CN109520471B - Optical fiber single-hole layered settlement monitoring device and monitoring method thereof - Google Patents
Optical fiber single-hole layered settlement monitoring device and monitoring method thereof Download PDFInfo
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- CN109520471B CN109520471B CN201811516638.5A CN201811516638A CN109520471B CN 109520471 B CN109520471 B CN 109520471B CN 201811516638 A CN201811516638 A CN 201811516638A CN 109520471 B CN109520471 B CN 109520471B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object
Abstract
The invention provides an optical fiber single-hole layered settlement monitoring device, which belongs to the field of geological disaster monitoring and comprises a plurality of cylinders which are connected end to end and are respectively arranged in different depth formations, a plurality of fiber bragg grating sensor arrays respectively arranged on the inner walls of the cylinders, demodulation equipment and a data processing module which are connected with the fiber bragg grating sensor arrays, and a filling medium; the fiber grating sensor array comprises a plurality of fiber grating sensors which are respectively arranged in the cylinder, are connected in series through one fiber and are distributed along the axial direction of the cylinder. The optical fiber single-hole layered settlement monitoring device provided by the invention has the advantages of simple structure, convenience in installation and low monitoring cost. The invention also provides a fiber single-hole layered settlement monitoring method which comprises the steps of drilling an implantation hole, implanting a cylinder into the implantation hole, enabling the cylinder to correspond to each layer one by one, enabling the cylinder to be coupled with a stratum, obtaining a strain signal and processing the strain signal. The optical fiber single-hole layered settlement monitoring method provided by the invention can realize distributed monitoring of settlement of different layers of single holes.
Description
Technical Field
The invention belongs to the technical field of geological disaster monitoring, and particularly relates to an optical fiber single-hole layered settlement monitoring device and an optical fiber single-hole layered settlement monitoring method based on the monitoring device.
Background
The development of social economy brings hot tide for the investment and construction of national infrastructure, and meanwhile, the safety problems of geotechnical engineering, mining and the like also draw great attention. The occurrence of engineering accidents such as stratum subsidence, subsidence and collapse of geotechnical engineering structures and the like caused by mineral exploitation is often accompanied by serious casualties and huge economic losses, and extremely bad social influence is caused. In addition, as a plurality of high-speed railway lines are opened successively, the trend of the traffic infrastructure projects such as high-speed railways and the like towards complex and severe geological environments such as wetlands and the like is obvious, and a small amount of deformation (such as sedimentation) of the ground surface can cause great disturbance to the trains running at high speed.
The surface subsidence is macroscopic manifestation of accumulation of subsidence deformation of deep different strata, and the subsidence deformation of the stratum at different layers threatens the safety of crossing the stratum structure and brings unsafe factors to the ground engineering structure. The existing layered settlement monitoring often adopts a multi-hole monitoring method, and each hole site corresponds to different depths; the porous monitoring causes large construction workload, scattered instruments and equipment and increases monitoring cost.
Disclosure of Invention
The invention aims to provide an optical fiber single-hole layered settlement monitoring device, which aims to solve the problems of complex multi-hole monitoring construction, scattered equipment and high cost in the prior art.
In order to achieve the above purpose, the invention adopts the following technical scheme: an optical fiber single-hole layered settlement monitoring device is provided, implanted into a formation through an implantation hole, comprising: the device comprises a plurality of cylinders which are connected end to end and are respectively arranged in different depth formations, a plurality of fiber bragg grating sensor arrays which are respectively arranged on the inner walls of the cylinders, demodulation equipment and a data processing module which are connected with the fiber bragg grating sensor arrays, and a filling medium for filling gaps between the cylinders and the implantation holes;
the fiber bragg grating sensor array comprises a plurality of fiber bragg grating sensors which are respectively arranged in a plurality of cylinders, are connected in series through an optical fiber and are distributed along the axial direction of the cylinders, and the optical fiber is connected with the demodulation equipment and the data processing module.
Further, the cylinder is a stainless steel member, and the wall thickness of the cylinder is 0.5-2mm.
Further, the fiber bragg grating sensor arrays are four, wherein three fiber bragg grating sensor arrays are distributed on the inner wall of the cylinder at intervals of 90 degrees, and the other fiber bragg grating sensor array is arranged in a suspended mode on the inner wall of the cylinder; the bending correction is realized through the arrangement of fiber grating sensor arrays at intervals of 180 degrees; meanwhile, judging the direction of extrusion bending through an optical fiber grating sensor array with an interval of 90 degrees; temperature sensing and compensation are achieved through a suspended fiber grating sensor array.
Further, the filling medium is cement mortar.
Further, the cylinder is provided with a first connecting area, a consolidation area, a sensing area and a second connecting area, wherein the consolidation area is used for filling the filling medium into the cylinder and enabling the cylinder to be in coordinated deformation with surrounding soil, the sensing area is used for accommodating the fiber bragg grating sensor, the second connecting area is fixedly connected with the first connecting area of the adjacent cylinder through a connector, and the fiber bragg grating in the sensing area is packaged in a long gauge length mode and is used for sensing average strain of the cylinder in a corresponding area.
Further, the consolidation zone comprises a first sealing layer, a second sealing layer, a slurry inlet hole and a fiber channel, wherein the first sealing layer is in sealing connection with the inner wall of the cylinder and is positioned below the first connection zone, the second sealing layer is in sealing connection with the inner wall of the cylinder and is positioned above the sensing zone, the slurry inlet hole is formed in the side wall of the cylinder and is positioned between the first sealing layer and the second sealing layer, and the fiber channel is communicated with the first connection zone and the sensing zone.
Further, the connector comprises a sleeve and an internal thread structure arranged in the sleeve, the first connecting area comprises a first external thread arranged on the outer wall of the cylinder and matched with the internal thread structure, and the second connecting area comprises a second external thread arranged on the outer wall of the cylinder and matched with the internal thread structure; the first external thread and the second external thread are opposite in screwing direction, the internal thread structure comprises a first internal thread which is arranged at one end of the sleeve and matched with the first external thread, and a second internal thread which is arranged at the other end of the sleeve and matched with the second external thread, and the screwing direction of the first internal thread and the screwing direction of the second internal thread are opposite.
Further, the wall thickness of the sleeve is larger than 5mm, and the part of the sleeve protruding out of the cylinder in the radial direction is an end cap.
The optical fiber single-hole layered settlement monitoring device provided by the invention has the beneficial effects that: compared with the prior art, the optical fiber single-hole layered settlement monitoring device provided by the invention has the advantages that the optical fiber grating sensor can accurately sense tiny strain, based on the technical advantages of single-fiber multi-sensor multiplexing of the optical fiber grating sensor, the cylinders are matched with the optical fiber grating sensor to form the sensing element, each cylinder corresponds to one horizon of a stratum, the sensing element can accurately track the strain change of each horizon, and the settlement of the stratum is monitored through accumulation of the strain of each horizon. The optical fiber single-hole layered settlement monitoring device provided by the invention can realize synchronous monitoring of settlement deformation of different layers by punching and implanting the cylinder with the fiber bragg grating sensor array, has the advantages of simple structure, convenience in installation and low monitoring cost, and solves the problems of complex construction, dispersion and high monitoring cost of multi-hole monitoring.
The invention also provides an optical fiber single-hole layered settlement monitoring method, which is realized based on the optical fiber single-hole layered settlement monitoring device and comprises the following steps:
drilling an implantation hole, and implanting the cylinder provided with the fiber bragg grating sensor array into the implantation hole, so that the cylinder corresponds to each layer in the stratum one by one;
coupling between the cylinder and the formation with the packing medium;
and tracking the strain change of each horizon by using a sensitive element formed by compounding the fiber grating sensor array and the cylinder, and acquiring stratum settlement information through accumulation of the strain change in the cylinder.
Further, the tracking the strain change of each horizon by using the sensing element formed by compounding the fiber bragg grating sensor array and the cylinder, and the acquiring the stratum settlement information by accumulating the strain change in the cylinder comprises the following steps:
transmitting friction force caused by stratum settlement to the fiber bragg grating sensor array through the filling medium and the cylinder, so that the fiber bragg grating sensor obtains a strain signal;
processing the strain signal through the demodulation equipment and the data processing module to obtain different horizon settlement information;
the settlement information comprises a macroscopic settlement amount, wherein the macroscopic settlement amount of a specified horizon is equal to the sum of settlement deformations of all horizons below the specified horizon.
The optical fiber single-hole layered settlement monitoring method provided by the invention has the beneficial effects that: compared with the prior art, the optical fiber single-hole layered settlement monitoring method has the advantages that the sensing element is drilled and implanted in the stratum, the filling medium capable of ensuring that the strain is accurately transmitted to the cylinder is filled in the gap between the cylinder and the implanted hole, so that accurate strain signals are obtained, the accurate settlement strain information can be obtained through processing the strain signals by demodulation equipment and a data processing module, the testing method is simple, the construction difficulty is low, and the synchronous monitoring of settlement deformation of different layers is realized by utilizing a single measuring hole based on the technical advantage of single-fiber multi-sensor multiplexing of the optical fiber grating sensor.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a distribution structure of an optical fiber single-hole layered settlement monitoring device according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of the internal structure of the cylinder of FIG. 1;
FIG. 3 is a cross-sectional view of the top structure of the cylinder of FIG. 1;
FIG. 4 is a cross-sectional view of the internal structure of the connector of FIG. 1;
FIG. 5 is a schematic diagram of the operation of the optical fiber single-hole layered settlement monitoring device according to the embodiment of the invention;
fig. 6 is a flowchart of an optical fiber single-hole layered settlement monitoring method according to an embodiment of the present invention.
Wherein, each reference sign in the figure:
1-implanting holes; 2-a cylinder; 201-a first connection region; 202-consolidation zone; 2021-a first sealing layer; 2022-a second sealing layer; 2023-pulp inlet; 2024-fibre channel; 203-a sensing region; 204-a second connection region; 3-optical fiber; 4-fiber grating sensor; 5-monitoring management center; 6-an optical switch; 7-a demodulator; 8-an industrial personal computer; 9-a communication interface; 10-a wireless communication module; 11-a connector; 1101-section; 1102-first internal threads; 1103-second internal thread
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Referring to fig. 1 to 5, an optical fiber single-hole layered settlement monitoring device provided by the invention will now be described. The optical fiber single-hole layered settlement monitoring device is implanted into a stratum through an implantation hole 1 and comprises a plurality of cylinders 2 which are connected end to end and are respectively arranged in the stratum with different depths, a plurality of fiber bragg grating sensor arrays respectively arranged on the inner walls of the cylinders 2, demodulation equipment and a data processing module which are connected with the fiber bragg grating sensor arrays, and a filling medium for filling gaps between the cylinders 2 and the implantation hole 1;
the fiber grating sensor array comprises a plurality of fiber grating sensors 4 which are respectively arranged in a plurality of cylinders 2 and are connected in series through an optical fiber 3 and are distributed along the axial direction of the cylinders 2, and the optical fiber 3 is connected with demodulation equipment and a data processing module.
An optical fiber 3 is arranged in an optical fiber grating sensor array, so that the number of outgoing lines of monitoring points is simplified, and data acquisition and on-site management are facilitated.
It should be noted that the cylinder 2 should be a thin walled cylinder to enable an efficient transfer of strain to the fiber grating sensor 4.
As an emerging monitoring technical means, the fiber optic grating sensing technology has become a hotspot for geotechnical engineering researches, and is a relatively mature one, and has the advantages of high precision, good stability, long sensing distance and the like.
The fiber grating is a structure which is prepared by taking a high germanium-doped photosensitive fiber as a base material and adopting a phase mask method and periodically changes along the refractive index of a fiber core. When broadband light enters the fiber bragg grating, the grating selectively reflects the incident light, and the central wavelength of the reflected light is the Bragg wavelength. The Bragg wavelength may be expressed asλ B =2n eff ΛWherein, the method comprises the steps of, wherein,λ B bragg wavelength for the grating; n is n eff Is the effective refractive index of the grating;Λis the grating pitch.
The grating pitch and the effective refractive index of the grating are influenced by the external environment temperature and the strain, and the temperature or the strain at the grating can be determined by accurately measuring the Bragg wavelength of the light reflected by the grating; the external micro-displacement change can also be detected by effectively packaging the fiber bragg grating to manufacture a displacement sensor.
The cylinder 2 is matched with the fiber grating sensor 4 to form a sensing element, and the friction force caused by stratum rock and soil settlement transmitted by the cylinder 2 and surrounding filling media is sensed. Because the cylinder 2 is coupled with the stratum through the filling medium, stress generated by settlement deformation of surrounding stratum rock soil can be accurately transmitted to the cylinder 2 through the filling medium and then transmitted to the fiber bragg grating sensor 4 through the cylinder 2, and the fiber bragg grating sensor 4 can accurately sense strain.
Compared with the prior art, the optical fiber single-hole layered settlement monitoring device provided by the invention has the advantages that the optical fiber grating sensor 4 can accurately sense tiny strain, the cylinder 2 is matched with the optical fiber grating sensor 4 to form a sensing element based on the technical advantage of single-fiber multi-sensor multiplexing of the optical fiber grating sensor 4, each cylinder 2 corresponds to one horizon of a stratum, the sensing element can accurately track the strain change of each horizon, and the settlement of the stratum is monitored through the accumulation of the strain of each horizon. The optical fiber single-hole layered settlement monitoring device provided by the invention has a simple structure, can realize synchronous monitoring of settlement deformation of different layers by punching and implanting the cylinder 2 with the fiber bragg grating sensor array, has the advantages of simple structure, convenience in installation and low monitoring cost, and solves the problems of complex multi-hole monitoring construction and high monitoring cost.
Furthermore, the system is based on the fiber grating sensing principle and combines with an advanced transmission means to realize quasi-distributed real-time monitoring of settlement deformation of different layers of the stratum, and ensure the safe service of surrounding engineering structures.
Further, referring to fig. 5, as a specific embodiment of the optical fiber single-hole layered settlement monitoring device provided by the invention, the demodulation device and the data processing module include a data acquisition station and a monitoring management center 5 for performing information interaction with the data acquisition station. The data acquisition station is connected with the optical fiber 3 of the on-site monitoring node through an optical cable and is used for acquiring and processing real-time data; the data acquisition station comprises an optical switch 6 for switching different channels; a demodulator 7 for demodulating the grating wavelength variation and restoring the strain value; the industrial personal computer 8 is used for temporarily storing and processing the demodulation data; a communication interface 9 for completing communication with a wireless communication module 10; the wireless communication module 10 is connected with the data acquisition station through a wireless transmission mode, and is responsible for dynamic analysis of the whole line, and timely finding out dangerous situations and issuing early warning reports. The demodulation equipment and the data processing module can realize unattended operation and have two modes of timing monitoring and real-time remote operation monitoring.
Further, as a specific embodiment of the optical fiber single-hole layered settlement monitoring device provided by the invention, the cylinder 2 is a stainless steel member, and the wall thickness of the cylinder 2 is 0.5-2mm.
Specifically, as a specific implementation mode of the optical fiber single-hole layered settlement monitoring device provided by the invention, the length and the like of the cylinder 2 can be set according to the stratum horizon thickness and other measurement requirements, for example, a thin-wall cylinder with the length of 1m, the outer diameter of 40mm and the wall thickness of 1mm is set.
Further, referring to fig. 2, as a specific implementation manner of the optical fiber single-hole layered settlement monitoring device provided by the invention, four fiber bragg grating sensor arrays are provided, wherein three fiber bragg grating sensor arrays are distributed on the inner wall of the cylinder 2 at intervals of 90 degrees, and the other fiber bragg grating sensor array is suspended on the inner wall of the cylinder 2; the bending correction is realized through the arrangement of fiber grating sensor arrays at intervals of 180 degrees; meanwhile, judging the direction of extrusion bending through an optical fiber grating sensor array with an interval of 90 degrees; temperature sensing and compensation are achieved through a suspended fiber grating sensor array.
Further, referring to fig. 3, as a specific embodiment of the optical fiber single-hole layered settlement monitoring device provided by the invention, an optical fiber grating sensor array includes at least one optical fiber grating sensor 4. To simplify the structure, the fiber grating sensors 4 in each fiber grating sensor array are in one-to-one correspondence with the cylinders 2. I.e. one fiber grating sensor array, only one fiber grating sensor 4 is arranged in one cylinder 2.
Four fiber grating sensor arrays are uniformly distributed around the central axis of the cylinder 2, wherein the fiber grating sensors 4 in three fiber grating sensor arrays are fixedly connected with the inner wall of the cylinder 2 respectively and used for sensing strain, and the fiber grating sensors 4 in the other fiber grating sensor arrays are used for sensing temperature. The bending correction can be more effectively realized through the arrangement of three fiber grating sensor arrays (three fiber grating sensors 4 positioned at the upper, lower and right sides in fig. 3) with 90 degrees of intervals, and the direction of extrusion bending can be judged; meanwhile, the influence of uneven deformation is further reduced by averaging the two fiber grating sensor arrays which are 180 degrees apart. In order to eliminate the influence of temperature, the fiber bragg grating sensors 4 (three fiber bragg grating sensors 4 positioned at the left side in fig. 3) in the other fiber bragg grating sensor array are in lap contact with the inner wall of the cylinder 2 but are not fixed, and the fiber bragg grating sensors are used as temperature sensors, so that the temperature field information of the horizon rock soil can be provided.
The specific calculation process comprises the following steps:
taking the drawing as an example, three fiber grating sensors 4 located above, right and below in fig. 3 are a first sensor, a second sensor and a third sensor, respectively, and three fiber grating sensors 4 located at left in fig. 3 are fourth sensors. And taking an average value by using the first sensor and the third sensor to realize bending correction, wherein the calculation process is as follows: first calculate the strain of the nth layer cylinder 2Then calculate the deformation of the nth layer cylinder 2 +.>Finally obtaining macroscopic settlement of the stratum of the nth layer>. Judging extrusion bending direction by using pulling and pressing combination of the first sensor, the second sensor and the third sensor and compensating partial non-uniform deformation, wherein the calculation formula of bending angle is->. Wherein, the liquid crystal display device comprises a liquid crystal display device,ε 1 for the strain sensed by the first sensor,ε 2 for the strain sensed by the second sensor,ε 3 for the strain sensed by the third sensor,L n is the effective sensing length of the nth level cylinder.
Further, as a specific implementation mode of the optical fiber single-hole layered settlement monitoring device provided by the invention, the filling medium is cement mortar. The cement mortar should have a desired strength and adhesion after hardening, and be suitable for tightly coupling the cylinder 2 and the implantation hole 1.
Further, referring to fig. 1, 2 and 4, as a specific embodiment of the optical fiber single-hole layered settlement monitoring device provided by the present invention, a first connection area 201, a consolidation area 202 located in the cylinder 2 and used for filling a filling medium and for coordinately deforming the cylinder 2 with surrounding soil, a sensing area 203 used for accommodating the fiber bragg grating sensor 4, and a second connection area 204 are sequentially distributed from top to bottom in the cylinder 2, and the second connection area 204 of the cylinder 2 is fixedly connected with the first connection area 201 of an adjacent cylinder 2 through a connector 11.
The consolidation area 202 is used for infiltration of the filling medium, ensures integration with the filling medium outside the cylinder 2, and maintains synchronous deformation.
Further, referring to fig. 2, as an embodiment of the optical fiber single-hole layered settlement monitoring device provided by the present invention, the consolidation zone 202 includes a first sealing layer 2021 sealingly connected to the inner wall of the cylinder 2 and located below the first connection zone 201, a second sealing layer 2022 sealingly connected to the inner wall of the cylinder 2 and located above the sensing zone 203, a slurry inlet 2023 provided on the sidewall of the cylinder 2 and located between the first sealing layer 2021 and the second sealing layer 2022, and an optical fiber channel 2024 communicating the first connection zone 201 and the sensing zone 203. The cylinder 2 is provided with a slurry inlet 2023 which is convenient for the filling medium to flow in, and a consolidation area 202 is formed in a certain range in the cylinder 2, so that good stress transmission effect inside and outside the cylinder is ensured; at the same time, the consolidation zone 202 segments the cylinder 2, and each sensing element is responsible for monitoring the settlement of the exclusive area, thereby forming a quasi-distributed monitoring system.
Specifically, as a specific embodiment of the optical fiber single-hole layered settlement monitoring device provided by the invention, an optical fiber channel 2024 for allowing an optical fiber 3 to penetrate is positioned between the first sealing layer 2021 and the second sealing layer 2022 and is respectively connected with the first sealing layer 2021 and the second sealing layer 2022 in a sealing manner.
Further, referring to fig. 1, 2 and 4, as an embodiment of the optical fiber single-hole layered settlement monitoring device provided by the present invention, the connector 11 includes a sleeve 1101 and an internal thread structure disposed in the sleeve 1101, the first connection region 201 includes a first external thread disposed on an outer wall of the cylinder 2 and engaged with the internal thread structure, and the second connection region 204 includes a second external thread disposed on an outer wall of the cylinder 2 and engaged with the internal thread structure. The sleeve 1101 has an outer diameter (e.g., 50 mm) greater than the outer diameter of barrel 2 and the portion protruding relative to barrel 2 may function as a conventional strain gauge end cap while increasing the rigidity of the connection of barrel 2.
Further, referring to fig. 2 and 4, as an embodiment of the optical fiber single-hole layered settlement monitoring device provided by the present invention, the internal thread structure includes a first internal thread 1102 provided at one end of the sleeve 1101 and engaged with the first external thread, and a second internal thread 1103 provided at the other end of the sleeve 1101 and engaged with the second external thread, wherein the first external thread and the second external thread are in opposite directions, and the first internal thread 1102 and the second internal thread 1103 are in opposite directions. The screw threads at the two ends of the cylinder 2 are reversed in rotation direction, so that the rotation can not occur during installation, and the knotting of the optical fiber 3 in the cylinder 2 is avoided.
Further, referring to fig. 1, as an embodiment of the optical fiber single-hole layered settlement monitoring device provided by the invention, a wall thickness of a sleeve 1101 is greater than 5mm, and a portion of the sleeve 1101 protruding radially from a cylinder 2 is an end cap. The end cap can increase the rigidity of the device at the connection location and also can function as a conventional strain gauge end cap.
Referring to fig. 6, the invention further provides an optical fiber single-hole layered settlement monitoring method, which is implemented based on the optical fiber single-hole layered settlement monitoring device, and comprises the following steps:
drilling an implantation hole 1, implanting a cylinder 2 provided with a fiber grating sensor array into the implantation hole 1, and enabling the cylinder 2 to correspond to each layer in the stratum one by one;
filling the gap between the cylinder 2 and the implantation hole 1 with a filling medium, and coupling the cylinder 2 and the stratum with the filling medium;
the strain change of each horizon is tracked by utilizing a sensitive element formed by compounding the fiber grating sensor array and the cylinder 2, and stratum settlement information is obtained through accumulation of the strain change in the cylinder.
According to the optical fiber single-hole layered settlement monitoring method provided by the invention, the sensing element is drilled and implanted in the stratum, the filling medium capable of ensuring that the strain is accurately transmitted to the cylinder is filled in the gap between the cylinder 2 and the implanted hole 1 so as to obtain an accurate strain signal, and the strain signal is processed by demodulation equipment and a data processing module so as to obtain accurate settlement strain information.
Further, tracking strain change of each horizon by using a sensing element formed by compounding the fiber grating sensor array and the cylinder, and acquiring stratum settlement information by accumulating the strain change in the cylinder comprises the following steps:
transmitting friction force caused by stratum settlement to the fiber bragg grating sensor array through the filling medium and the cylinder 2, so that the fiber bragg grating sensor 4 obtains a strain signal;
processing the strain signals through demodulation equipment and a data processing module to obtain different horizon settlement information;
the settlement information comprises macroscopic settlement amount, wherein the macroscopic settlement amount of the designated horizon is equal to the sum of settlement deformations of all horizons below the designated horizon
If the formation is divided into N layers, the sensor tracks the strain change of each formation during the monitoring process, and the monitoring of the formation settlement is achieved by accumulation in the sensing area 203 of the cylinder 2. The macroscopic settlement amount of the stratum n is equal to the sum of settlement deformation of the stratum n below the macroscopic settlement amount.
Further, before drilling the implantation hole 1, it further comprises:
and measuring the position of the lofting drilling hole, so that the drilling hole can accurately reflect the actual deformation state of the surrounding rock and soil.
Specifically, the drill implant hole 1 includes:
the spiral drilling machine drills holes to bedrock, the aperture is larger than the outer diameter of the cylinder 2 (for example, 90 mm), the protection of the hole wall is paid attention to in the drilling process, and the phenomenon that the hole wall is immersed for a long time to collapse is avoided;
and after drilling, cleaning the holes.
Specifically, implanting the cylinder 2 provided with the fiber grating sensor array into the implantation hole 1 includes:
after the fiber bragg grating sensor 4 is packaged well, the fiber bragg grating sensor is directly installed in the cylinder 2 on site;
by adopting a process of assembling and lowering simultaneously, the cylinders 2 are gradually lowered through two symmetrical side lugs on the cylinders 2, and the two adjacent cylinders 2 are assembled in the lowering process.
The descending adopts a mode of dragging a steel wire rope, and ensures that the descending process is smoothly and stably carried out. The deformation such as torsion, bending and the like can not be generated as much as possible when the device is placed too high.
Specifically, filling the space between the cylinder 2 and the implantation hole 1 with the filling medium includes:
and (3) adopting a pressure grouting and bottom-up mode, and grouting while lifting the grouting pipe until the grouting pipe is full.
Specifically, the filling medium comprises the following components: sand: water = 1:1:0.65, the cement is ordinary silicate cement with the standard mark of 32.5R, and the sand is clean river sand with the particle size of 1.25-2.5 mm.
Specifically, processing the strain signal by the demodulation apparatus and the data processing module includes:
acquiring sensing signals of the fiber bragg grating sensors 4 at different nodes through the optical switch 6;
demodulating the grating wavelength change and restoring the strain value by a demodulator 7;
temporary storage and processing of the demodulated data by the industrial personal computer 8;
the communication is completed between the monitoring management center 5 and the wireless communication module 10 through the communication interface 9, and the wireless communication module 10 is in wireless transmission connection with the monitoring management center 5;
the data are supervised by the monitoring management center 5.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (7)
1. Optical fiber single-hole layered settlement monitoring device is implanted into the stratum through an implantation hole, and is characterized in that: comprises a plurality of cylinders which are connected end to end and are respectively arranged in different depth formations, a plurality of fiber bragg grating sensor arrays respectively arranged on the inner walls of the cylinders, and optical fibers
A demodulation device and a data processing module connected with the grating sensor array, and a filling medium for filling a gap between the cylinder and the implantation hole;
the fiber bragg grating sensor array comprises a plurality of fiber bragg grating sensors which are respectively arranged in a plurality of cylinders, are connected in series through an optical fiber and are distributed along the axial direction of the cylinders, and the optical fiber is connected with the demodulation equipment and the data processing module;
the filling medium is cement mortar; the cylinder is provided with a first connecting area, a consolidation area, a sensing area and a second connecting area, wherein the consolidation area is used for filling the filling medium and enabling the cylinder to be in coordinated deformation with surrounding soil, the sensing area is used for accommodating the fiber bragg grating sensor, the second connecting area of the cylinder is fixedly connected with the first connecting area of the adjacent cylinder through a connector, and the fiber bragg grating in the sensing area is packaged in a long gauge length mode and is used for sensing average strain of the cylinder in a corresponding area;
the consolidation zone comprises a first sealing layer, a second sealing layer, a slurry inlet hole and a fiber channel, wherein the first sealing layer is in sealing connection with the inner wall of the cylinder and is positioned below the first connection zone, the second sealing layer is in sealing connection with the inner wall of the cylinder and is positioned above the sensing zone, the slurry inlet hole is formed in the side wall of the cylinder and is positioned between the first sealing layer and the second sealing layer, and the fiber channel is communicated with the first connection zone and the sensing zone; the fiber channel for enabling the optical fiber to penetrate is located between the first sealing layer and the second sealing layer and is respectively connected with the first sealing layer and the second sealing layer in a sealing mode.
2. The optical fiber single-hole layered settlement monitoring device as claimed in claim 1, wherein: the cylinder is a stainless steel member, and the wall thickness of the cylinder is 0.5-2mm.
3. The optical fiber single-hole layered settlement monitoring device as claimed in claim 1, wherein: the fiber bragg grating sensor arrays are four, three fiber bragg grating sensor arrays are distributed on the inner wall of the cylinder at intervals of 90 degrees, and the other fiber bragg grating sensor array is arranged in a suspended mode on the inner wall of the cylinder; the bending correction is realized through the arrangement of fiber grating sensor arrays at intervals of 180 degrees; meanwhile, judging the direction of extrusion bending through an optical fiber grating sensor array with an interval of 90 degrees; temperature sensing and compensation are achieved through a suspended fiber grating sensor array.
4. The optical fiber single-hole layered settlement monitoring device as claimed in claim 1, wherein: the connector comprises a sleeve and an internal thread structure arranged in the sleeve, the first connecting area comprises a first external thread arranged on the outer wall of the cylinder and matched with the internal thread structure, and the second connecting area comprises a second external thread arranged on the outer wall of the cylinder and matched with the internal thread structure; the first external thread and the second external thread are opposite in screwing direction, the internal thread structure comprises a first internal thread which is arranged at one end of the sleeve and matched with the first external thread, and a second internal thread which is arranged at the other end of the sleeve and matched with the second external thread, and the screwing direction of the first internal thread and the screwing direction of the second internal thread are opposite.
5. The optical fiber single-hole layered settlement monitoring device as set forth in claim 4, wherein: the wall thickness of the sleeve is larger than 5mm, and the part of the sleeve protruding out of the cylinder in the radial direction is an end cap.
6. The optical fiber single-hole layered settlement monitoring method is characterized by being realized based on the optical fiber single-hole layered settlement monitoring device as claimed in any one of claims 1 to 5, and comprises the following steps:
drilling an implantation hole, and implanting the cylinder provided with the fiber bragg grating sensor array into the implantation hole, so that the cylinder corresponds to each layer in the stratum one by one;
coupling between the cylinder and the formation with the packing medium;
and tracking the strain change of each horizon by using a sensitive element formed by compounding the fiber grating sensor array and the cylinder, and acquiring stratum settlement information through accumulation of the strain change in the cylinder.
7. The method for monitoring optical fiber single-hole layered settlement according to claim 6, which is characterized in that: tracking strain change of each horizon by using a sensitive element formed by compounding the fiber bragg grating sensor array and the cylinder, and acquiring stratum settlement information through accumulation of the strain change in the cylinder comprises the following steps:
transmitting friction force caused by stratum settlement to the fiber bragg grating sensor array through the filling medium and the cylinder, so that the fiber bragg grating sensor obtains a strain signal;
processing the strain signal through the demodulation equipment and the data processing module to obtain different horizon settlement information;
the settlement information comprises a macroscopic settlement amount, wherein the macroscopic settlement amount of a specified horizon is equal to the sum of settlement deformations of all horizons below the specified horizon.
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| CN114370852B (en) * | 2021-12-15 | 2024-03-05 | 安徽理工大学 | Accurate evaluation method and system for working face well-ground joint test ground subsidence basin |
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