Strain monitoring system and construction method thereof

Abstract

The invention provides a strain monitoring system and a construction method thereof, the strain monitoring system is used for monitoring the strain of a measured pipeline, the strain monitoring system comprises a monitoring channel, an optical fiber and a monitoring piece, the monitoring channel is arranged between the inner wall of the measured pipeline and the outer wall of the measured pipeline, part of the optical fiber is arranged in the monitoring channel, and the optical fiber extends along the monitoring channel; a filling body is also arranged in the monitoring channel, the filling body is filled between the optical fiber and the inner wall of the monitoring channel, and the filling body is suitable for transmitting the strain of the measured pipeline to the optical fiber; the monitoring member is connected with the optical fiber to monitor the strain of the optical fiber at each position along the length direction. The strain monitoring system provided by the invention has the advantage of high strain measurement precision of the measured pipeline.

Description

Technical Field

[0001] The present application belongs to the technical field of building monitoring, and more specifically, to a strain monitoring system and a construction method thereof. Background Art

[0002] During the construction and operation of shield tunnels, due to the combined effects of multiple factors such as the quality of the lining segments, the quality of the shield tail grouting, environmental changes inside and outside the tunnel, and cyclic loads, the shield tunnel segments are very prone to defects such as water leakage, structural cracks, longitudinal settlement, and overall convergence deformation.

[0003] Distributed fiber grating technology is used in the related art to monitor the strain of the pipe segment. However, the monitoring accuracy of the strain monitoring system in the related art is not high. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a strain monitoring system to solve the technical problem of low monitoring accuracy of the strain monitoring system in the related art in the prior art.

[0005] To achieve the above-mentioned purpose, the technical solution adopted in the present application is: to provide a strain monitoring system for monitoring the strain of a measured pipeline, the strain monitoring system comprising: a monitoring channel and an optical fiber, the monitoring channel being arranged between the inner wall of the measured pipeline and the outer wall of the measured pipeline, the optical fiber being arranged in the monitoring channel and extending along the monitoring channel, a filling body being also arranged in the monitoring channel, the filling body being filled between the optical fiber and the inner wall of the monitoring channel, the filling body being suitable for transmitting the strain of the measured pipeline to the optical fiber; a monitoring component, the monitoring component being connected to the optical fiber to monitor the strain of the optical fiber at various positions along its length direction.

[0006] The beneficial effects of the strain monitoring system provided by the present application are as follows: compared with the prior art, the strain monitoring system of the present application is filled with a filling body between the inner wall of the monitoring channel and the optical fiber. On the one hand, when the measured pipeline is strained, the strain of the measured pipeline can be transmitted to the optical fiber through the filling body, which improves the average strain transmission efficiency in the process of transmitting the strain from the measured pipeline to the optical fiber, so that the strain monitoring system provided by the present application can accurately monitor the strain amount, and thus the strain monitoring system 100 provided by the present application has the advantage of high monitoring accuracy; on the other hand, the filling body is filled in the monitoring channel, so that the strain of the measured pipeline can be extended in the monitoring channel. The strain of any point in the direction is transmitted to the optical fiber, so that the strain monitoring system provided by the present application can accurately locate the stress concentration position, thereby making the strain monitoring system 100 provided by the present application have the advantage of higher monitoring accuracy; thirdly, the monitoring channel is arranged between the inner wall of the measured pipeline and the outer wall of the measured pipeline. When the measured pipeline is under pressure, the strain of the inner wall of the measured pipeline and the strain of the outer wall of the measured pipeline can be transmitted to the optical fiber in the monitoring channel, so that the strain monitoring system provided by the present application can simultaneously monitor the strain of the inner wall of the measured pipeline and the strain of the outer wall of the measured pipeline, thereby making the strain monitoring system provided by the present application have the advantage of higher monitoring accuracy.

[0007] Optionally, there are multiple monitoring channels, which extend axially along the measured pipeline and are arranged at intervals along the circumference of the measured pipeline. There are multiple optical fibers, which are arranged one-to-one in the monitoring channels.

[0008] Optionally, the plurality of optical fibers include a first optical fiber and a second optical fiber, the monitoring device is suitable for monitoring the strain of the measured pipeline through the first optical fiber, and the monitoring device is suitable for monitoring the temperature of the measured pipeline through the second optical fiber to compensate for the strain of the first optical fiber.

[0009] Optionally, the strain monitoring system further comprises a pre-buried pipe, wherein the pre-buried pipe is cast between an inner wall of the measured pipeline and an outer wall of the measured pipeline, and the monitoring channel is formed in the pre-buried pipe.

[0010] Optionally, the ratio of the elastic modulus of the filling body to the elastic modulus of the measured pipeline is 0.25-0.35;

[0011] And / or, the filling body is formed by solidifying cement paste.

[0012] Optionally, the pipeline under test includes a plurality of pipe segments, and the monitoring channel penetrates the plurality of pipe segments along the axial direction of the pipeline under test.

[0013] The present application also proposes a construction method of a strain monitoring system, comprising:

[0014] A monitoring channel is provided between the inner wall of the measured pipeline and the outer wall of the measured pipeline;

[0015] Placing an optical fiber into the monitoring channel along an extension direction of the monitoring channel;

[0016] Filling material is injected into the monitoring channel, and the filling material is solidified to form a filling body filled in the monitoring channel, and the filling body is suitable for transmitting the strain of the measured pipeline to the optical fiber.

[0017] Optionally, a monitoring channel is provided between the inner wall and the outer wall of the measured pipeline, including:

[0018] Performing a loading test on the tested pipeline to determine the radial position where stress concentration occurs in the tested pipeline;

[0019] The monitoring channel is arranged at a radial position where stress concentration occurs in the measured pipeline.

[0020] Optionally, the pipeline under test includes a plurality of segments, and a loading test is performed on the pipeline under test to determine a radial position where stress concentration occurs in the pipeline under test, including:

[0021] Randomly select one or more of the segments in the tested pipeline and perform a loading test on the segments;

[0022] According to the radial position of the pipe segment when it fails under loading, the radial position where stress concentration occurs in the measured pipeline is determined.

[0023] Optionally, placing the optical fiber into the monitoring channel along the extension direction of the monitoring channel further comprises:

[0024] Connecting a plurality of brackets to the optical fiber;

[0025] Placing the optical fiber together with the plurality of brackets into the monitoring channel;

[0026] The bracket is supported against the inner wall of the monitoring channel so that the optical fiber extends along the axis of the monitoring channel;

[0027] A pre-tensioning force is applied to the optical fiber to keep the optical fiber straight in the monitoring channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 A schematic diagram of the structure of a strain monitoring system provided in an embodiment of the present application;

[0030] Figure 2 A schematic diagram of the structure of a filling body and a pre-buried pipe of a strain monitoring system provided in an embodiment of the present application;

[0031] Figure 3 A schematic diagram of the structure of a pipe segment of a strain monitoring system provided in an embodiment of the present application;

[0032] Among them, the reference numerals in the figure are:

[0033] 100. strain monitoring system; 11. optical fiber; 111. first optical fiber; 112. second optical fiber; 12. filling body; 13. monitoring element; 14. embedded pipe; 15. monitoring channel;

[0034] 200. Pipeline under test; 21. Pipe segment. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or 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 indirectly connected to the other element.

[0037] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] Please also read Figure 1 and Figure 2 The strain monitoring system 100 provided in the embodiment of the present application is now described. The strain monitoring system 100 is used to monitor the strain of the pipeline 200 under test. The strain monitoring system 100 includes a monitoring channel 15 , an optical fiber 11 and a monitoring component 13 .

[0040] The monitoring channel 15 is arranged between the inner wall of the measured pipeline 200 and the outer wall of the measured pipeline 200, part of the optical fiber 11 is arranged in the monitoring channel 15, and the optical fiber 11 extends along the monitoring channel 15. A filling body 12 is also provided in the monitoring channel 15, and the filling body 12 is filled between the optical fiber 11 and the inner wall of the monitoring channel 15. The filling body 12 is suitable for transferring the strain of the measured pipeline 200 to the optical fiber 11.

[0041] Specifically, Figure 1 As shown, the pipeline 200 under test is along Figure 1 The axial direction of the measured pipeline 200 is Figure 1 In the x direction shown in the figure, the monitoring channel 15 is arranged in the pipe wall of the measured pipe 200, and the monitoring channel 15 extends along the axial direction of the measured pipe 200, the optical fiber 11 is arranged in the monitoring channel 15, and the optical fiber 11 extends along the monitoring channel 15 so that the optical fiber 11 extends along the axial direction of the measured pipe 200. When the measured pipe 200 is strained due to pressure or temperature changes, the strain of the measured pipe 200 can be transmitted to the optical fiber 11, thereby changing the refractive index of the optical fiber 11 to the pulse of the optical fiber 11.

[0042] The filling body 12 is filled in the monitoring channel 15 and coated on the outside of the optical fiber 11. On the one hand, the filling body 12 can support the part of the optical fiber 11 in the monitoring channel 15, avoiding the optical fiber 11 from directly contacting the inner wall of the monitoring channel 15 and thus affecting the monitoring accuracy of the strain monitoring system 100 provided in the present application. On the other hand, the filling body 12 can effectively transfer the strain of the inner wall of the monitoring channel 15 to the optical fiber 11, thereby improving the transmission efficiency of the strain from the measured pipeline 200 to the optical fiber 11.

[0043] The monitoring element 13 is connected to the optical fiber 11 to monitor the strain at various positions of the optical fiber 11 along its length.

[0044] Specifically, the monitoring device 13 is composed of a light source, a pulse modulator, a circulator, a fiber optic sensor, and a data acquisition and processing system. Part of the optical fiber 11 extends into the monitoring channel 15, and part of the optical fiber 11 extends to the outside of the monitoring channel 15. Part of the optical fiber 11 outside the monitoring channel 15 is connected to the monitoring device 13 so that a detection pulse beam can be introduced into the optical fiber 11 through the monitoring device 13.

[0045] The detection pulse propagates in the optical fiber 11, and generates Brillouin scattered light along the extension direction of the optical fiber 11. The monitoring element 13 detects the power and frequency shift of the Brillouin scattered light, and obtains the distance in the extension direction of the optical fiber 11 according to the propagation speed of the detection pulse in the optical fiber 11 and the change of the Brillouin scattered light in the time domain.

[0046] The monitoring element 13 processes the power and frequency shift of the obtained Brillouin backscattered light to obtain temperature information and strain information of each part of the optical fiber 11. The relationship between the position L of the Brillouin backscattered light frequency shift change in the optical fiber 11 and the pulse propagation time t is:

[0047]

[0048] Where c is the speed of light in a vacuum.

[0049] It can be understood that there is a good linear relationship between the frequency shift of the Brillouin backscattered light and the strain and temperature change of the optical fiber 11. Therefore, when the measured pipeline 200 undergoes strain changes, the strain of the measured pipeline 200 is transmitted to the optical fiber 11 laid inside the monitoring channel 15, so that the optical fiber 11 and the measured pipeline 200 are deformed synchronously to generate tension and compression, thereby changing the power and frequency shift of the Brillouin backscattered light obtained by the monitoring element 13.

[0050] Thus, the monitoring element 13 measures the frequency shift of the Brillouin backscattered light, and based on the linear relationship between the frequency shift, strain and temperature, the distance between the position where the strain occurs in the optical fiber 11 and the monitoring element 13 can be obtained, thereby obtaining the strain distribution and temperature distribution in the measured pipeline 200. By performing temperature compensation on the strain of the measured pipeline 200, the strain amount of the measured pipeline 200 and the strain position along the axial direction of the measured pipeline 200 can be obtained.

[0051] The linear relationship between stress strain and the temperature of the optical fiber 11 and the frequency shift of the Brillouin backscattered light in the optical fiber 11 is:

[0052]

[0053] The relationship between the frequency shift of the Brillouin backscattered light in the optical fiber 11 and the temperature of the optical fiber 11 is:

[0054]

[0055] After deducting the temperature effect, the relationship between the frequency shift of the Brillouin backscattered light in the optical fiber 11 and the stress and strain of the optical fiber 11 is:

[0056]

[0057] Where Δv B(Δε, ΔT) is the frequency shift variation of the Brillouin backscattered light in the optical fiber 11 under the action of strain and temperature, Δv B (0) is the initial frequency shift of the Brillouin backscattered light in the optical fiber 11, Δε is the strain acting on the optical fiber 11 sensor, and ΔT is the temperature of the optical fiber 11.

[0058] The beneficial effects of the strain monitoring system 100 provided by the present application are as follows: compared with the prior art, the strain monitoring system 100 of the present application is filled with a filling body 12 between the inner wall of the monitoring channel 15 and the optical fiber 11. On the one hand, when the measured pipeline 200 is strained, the strain of the measured pipeline 200 can be transmitted to the optical fiber 11 through the filling body 12, thereby improving the average strain transmission efficiency in the process of transmitting the strain from the measured pipeline 200 to the optical fiber 11, so that the strain monitoring system 100 provided by the present application can accurately monitor the strain amount, thereby making the strain monitoring system 100 provided by the present application have the advantage of high monitoring accuracy; on the other hand, the filling body 12 is filled in the monitoring channel 15, so that the strain of the measured pipeline 200 can be extended in the monitoring channel 15. The strain of the inner wall of the measured pipe 200 and the strain of the outer wall of the measured pipe 200 can be transmitted to the optical fiber 11 in the monitoring channel 15, so that the strain monitoring system 100 provided by the present application can accurately locate the stress concentration position, thereby making the strain monitoring system 100 provided by the present application have the advantage of higher monitoring accuracy; thirdly, the monitoring channel 15 is arranged between the inner wall of the measured pipe 200 and the outer wall of the measured pipe 200. When the measured pipe 200 is under pressure, the strain of the inner wall of the measured pipe 200 and the strain of the outer wall of the measured pipe 200 can be transmitted to the optical fiber 11 in the monitoring channel 15, so that the strain monitoring system 100 provided by the present application can simultaneously monitor the strain of the inner wall of the measured pipe 200 and the strain of the outer wall of the measured pipe 200, thereby making the strain monitoring system 100 provided by the present application have the advantage of higher monitoring accuracy.

[0059] In some embodiments provided in the present application, the material of the filling body 12 may be a fluid, and the filling material of the filling body 12 may be injected into the monitoring channel 15 by a grouting method, and the filling material may solidify in the monitoring channel 15 to form the filling body 12 .

[0060] As a result, the fluid has a high fluidity, which facilitates the filling material of the filling body 12 to flow in the monitoring channel 15 and fully fill the monitoring channel 15, so that the filling body 12 formed after the filling material is solidified can be completely filled between the optical fiber 11 and the inner wall of the monitoring channel 15.

[0061] In some embodiments provided in the present application, there are multiple monitoring channels 15, the monitoring channels 15 extend along the axial direction of the measured pipeline 200, and the multiple monitoring channels 15 are arranged at intervals along the circumference of the measured pipeline 200, such as Figure 1 As shown, there are multiple optical fibers 11 , and the multiple optical fibers 11 are arranged in a one-to-one correspondence in the monitoring channel 15 .

[0062] Specifically, multiple monitoring channels 15 are arranged in parallel and spaced apart along the circumference of the measured pipeline 200, and an optical fiber 11 is provided in each monitoring channel 15, and the multiple optical fibers 11 are connected to the monitoring element 13. Therefore, by setting up multiple monitoring channels 15 and multiple optical fibers 11 to monitor the strain distribution of the measured pipeline 200 along its circumference, the blind spots of the strain monitoring system 100 provided in the present application for strain monitoring of the measured pipeline 200 are reduced, and strain monitoring of any position of the measured pipeline 200 is achieved.

[0063] In some embodiments provided in the present application, the multiple optical fibers 11 include a first optical fiber 111 and a second optical fiber 112, the monitoring device 13 is suitable for monitoring the strain of the measured pipeline 200 through the first optical fiber 111, and the monitoring device 13 is suitable for monitoring the temperature of the measured pipeline 200 through the second optical fiber 112 to compensate for the strain of the first optical fiber 111.

[0064] Specifically, the multiple optical fibers 11 are divided into a first optical fiber 111 and a second optical fiber 112. The first optical fiber 111 is only used to monitor the strain of the measured pipeline 200, and the second optical fiber 112 is only used to monitor the temperature of the measured pipeline 200, thereby eliminating part of the strain of the measured pipeline 200 caused by temperature according to the temperature of the measured pipeline 200, and then obtaining part of the strain of the measured pipeline 200 caused by stress, thereby eliminating the influence of temperature on the strain monitoring system 100 provided in the present application, and improving the monitoring accuracy of the strain monitoring system 100 provided in the present application.

[0065] like Figure 1 As shown, in some embodiments provided in the present application, there are multiple first optical fibers 111 and one second optical fiber 112, and the multiple first optical fibers 111 are evenly spaced along the circumference of the measured pipeline 200, so that the strain distribution of the measured pipeline 200 along its circumference can be obtained based on the multiple first optical fibers 111.

[0066] In some embodiments provided in the present application, the strain monitoring system 100 further includes a pre-buried pipe 14 , which is cast between the inner wall of the measured pipeline 200 and the outer wall of the measured pipeline 200 , and a monitoring channel 15 is formed in the pre-buried pipe 14 .

[0067] Specifically, the embedded pipe 14 can be a 14mm aluminum-plastic composite pipe. The measured pipe 200 is formed by pouring concrete. Before pouring the measured pipe 200, the embedded pipe 14 is placed at a preset position. When pouring the measured pipe 200, the concrete is coated on the outer peripheral side of the measured pipe 200 and solidified, so that the embedded pipe 14 is fixed between the inner wall of the measured pipe 200 and the outer wall of the measured pipe 200, thereby forming a monitoring channel 15 on the inner side of the embedded pipe 14 to facilitate the arrangement of the optical fiber 11.

[0068] Therefore, by setting up the pre-buried tube 14, on the one hand, the difficulty of arranging the monitoring channel 15 can be reduced, thereby reducing the processing cost of the strain monitoring system 100 provided in the present application; on the other hand, the inner wall of the pre-buried tube 14 is relatively smooth, which facilitates the arrangement of the optical fiber 11 in the monitoring channel 15.

[0069] In some other embodiments provided in the present application, a through hole is provided in the measured pipeline 200, and the through hole is located between the inner wall of the measured pipeline 200 and the outer wall of the measured pipeline 200, and the through hole penetrates the measured pipeline 200 along the axial direction of the measured pipeline 200, and a monitoring channel 15 is formed in the through hole.

[0070] Therefore, the inner wall of the monitoring channel 15 is the pipe body of the measured pipe 200. When the measured pipe 200 is strained, the transmission efficiency of the strain of the measured pipe 200 to the optical fiber 11 is improved, thereby improving the monitoring accuracy of the strain monitoring system 100 provided in the present application.

[0071] In some embodiments provided in this application, Figure 1 As shown, the measured pipeline 200 includes a plurality of pipe segments 21 , which are assembled along the x-direction and the outer peripheral sides of the x-direction to form the measured pipeline 200 , and the monitoring channel 15 passes through the plurality of pipe segments 21 along the x-direction.

[0072] The embedded pipe 14 is arranged in the pipe segment 21 and penetrates the pipe segment 21 along the axial direction of the pipe segment 21. Each pipe segment 21 includes one or more embedded pipes 14. When multiple pipe segments 21 are spliced ​​to form the pipeline 200 to be tested, multiple embedded pipes 14 in multiple pipe segments 21 can be inserted along the axial direction of the pipe segment 21. Figure 1 The monitoring channel 15 is formed by splicing in the x direction.

[0073] Therefore, by splicing multiple pipe segments 21 to form the measured pipeline 200, the difficulty of processing the monitoring channel 15 in the multiple pipe segments 21 is reduced, thereby improving the processing quality such as the straightness and surface roughness of the monitoring channel 15, and further facilitating the arrangement of the optical fiber 11 in the monitoring channel 15.

[0074] In some embodiments provided in the present application, the ratio of the elastic modulus of the filling body 12 to the elastic modulus of the measured pipe 200 is 0.25-0.35.

[0075] Specifically, the elastic modulus of the filling body 12 is smaller than the elastic modulus of the measured pipeline 200, and the ratio of the elastic modulus of the filling body 12 to the elastic modulus of the measured pipeline 200 can be any value between 0.25 and 0.35. Optionally, the elastic modulus of the filling body 12 is 10 GPa, and the elastic modulus of the measured pipeline 200 is 34 GPa.

[0076] Therefore, the elastic modulus of the filling body 12 is only 0.25-0.35 times that of the measured pipeline 200, so that the rigidity of the filling body 12 is much smaller than the rigidity of the measured pipeline 200. When the measured pipeline 200 is strained, the strain of the measured pipeline 200 can be transmitted to the optical fiber 11 through the filling body 12, thereby avoiding the misalignment and slippage between the filling body 12 and the inner wall of the monitoring channel 15 caused by the excessive rigidity of the filling body 12, which affects the strain transmission.

[0077] In some embodiments provided in the present application, the tested pipeline 200 is made of reinforced concrete, and the filling body 12 is formed by solidifying cement paste.

[0078] Specifically, the material selection of the filler 12 takes into account that the average strain transfer rate increases with the elastic modulus of the filler 12 and eventually tends to be stable. Cement paste is used as the material of the filler 12, and the elastic modulus of the filler 12 is about 10 GPa, so that the average strain transfer rate of the filler 12 can meet the strain monitoring requirements.

[0079] The strain transfer formula between the core matrix of the optical fiber 11 and the filler 12 formed after the cement paste is cured is:

[0080]

[0081] Among them, ε (x) is the core strain of optical fiber 11, ε n is the filler body 12 strain formed after the cement paste solidifies, E l is the elastic modulus of the core of optical fiber 11, E i is the elastic modulus of the filler 12 formed after the cement paste is solidified, G i is the shear modulus of the filler 12 formed after the cement paste is solidified, γ i is the radius of the filling body 12 formed after the cement paste is solidified, and L is the length of the optical fiber 11.

[0082] In some embodiments provided in the present application, the strain monitoring system 100 further includes a bracket, which is connected to the optical fiber 11 , and the bracket can be supported in the monitoring channel 15 so that the optical fiber 11 extends along the axis of the monitoring channel 15 .

[0083] Specifically, there are multiple brackets, and the multiple brackets are arranged at intervals along the length direction of the optical fiber 11, so that the multiple brackets are also arranged at intervals in the monitoring channel 15, and the multiple brackets can be supported against the inner wall of the monitoring channel 15, such as Figure 2 As shown, the optical fiber 11 is located at the central axis of the axial cross section of the monitoring channel 15.

[0084] Therefore, the optical fiber 11 is located at the central axis of the axial section of the monitoring channel 15. When the strain is transmitted from any position in the inner wall of the monitoring channel 15 to the optical fiber 11, the distance over which the strain is transmitted from the inner wall of the monitoring channel 15 to the optical fiber 11 is the same, thereby reducing the error of the strain monitoring system 100 provided in the present application in the radial direction of the monitoring channel 15, thereby enabling the strain monitoring system 100 provided in the present application to have the advantage of higher monitoring accuracy.

[0085] Combine the following Figure 1 , Figure 2 and Figure 3 The construction method of the strain monitoring system 100 provided in the present application is described. The construction method of the strain monitoring system 100 includes:

[0086] A monitoring channel 15 is provided between the inner wall of the measured pipeline 200 and the outer wall of the measured pipeline 200;

[0087] Place the optical fiber 11 into the monitoring channel 15 along the extension direction of the monitoring channel 15;

[0088] Filling material is injected into the monitoring channel 15 , and the filling material is solidified and filled into the monitoring channel 15 .

[0089] Specifically, the monitoring channel 15 penetrates the measured pipeline 200 along the axial direction of the measured pipeline 200, so that the optical fiber 11 can be placed in the monitoring channel 15 by using the high-pressure airflow generated by the air blower. The filling material is a solidifiable fluid, and the grouting technology is used to inject the filling material in a fluid state into the monitoring channel 15 and make the filling material fully fill the space between the optical fiber 11 and the inner wall of the monitoring channel 15, so that the filling material is still fully filled between the inner wall of the monitoring channel 15 and the optical fiber 11 after solidification.

[0090] The beneficial effect of the construction method of the strain monitoring system 100 provided in the present application is that, compared with the prior art, the strain monitoring system 100 of the present application fills the filling material between the inner wall of the monitoring channel 15 and the optical fiber 11, and the filling material is still fully filled between the inner wall of the monitoring channel 15 and the optical fiber 11 after solidification.

[0091] On the one hand, the pipe body of the measured pipe 200 and the optical fiber 11 are fully in contact with each other by the filling material. When the measured pipe 200 is strained, the strain of the measured pipe 200 can be transmitted to the optical fiber 11 through the filling material, thereby improving the average strain transmission efficiency in the process of transmitting the strain from the measured pipe 200 to the optical fiber 11, so that the strain monitoring system 100 constructed by the construction method of the strain monitoring system 100 provided by the present application can accurately monitor the strain amount and has the advantage of high monitoring accuracy; on the other hand, the filling body 12 is filled in the monitoring channel 15, so that the strain of the measured pipe 200 can be transmitted to the optical fiber 11 at any point in the extension direction of the monitoring channel 15, so that the strain monitoring system 100 provided by the present application can be accurately monitored. The strain monitoring system 100 constructed by the construction method of the strain monitoring system 100 can accurately locate the stress concentration position and has the advantage of high monitoring accuracy; thirdly, the monitoring channel 15 is arranged between the inner wall of the measured pipeline 200 and the outer wall of the measured pipeline 200. When the measured pipeline 200 is under pressure, the strain of the inner wall of the measured pipeline 200 and the strain of the outer wall of the measured pipeline 200 can be transmitted to the optical fiber 11 in the monitoring channel 15, so that the strain monitoring system 100 constructed by the construction method of the strain monitoring system 100 provided in the present application can simultaneously monitor the strain of the inner wall of the measured pipeline 200 and the strain of the outer wall of the measured pipeline 200 and has the advantage of high monitoring accuracy.

[0092] In some embodiments provided in the present application, a monitoring channel 15 is provided between the inner wall and the outer wall of the measured pipeline 200, including:

[0093] Performing a loading test on the tested pipeline 200 to determine the radial position where stress concentration occurs in the tested pipeline 200;

[0094] A monitoring channel 15 is provided at a radial position where stress concentration occurs in the measured pipeline 200.

[0095] Specifically, when the tested pipe 200 is loaded, the strain of the tested pipe 200 will be concentrated on the inner side of the pipe body of the tested pipe 200, that is, the strain of the tested pipe 200 is concentrated between the inner wall of the tested pipe 200 and the outer wall of the tested pipe 200. By performing a loading test on the tested pipe 200, such as Figure 3 As shown, the distance L1 between the position where the strain of the measured pipeline 200 is concentrated and the inner wall of the measured pipeline 200 and the distance L2 between the position where the strain of the measured pipeline 200 is concentrated and the outer wall of the measured pipeline 200 are determined.

[0096] Therefore, the axis of the monitoring channel 15 is set at the position where the strain is concentrated when the measured pipeline 200 is strained, that is, the optical fiber 11 in the monitoring channel 15 passes through the position where the strain is concentrated when the measured pipeline 200 is strained, thereby improving the sensitivity of the optical fiber 11 to the strain of the measured pipeline 200 when the measured pipeline 200 is strained, thereby improving the monitoring accuracy of the strain monitoring system 100 constructed by the construction method of the strain monitoring system 100 provided in the present application.

[0097] In some embodiments provided in the present application, the tested pipeline 200 includes a plurality of segments 21, and a loading test is performed on the tested pipeline 200 to determine a radial position where stress concentration occurs in the tested pipeline 200, including:

[0098] One or more pipe segments 21 are randomly selected from the tested pipeline 200, and a loading test is performed on the pipe segments 21;

[0099] According to the radial position of the pipe segment 21 when it fails under loading, the radial position where stress concentration occurs in the tested pipeline 200 is determined.

[0100] Specifically, the plurality of segments 21 are arranged along Figure 1 The x direction and Figure 1 The outer peripheral side of the middle x direction is spliced ​​to form the measured pipeline 200, and the monitoring channel 15 is along Figure 1 The plurality of pipe segments 21 are passed through in the middle x direction. Thus, the strain concentration position of the measured pipeline 200 is obtained by performing a pressure test on the plurality of pipe segments 21. On the one hand, the difficulty of the pressure test can be reduced. On the other hand, when the measured pipeline 200 is under pressure, a single pipe segment 21 serves as the smallest pressure-bearing unit. The position accuracy of the strain concentration position of the measured pipeline 200 is improved by performing a pressure test on the plurality of pipe segments 21. This improves the monitoring accuracy of the strain monitoring system 100 constructed by the construction method of the strain monitoring system 100 provided in the present application.

[0101] In some embodiments provided in the present application, the optical fiber 11 is placed into the monitoring channel 15 along the extension direction of the monitoring channel 15, and further includes:

[0102] Connect a plurality of brackets (not shown in the figure) to the optical fiber 11;

[0103] Place the optical fiber 11 together with a plurality of brackets into the monitoring channel 15;

[0104] The bracket is supported against the inner wall of the monitoring channel 15 so that the optical fiber 11 extends along the axis of the monitoring channel 15;

[0105] A pre-tensioning force is applied to the optical fiber 11 to keep the optical fiber 11 straight in the monitoring channel 15 .

[0106] Specifically, there are multiple optical fibers 11, including a first optical fiber 111 and a second optical fiber 112. The first optical fiber 111 is used to monitor the stress and strain of the measured pipeline 200, and the second optical fiber 112 is used to monitor the temperature strain of the measured pipeline 200. A pre-tightening force is applied to the first optical fiber 111 so that the first optical fiber 111 always extends in a straight direction when the filling material is injected into the monitoring channel 15, thereby avoiding stress monitoring failure of the strain monitoring system 100 provided in the present application due to bending of the optical fiber 11.

[0107] Therefore, the optical fiber 11 is located at the central axis of the axial section of the monitoring channel 15. When the strain is transmitted from any position in the inner wall of the monitoring channel 15 to the optical fiber 11, the distance over which the strain is transmitted from the inner wall of the monitoring channel 15 to the optical fiber 11 is the same, thereby reducing the error of the strain monitoring system 100 provided in the present application in the radial direction of the monitoring channel 15, thereby enabling the strain monitoring system 100 provided in the present application to have the advantage of higher monitoring accuracy.

[0108] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A strain monitoring system for monitoring the strain of a measured pipeline, characterized in that: The strain monitoring system comprises: A monitoring channel and an optical fiber, wherein the monitoring channel is arranged between the inner wall of the measured pipeline and the outer wall of the measured pipeline, the optical fiber is partially arranged in the monitoring channel and extends along the monitoring channel, and a filling body is further arranged in the monitoring channel, the filling body is filled between the optical fiber and the inner wall of the monitoring channel, and the filling body is suitable for transmitting the strain of the measured pipeline to the optical fiber; A monitoring component is connected to the optical fiber to monitor the strain of each position of the optical fiber along the length direction of the optical fiber.

2. The strain monitoring system according to claim 1, characterized in that: There are a plurality of monitoring channels, which extend along the axial direction of the measured pipeline and are arranged at intervals along the circumferential direction of the measured pipeline. There are a plurality of optical fibers, which are arranged in a one-to-one correspondence in the monitoring channels.

3. The strain monitoring system according to claim 2, characterized in that: The plurality of optical fibers include a first optical fiber and a second optical fiber. The monitoring device is suitable for monitoring the strain of the measured pipeline through the first optical fiber. The monitoring device is suitable for monitoring the temperature of the measured pipeline through the second optical fiber to compensate for the strain of the first optical fiber.

4. The strain monitoring system according to any one of claims 1 to 3, characterized in that: It also includes a pre-buried pipe, which is cast between the inner wall of the measured pipeline and the outer wall of the measured pipeline, and the monitoring channel is formed in the pre-buried pipe.

5. The strain monitoring system according to claim 1, characterized in that: The ratio of the elastic modulus of the filling body to the elastic modulus of the measured pipeline is 0.25-0.35; And / or, the filling body is formed by solidifying cement paste.

6. The strain monitoring system according to claim 1, characterized in that: The measured pipeline includes a plurality of pipe segments, and the monitoring channel penetrates the plurality of pipe segments along the axial direction of the measured pipeline.

7. A construction method of a strain monitoring system, characterized in that: include: A monitoring channel is provided between the inner wall of the measured pipeline and the outer wall of the measured pipeline; Placing an optical fiber into the monitoring channel along an extension direction of the monitoring channel; Filling material is injected into the monitoring channel, and the filling material is solidified to form a filling body filled in the monitoring channel, and the filling body is suitable for transmitting the strain of the measured pipeline to the optical fiber.

8. The construction method according to claim 7, characterized in that: A monitoring channel is set between the inner wall and the outer wall of the measured pipeline, including: Performing a loading test on the tested pipeline to determine the radial position where stress concentration occurs in the tested pipeline; The monitoring channel is arranged at a radial position where stress concentration occurs in the measured pipeline.

9. The construction method according to claim 7, characterized in that: The pipeline under test includes a plurality of segments, and a loading test is performed on the pipeline under test to determine a radial position where stress concentration occurs in the pipeline under test, including: Randomly select one or more of the segments in the tested pipeline and perform a loading test on the segments; According to the radial position of the pipe segment when it fails under loading, the radial position where stress concentration occurs in the measured pipeline is determined.

10. The construction method according to claim 7, characterized in that: Placing the optical fiber into the monitoring channel along the extension direction of the monitoring channel, further comprising: Connecting a plurality of brackets to the optical fiber; Placing the optical fiber together with the plurality of brackets into the monitoring channel; The bracket is supported against the inner wall of the monitoring channel so that the optical fiber extends along the axis of the monitoring channel; A pre-tensioning force is applied to the optical fiber to keep the optical fiber straight in the monitoring channel.

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