elastic metal rod. The outer elastic metal tube is grouted with the soil, and can accurately monitor the changes of soil strain, inclination, temperature, etc. The sensors in the monitoring device are modularly installed, with convenient and efficient installation and easy maintenance and replacement. The optical fiber of the monitoring device is scientifically and reasonably arranged, which can effectively reduce the loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic structural diagram of the embedded protective shell of a fiber Bragg grating monitoring device for uneven settlement of a roadbed provided by an embodiment of the present application.

[0029] Figure 2 It is a schematic internal structure diagram of the embedded protective shell of a fiber Bragg grating monitoring device for uneven settlement of a roadbed provided by an embodiment of the present application.

[0030] Figure 3 and Figure 4 It is a schematic layout structure diagram of the functional components in the integrated protective box provided by an embodiment of the present application.

[0031] Figure 5 It is a schematic structural diagram of the hollow tapered tube of the embedded protective shell of a fiber Bragg grating monitoring device for uneven settlement of a roadbed provided by an embodiment of the present application.

[0032] Figure 6 It is a schematic structural diagram of the middle installation tube of the embedded protective shell of a fiber Bragg grating monitoring device for uneven settlement of a roadbed provided by an embodiment of the present application.

[0033] Figure 7 It is a schematic structural diagram of the end installation tube of the embedded protective shell of a fiber Bragg grating monitoring device for uneven settlement of a roadbed provided by an embodiment of the present application.

[0034] Figure 8 Schematic diagram of the tee connection seat structure of the embedded protective housing of a fiber Bragg grating monitoring device for uneven settlement of roadbed provided by an embodiment of the present application.

[0035] Figure 9 Schematic diagram of the inclination protection cover structure of the embedded protective housing of a fiber Bragg grating monitoring device for uneven settlement of roadbed provided by an embodiment of the present application.

[0036] Figure 10 Schematic diagram of the inclination protection cover structure of the embedded protective housing of a fiber Bragg grating monitoring device for uneven settlement of roadbed provided by an embodiment of the present application.

[0037] Figure 11 Schematic diagram of the seal cover structure of the embedded protective housing of a fiber Bragg grating monitoring device for uneven settlement of roadbed provided by an embodiment of the present application. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0039] As Figure 1 、 Figure 2 、 Figure 3 and Figure 4 shown, an embodiment of the present invention provides a fiber Bragg grating monitoring device for uneven settlement of roadbed, including an embedded protective housing 1, a fiber Bragg grating demodulation system 8, and a power supply unit 9. The embedded protective housing 9 is made of elastic family material and is subjected to multi-layer anti-corrosion treatment both inside and outside. After the embedded protective housing is assembled, a sealed hollow space can be formed. The embedded protective housing 1 is used to be buried in the drilled holes at key parts of the roadbed. The embedded protective housing 1 includes a hollow tapered tube 101, a plurality of intermediate installation tubes 102, a terminal installation tube 103, a tee connection seat 106, and a seal cover 109 that are connected in sequence. A stud connection fixing sleeve 104 and a plurality of locking washers 105 are arranged between the terminal installation tube 103 and the tee connection seat 106; one end interface of the seal cover 109 is connected with a plurality of locking joints 110, and the middle interface of the tee connection seat 106 is connected with an inclination protection cover 107.

[0040] A hollow tapered tube 101, a plurality of intermediate mounting tubes 102, and an end mounting tube 103 are installed with a plurality of fiber Bragg grating strain sensors 2, a strain mounting assembly 3, a fiber Bragg grating temperature sensor 4, and a series connection line 10. A plurality of fiber Bragg grating inclination sensors 5, an inclination mounting assembly 6, and a series connection line 10 are installed inside an inclination protective cover 107 and an inclination protection cover 108; the series connection line 10 is electrically connected to the fiber Bragg grating strain sensor 2, the fiber Bragg grating temperature sensor 4, and the fiber Bragg grating inclination sensor 5; the end of the series connection line 10 is a quick plug, and the quick plug is electrically connected to a fiber Bragg grating demodulation system 8, and the fiber Bragg grating demodulation system 8 is also electrically connected to a power supply unit 9.

[0041] The fiber Bragg grating strain sensor 2 is used to sense the settlement change in real time. The series-connected fiber Bragg grating temperature sensor 4 can monitor the temperature change at the embedding location while compensating for temperature. The fiber Bragg grating inclination sensor 5 parallel to the axis of the strain mounting assembly 3 monitors the change in the inclination angle of the location where it is located. An internal temperature sensor can monitor the external temperature change while compensating for temperature. The fiber Bragg grating inclination sensor 5 perpendicular to the axis of the strain mounting assembly 3 is used to check whether the installation angle and position of the device are correct, and whether there is abnormal inclination or damage during operation; the series connection line 10 transmits the signal to the fiber Bragg grating demodulation system 8. The fiber Bragg grating demodulation system 9 collects and processes the data to extract the information of the settlement amount, draws the subgrade settlement curve, analyzes the settlement trend. The system monitors the data according to the preset data quality standards and rules. Once data anomalies or exceeding the preset range are found, the system will immediately issue an alarm, providing a scientific basis for the safe operation and maintenance of the road; the data can also be sent to a remote monitoring center and a mobile APP for timely accident warning.

[0042] Such as Figure 3 And Figure 4As shown in the figure, multiple unassembled and scattered fiber Bragg grating strain sensors 2, multiple fiber Bragg grating temperature sensors 4, multiple fiber Bragg grating inclination sensors 5, a fiber Bragg grating demodulation system 8, a power supply unit 9, and a series connection line 10 are placed in an integrated protection box assembly 7. The integrated protection box assembly 7 includes an upper box 701, a lower box 702, and a shock-absorbing filler 703. The shock-absorbing filler 703 is a flexible material. The lower box 702 is provided with a lower box bottom layer 70301, a lower box intermediate layer 70302, and a lower box covering layer 70303. The upper box 701 is provided with an upper box bottom layer 70304, an upper box intermediate layer 70305, and an upper box covering layer 70306. The lower box bottom layer 70301 and the upper box bottom layer 70304 are flat surfaces; the lower box intermediate layer 70302 is provided with first special-shaped grooves 70302-01 with different depths for placing multiple fiber Bragg grating strain sensors 2, multiple fiber Bragg grating temperature sensors 4, multiple fiber Bragg grating inclination sensors 5, a fiber Bragg grating demodulation system 8, a power supply unit 9, and a series connection line 10. The series connection line 10 between the sensors is placed in the lower box, and the extended series connection line 10 for the sensor to enter and exit is placed in the upper box intermediate layer 70305. The upper box intermediate layer 70305 is provided with second special-shaped grooves 70305-01 with different depths for placing the power supply unit 9 and the extended series connection line 10 for external extension of the sensor. The lower box covering layer 70303 and the upper box covering layer 70306 are both grooves for the extended series connection line 10 to run through.

[0043] As Figure 2 shown, the strain installation component 3 is a cylindrical structure, and its outer diameter is closely attached to the inner wall of the embedded protection shell 1; the strain installation component 3 includes a hollow installation seat 301, a transition installation seat 302, an end installation seat 303, a locking square pin 304, and a fiber guiding tube 305; the strain installation component 3 is provided with third square grooves 301-1, fourth square grooves 302-1, and fifth square grooves 303-1 with the same shape along the inner diameter along the axis; one end of the hollow installation seat 301 along the third square groove 301-1 is a sealing circular plate 301-2, and a hollow column cavity 301-3 is arranged inwardly of the sealing circular plate 301-2; one end of the fiber guiding tube 305 is located in the hollow column cavity 301-3, and the other end is fixedly connected to one end of the third square groove 301-1; the other end of the hollow installation seat 301 and the transition installation seat 302 are connected by a mortise and tenon joint; the locking square pin 304 is a cubic structure, and both ends of the locking square pin 304 are tangent to the outer diameter of the hollow installation seat 301. While the locking square pin 304 locks the hollow installation seat 301 and the transition installation seat 302, it can serve as a limiting rod for the series connection line 10; one end of the end installation seat 303 is connected to the transition installation seat 302 by a mortise and tenon joint, and the other end of the end installation seat 303 is a flat surface structure.

[0044] As Figure 1As shown, the threaded connection end of the wire-to-wire connection fixing sleeve 104 is installed with the end installation pipe 103 and presses against the strain installation assembly 3; the lock washer 105 and the wire-to-wire connection fixing sleeve 104 are used to cooperate to limit the rotation of the end installation pipe 103 and the wire-to-wire connection fixing sleeve 104; the tee connection seat 106 and the wire-to-wire connection fixing sleeve 104 are fixed by the lock washer 105 to limit their relative rotation; the middle interface of the tee connection seat 106 is threadedly connected to the inclination protection cover 107 and the inclination protection cap 108.

[0045] The fiber Bragg grating inclination sensor 5, the inclination installation assembly 6, and the series connection line 10 are installed in the inclination protection cover 107; the series connection line 10 successively connects a plurality of fiber Bragg grating strain sensors 2, a plurality of fiber Bragg grating temperature sensors 4, the fiber guiding tube 305, and a plurality of fiber Bragg grating inclination sensors 5 starting from the end of the tee connection seat 106, and the series connection line 10 also passes through the locking joint 110 installed in the third threaded hole 109-2 opened on the sealing cover 109, for reference Figure 11 .

[0046] As Figure 5 , Figure 6 and Figure 7 shown, the hollow tapered tube 101 is a hollow tubular structure, one end of the hollow tapered tube 101 is a hollow taper 101-1, the hollow tapered tube 101 is connected to the middle installation tube 102 by threads, the middle installation tube 102 is connected to the end installation tube 103 by threads, and a plurality of middle installation tubes 102 are connected to each other by threads.

[0047] One end of the hollow tapered tube 101 in this embodiment is provided with a hollow taper 101-1, the other end of the hollow tapered tube 101 is provided with a first external thread 101-2, one end of the middle installation tube 102 is provided with a first internal thread 102-1, and the other end is provided with a second external thread 102-2. The first internal thread 102-1 of the leftmost middle installation tube 102 and the first external thread 101-2. The first internal thread 102-1 of one middle installation tube 102 meshes with the second external thread 102-2 of another adjacent middle installation tube 102. The second external thread 102-2 of the rightmost middle installation tube 102 meshes with the second internal thread 103-1 of the end installation tube 103. Both ends of the end installation tube 103 are provided with a second internal thread 103-1, and one end meshes with the third external thread 104-1 of the wire-to-wire connection fixing sleeve 104.

[0048] As Figure 2As shown, the thread connection fixing sleeve 104 is a hollow straight tubular structure, and a third external thread 104-1 is provided at both ends of the thread connection fixing sleeve 104, and a spline groove 104-2 is provided in the middle; the end mounting tube 103 and the thread connection fixing sleeve 104 are engaged with the first square groove 103-2, which is used to install the limiting plate 105-1 of the locking washer 105, and the multiple fixing plates 105-2 on the outer diameter of the locking washer 105 are bent into the spline groove 104-2 after positioning.

[0049] like Figure 8 As shown, the three-way connecting seat 106 is a hollow right-angle three-way tubular structure; the middle interface of the three-way connecting seat 106 is provided with a third internal thread 106-1, and the engaging end of the three-way connecting seat 106 and the threaded connection fixing sleeve 104 is provided with a second square groove 106-2 for installing the limiting plate 105-1 of the locking washer 105; the other end of the three-way connecting seat 106 is provided with a second threaded through hole 106-3, and the second threaded through hole 106-3 is engaged with the second threaded hole 109-1 provided in the sealing cover 109, and the sealing cover 109 is a cylindrical structure, and the barrel bottom of the sealing cover 109 is a polygonal structure.

[0050] like Figure 9 As shown, the bottom of the inclination protection cover 107 is a hollow tube 107-1, and the end of the hollow tube 107-1 is provided with a fourth external thread 107-2, which is engaged with the third internal thread 106-1 of the middle interface of the three-way connecting seat 106. A hollow barrel-shaped cover 107-3 is provided at the upper end of the hollow tube 107-1, and the hollow barrel-shaped cover 107-3 and the hollow tube 107-1 are connected in space. The hollow barrel-shaped cover 107-3 has no upper cover, and a plurality of inclination mounting plates 107-4 are provided along the axial section position of the side thereof. The plurality of inclination mounting plates 107-4 are used to fix the inclination mounting assembly 6, and the inclination mounting assembly 6 is used to fix the fiber grating inclination sensor 5, and can adjust the front, rear, left and right positions of the fiber grating inclination sensor 5. Right tilt angle; a first threaded hole 107-5 is provided on the top of the hollow barrel-shaped cover 107-3, and the first threaded hole 107-5 is used to fix the tilt protection cover 108; the upper part of the tilt protection cover 108 is a circular plate 108-1, and the lower part thereof is an open circular fan plate 108-2, and the circular plate 108-1 is provided with a first threaded through hole 108-3, and the first threaded through hole 108-3 is engaged with the first threaded hole 107-5 to seal the tilt protection cover 107 and the tilt protection cover 108.

[0051] In one embodiment, the locking washer 105 can be replaced by a connecting pin, a mortise and tenon, a threaded fixation, etc. In one embodiment, the fiber guide tube 305 can be replaced by a flexible corrugated tube, a pipe clamp, etc. In one embodiment, the power supply unit 9 can be replaced by a solar panel, a wind turbine, a UPS power supply, or a combination of these types.

[0052] An embodiment of the present invention further provides a fiber Bragg grating monitoring method for uneven settlement of a road subgrade. This fiber Bragg grating monitoring method is implemented by a fiber Bragg grating monitoring device for uneven settlement of a road subgrade as described in the above embodiment. Among them, the fiber Bragg grating monitoring method includes the following steps:

[0053] Step S1, during the construction or maintenance of the subgrade, drill holes at key parts of the subgrade. After assembling the hollow tapered tube 101, multiple intermediate mounting tubes 102, end mounting tube 103, tee connection seat 106 and sealing cover 109 of the embedded protective shell 1, and after assembling the hollow mounting seat 301, transition mounting seat 302, end mounting seat 303, locking square pin 304 and fiber guiding tube 305 of the strain mounting assembly 3; preferably, the hollow mounting seat 301, transition mounting seat 302 and end mounting seat 303 are assembled by mortise and tenon joints.

[0054] Step S2, install the fiber Bragg grating strain sensor 2, strain mounting assembly 3, fiber Bragg grating temperature sensor 4 and series connection line 10 in the hollow tapered tube 101, multiple intermediate mounting tubes 102 and end mounting tube 103, and install multiple fiber Bragg grating inclination sensors 5, inclination mounting assembly 6 and series connection line 10 in the inclination protection cover 107 and inclination protection cap 108; the series connection line 10 is electrically connected to the fiber Bragg grating strain sensor 2, fiber Bragg grating temperature sensor 4 and fiber Bragg grating inclination sensor 5, and insert the assembled above-mentioned functional fittings into the drilled holes at key parts of the subgrade, and perform grouting treatment after insertion. In this embodiment, multiple fiber Bragg grating strain sensors, strain mounting assemblies, fiber Bragg grating temperature sensors, multiple fiber Bragg grating inclination sensors, inclination mounting assemblies and series connection lines are installed in the embedded protective shell; the counter-thread connection fixing sleeve in the embedded protective shell presses against the strain mounting assembly, insert the assembled above-mentioned functional fittings into the drilled holes, and perform grouting treatment after insertion.

[0055] Step S3: The end of the series connection line 10 is a quick plug, which is electrically connected to the fiber Bragg grating demodulation system 8. The fiber Bragg grating demodulation system 8 is also electrically connected to the power supply unit 9. The fiber Bragg grating strain sensor 2 is used to sense the change of subgrade settlement in real time. While the series-connected fiber Bragg grating temperature sensor 4 is used for temperature compensation, it can also monitor the temperature change at the embedded location. The fiber Bragg grating inclinometer 5 monitors the change of the inclination angle at the location, which is used to check whether the installation angle and position of the device are correct, and whether there is abnormal inclination or damage during operation. The series connection line 10 transmits the signal to the fiber Bragg grating demodulation system 8. The fiber Bragg grating demodulation system 8 collects, processes, and extracts the information of the settlement amount, draws the subgrade settlement curve, and analyzes the settlement trend. The fiber Bragg grating demodulation system 8 monitors the data according to the preset data quality standards and rules. Once it finds that the data is abnormal or exceeds the preset range, it will immediately issue an alarm. The fiber Bragg grating demodulation system 8 provides a scientific basis for the safe operation and maintenance of the road. The data can also be sent to the remote monitoring center and the mobile phone APP for timely accident warning.

[0056] Preferably, step S2 further includes: taking out a plurality of fiber Bragg grating strain sensors 2, a plurality of fiber Bragg grating temperature sensors 4, a plurality of fiber Bragg grating inclinometers 5, a fiber Bragg grating demodulation system 8, a power supply unit 9, and a series connection line 10 placed in the integrated protection box assembly 7. Passing a plurality of fiber Bragg grating strain sensors 2 and a plurality of fiber Bragg grating temperature sensors 4 through the thread connection fixing sleeve 104, a plurality of lock washers 105, and the tee connection seat 106, and then fixing them to the strain installation component 3. The thread connection fixing sleeve 104 presses against the strain installation component 3. The lock washer 105 locks the thread connection fixing sleeve 104 and connects the tee connection seat 106. The lock washer 105 is also used to lock the tee connection seat 106 and fix the inclination protection cover 107. Pull out a plurality of fiber Bragg grating inclinometers 5 from the tee connection seat 106 and install them into the inclination protection cover 107, and install the inclination protection cover 108. Extend the series connection line 10 through the sealing cover 109 and a plurality of locking joints 110, and use a plurality of locking joints to fix it to the sealing cover 109.

[0057] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention; those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope defined by the claims.

Claims

1. An optical fiber grating monitoring device for uneven settlement of road subgrade, characterized in that, It includes a pre-embedded protective housing, a fiber Bragg grating demodulation system, and a power supply unit. The pre-embedded protective housing is used to be buried in the drilled holes at the key parts of the roadbed. The pre-embedded protective housing includes a hollow tapered tube, a plurality of intermediate mounting tubes, a terminal mounting tube, a tee connection seat, and a sealing cover connected in sequence. A thread connection fixing sleeve and a plurality of lock washers are arranged between the terminal mounting tube and the tee connection seat. One end interface of the sealing cover is connected with a plurality of locking joints, and an inclination protective cover is connected to the middle interface of the tee connection seat. A plurality of fiber Bragg grating strain sensors, strain mounting components, fiber Bragg grating temperature sensors, and series connection lines are installed in the hollow tapered tube, the plurality of intermediate mounting tubes, and the terminal mounting tube. A plurality of fiber Bragg grating inclination sensors, inclination mounting components, and the series connection lines are installed in the inclination protective cover and the inclination protection cover. The series connection line is electrically connected to the fiber Bragg grating strain sensor, the fiber Bragg grating temperature sensor, and the fiber Bragg grating inclination sensor. The end of the series connection line is a quick plug, and this quick plug is electrically connected to the fiber Bragg grating demodulation system. The fiber Bragg grating demodulation system is also electrically connected to the power supply unit. The strain mounting component is of a cylindrical structure, and its outer diameter is closely attached to the inner wall of the pre-embedded protective housing. The strain mounting component includes a hollow mounting seat, a transition mounting seat, a terminal mounting seat, a locking square pin, and a fiber guiding tube. The strain mounting component is provided with a third square groove, a fourth square groove, and a fifth square groove of the same shape along the inner diameter along the axis. One end of the hollow mounting seat along the third square groove is a sealing circular plate, and a hollow column cavity is arranged inwardly of the sealing circular plate. One end of the fiber guiding tube is located in the hollow column cavity, and the other end is fixedly connected to one end of the third square groove. The connection between the other end of the hollow mounting seat and the transition mounting seat is a mortise and tenon connection. The locking square pin is of a cubic structure, and both ends of the locking square pin are tangent to the outer diameter of the hollow mounting seat. While the locking square pin locks the hollow mounting seat and the transition mounting seat, it can serve as a limiting rod for the series connection line. One end of the terminal mounting seat is connected to the transition mounting seat by a mortise and tenon connection, and the other end of the terminal mounting seat is a planar structure.

2. The fiber Bragg grating monitoring device for uneven settlement of road subgrade according to claim 1, characterized in that, The thread connection fixing sleeve is threadedly connected to the terminal mounting tube and presses against the strain mounting component. The lock washer and the thread connection fixing sleeve are used to cooperate to limit the rotation of the terminal mounting tube and the thread connection fixing sleeve. The tee connection seat and the thread connection fixing sleeve are fixed by the lock washer to limit their relative rotation. The fiber Bragg grating inclination sensor, the inclination mounting component, and the series connection line are installed in the inclination protective cover. The series connection line successively connects a plurality of the fiber Bragg grating strain sensors, a plurality of the fiber Bragg grating temperature sensors, the fiber guiding tube, and a plurality of the fiber Bragg grating inclination sensors starting from the end of the tee connection seat. The series connection line also passes through the locking joint installed in the third threaded hole opened on the sealing cover.

3. The fiber Bragg grating monitoring device for uneven settlement of road subgrade according to claim 2, characterized in that The hollow tapered tube is in the shape of a hollow tube, one end of which is a hollow tapered cone, the hollow tapered tube is connected to the intermediate mounting tube via a thread, the intermediate mounting tube is connected to the terminal mounting tube via a thread, and a plurality of intermediate mounting tubes are connected to each other via threads; The thread connection fixing sleeve is a hollow straight-through tubular structure, and both ends of the thread connection fixing sleeve are provided with a third external thread, and a spline groove is provided in the middle; the end mounting tube and the mating end of the thread connection fixing sleeve are provided with a first square groove for installing the limiting plate of the locking washer, and the multiple fixing plates of the outer diameter of the locking washer are bent into the spline groove after positioning.

4. The fiber Bragg grating monitoring device for uneven settlement of road subgrade according to claim 3, characterized in that, The three-way connecting seat is a hollow right-angle three-way tubular structure; the middle interface of the three-way connecting seat is provided with a third internal thread, and the engaging end of the three-way connection with the threaded connection fixing sleeve is provided with a second square groove for installing the limiting plate of the locking washer; the other end of the three-way connecting seat is provided with a second threaded through hole, and the second threaded through hole is engaged with the second threaded hole provided in the sealing cover, the sealing cover is a barrel-shaped structure, and the barrel bottom of the sealing cover is a polygonal structure.

5. The fiber Bragg grating monitoring device for uneven settlement of road subgrade according to claim 4, characterized in that, The bottom of the tilt protection cover is a hollow tube, the end of the hollow tube is provided with a fourth external thread, and the fourth external thread is engaged with the third internal thread of the middle interface of the three-way connector; A hollow barrel-shaped cover is provided at the upper end of the hollow tube, the hollow barrel-shaped cover is connected with the hollow tube space, the hollow barrel-shaped cover has no upper cover, and a plurality of inclination mounting plates are provided along the axial section position of the side surface thereof, the plurality of inclination mounting plates are used to fix the inclination mounting assembly, the inclination mounting assembly is used to fix the fiber grating inclination sensor, and can adjust the front, rear, left and right inclination angles of the fiber grating inclination sensor; a first threaded hole is provided at the top of the hollow barrel-shaped cover, the first threaded hole is used to fix the inclination protection cover; the upper part of the inclination protection cover is a circular plate, and the lower part thereof is an open circular fan plate, the circular plate is provided with a first threaded through hole, the first threaded through hole is engaged with the first threaded hole to seal the inclination protection cover and the inclination protection cover.

6. A fiber Bragg grating monitoring method for uneven settlement of road subgrade, which is realized by a fiber Bragg grating monitoring device for uneven settlement of road subgrade as described in any one of claims 1 to 5, characterized in that, The fiber grating monitoring method comprises the following steps: Step S1, during the roadbed construction or maintenance process, drill holes at key locations of the roadbed, assemble the hollow tapered tube, multiple intermediate mounting tubes, end mounting tubes, three-way connectors and sealing covers of the embedded protective housing, and assemble the hollow mounting seats, transition mounting seats, end mounting seats, locking square pins and fiber guide tubes of the strain mounting assembly; Step S2, installing fiber grating strain sensors, strain installation components, fiber grating temperature sensors and serial lines in the hollow cone tube, multiple intermediate installation tubes and terminal installation tubes, installing multiple fiber grating inclination sensors, inclination installation components and serial lines in the inclination protection cover and the inclination protection cover; the serial lines are electrically connected to the fiber grating strain sensors, fiber grating temperature sensors and fiber grating inclination sensors, and the assembled functional accessories are inserted into the key parts of the roadbed, and grouting treatment is performed after insertion; Step S3, the end of the series-connected line is a quick plug, which is electrically connected to the fiber Bragg grating demodulation system, and the fiber Bragg grating demodulation system is also electrically connected to the power supply unit; the fiber Bragg grating strain sensor is used to sense the subgrade settlement change in real time; while the series-connected fiber Bragg grating temperature sensor serves as temperature compensation, it can also monitor the temperature change at the embedding location; the fiber Bragg grating inclination sensor monitors the change in the inclination angle of the location where it is located, and is used to check whether the installation angle and position of the device are correct, and whether there is abnormal inclination or damage during operation; the series-connected line transmits the signal to the fiber Bragg grating demodulation system, and this fiber Bragg grating demodulation system collects, processes and extracts the information of the settlement amount, draws the subgrade settlement curve, analyzes the settlement trend, and this fiber Bragg grating demodulation system monitors the data according to the preset data quality standards and rules. Once data anomalies or exceeding the preset range are found, an alarm will be issued immediately. This fiber Bragg grating demodulation system provides a scientific basis for the safe operation and maintenance of the road; it can also send the data to the remote monitoring center and the mobile phone APP for timely accident warning.

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