Prestressed duct friction resistance measuring method and measuring system based on weak grating fiber

Abstract

The invention relates to the technical field of prestress construction, in particular to a prestress duct friction resistance measuring method and system based on weak grating optical fibers. Comprising the following steps: during steel strand production, selecting a plurality of steel strands, and implanting weak grating optical fibers into the steel strands to form optical fiber steel strands; when a steel strand is installed, at least one steel strand with optical fibers is installed in a prestressed duct in a concrete beam, and a tensioning end system and an anchoring end system are arranged at the two ends of the installed steel strand; the weak grating optical fiber is connected with an optical fiber demodulator, and a tensioning end system is used for carrying out graded loading on the steel strand; and recording a tension value monitored by each strain grating measuring point, and calculating a pore friction resistance coefficient and a pore deviation coefficient based on the tension values. The measuring method provided by the invention is very simple and very accurate, does not need to purchase a pressure sensor additionally, has low requirements on test conditions, and can be suitable for any prestressed duct shape.

Description

Technical Field

[0001] The present application relates to the field of prestressed construction technology, and specifically refers to a method and system for measuring friction resistance of a prestressed hole based on weak grating optical fiber. Background Art

[0002] With the development of prestressing technology, the span of bridges is getting longer and longer, and the corresponding prestressed channel length is also getting longer and longer. In the prestressed construction of bridges, the longer the channel, the more difficult it is to locate, the greater the deviation between the channel line shape and the design, and the unevenness of the channel material and the number of joints also increase, which ultimately leads to a large difference between the channel friction coefficient μ and the channel deviation coefficient k of the prestressed channel design and the actual situation.

[0003] In order to obtain the actual friction coefficient μ and deviation coefficient k of the prestressed channel and improve the control level of prestressed construction, an on-site prestressed channel friction test is generally carried out. The test is mainly based on active and passive jacks. This method mainly reverses the channel friction μ and k by measuring the prestress loss of the channel. The test adopts a method of alternating one end as the tensioning end and the other end as the anchoring end. That is, after completing a jack tensioning to the designed tonnage, the jack oil pump gradually returns oil to 0, the tensioning end and the anchoring end are exchanged, and the tensioning is repeated step by step, and the data is recorded. Finally, the jack returns oil, the tensioning devices at both ends are removed, and the test of one channel is completed.

[0004] The current prestressed hole friction test method is cumbersome and can only obtain the friction of the test hole. However, the actual hole styles are various and the lengths are different. Therefore, the actual measured hole friction coefficient μ and hole deviation coefficient k cannot strictly represent other holes with significantly different shapes. In addition, in order to improve the measurement accuracy, the existing method generally requires the purchase of additional pressure sensors, which is costly. Summary of the invention

[0005] The purpose of this application is to address the deficiencies of the above-mentioned background technology and to provide a method and system for measuring the friction resistance of a prestressed hole based on weak grating optical fiber.

[0006] The technical solution of the present application is: a method for measuring friction resistance of a prestressed hole based on weak grating optical fiber, comprising:

[0007] During the production of steel strands, several steel strands are selected and implanted with weak grating optical fibers to form steel strands with optical fibers. The weak grating optical fibers are arranged along the entire length of the steel strands and multiple strain grating measuring points are evenly arranged along the length direction of the weak grating optical fibers.

[0008] When installing the steel strand, at least one steel strand with optical fiber is installed in the prestressed channel in the concrete beam, and a tensioning end system and an anchoring end system are arranged at both ends of the installed steel strand;

[0009] Connect the weak grating optical fiber to the optical fiber demodulator, and use the tensioning end system to load the steel strands in stages;

[0010] The tensile force value monitored at each strain grating measuring point is recorded, and the hole friction coefficient and hole deviation coefficient are calculated based on the tensile force value.

[0011] According to a method for measuring friction of a prestressed hole based on weak grating optical fiber provided in the present application, the method of selecting a plurality of steel strands and implanting weak grating optical fiber to form a steel strand with optical fiber includes: implanting the weak grating optical fiber into the center position of the steel strand to form a steel strand with optical fiber.

[0012] According to a method for measuring friction resistance of a prestressed channel based on weak grating optical fiber provided in the present application, the method for installing at least one steel strand with optical fiber in a prestressed channel in a concrete beam includes: at least one steel strand with optical fiber in the prestressed channel in the concrete beam is located at the center of all steel strands.

[0013] According to a method for measuring prestressed channel friction resistance based on weak grating optical fiber provided in the present application, the method for calculating the channel friction resistance coefficient and the channel deviation coefficient based on the tension value includes: constructing the relationship between the tension value of any two strain grating measuring points on the weak grating optical fiber and the channel friction resistance coefficient and the channel deviation coefficient as follows:

[0014]

[0015] Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber;

[0016] P i+1 ——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber;

[0017] l i,i+1 ——The length of the prestressed channel between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber;

[0018] θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line;

[0019] μ——hole friction coefficient;

[0020] k——pore deviation coefficient;

[0021] The tension values ​​of multiple strain grating measuring points are combined and solved according to the above formula to obtain the channel friction coefficient and channel deviation coefficient.

[0022] According to a prestressed hole friction measurement method based on weak grating optical fiber provided in the present application, the distance between adjacent strain grating measurement points on the weak grating optical fiber is 0.2m to 1m.

[0023] The present application also provides a prestressed hole friction measurement system based on weak grating optical fiber, comprising:

[0024] Steel strands, the steel strands being passed through prestressed channels in concrete beams;

[0025] An optical fiber module, wherein the optical fiber module comprises a weak grating optical fiber implanted in at least one steel strand; the weak grating optical fiber is arranged along the entire length of the steel strand and a plurality of strain grating measuring points are evenly arranged along the length direction of the weak grating optical fiber;

[0026] A tensioning module, the tensioning module is connected to a section of the steel strand for performing graded loading on the steel strand;

[0027] An anchoring module, the anchoring module is connected to the other end of the steel strand to fix the steel strand;

[0028] A signal receiving module, wherein the signal receiving module comprises an optical fiber demodulator; the optical fiber demodulator is connected to a weak grating optical fiber signal;

[0029] A calculation module is provided, wherein the calculation module calculates the hole friction coefficient and the hole deviation coefficient based on the tension value monitored by each strain grating measuring point.

[0030] According to a prestressed hole friction measurement system based on weak grating optical fiber provided in the present application, the optical fiber module includes a plurality of steel strands with optical fiber; a weak grating optical fiber is implanted at the center position of the steel strands with optical fiber.

[0031] According to a prestressed hole friction measurement system based on weak grating optical fiber provided in the present application, the optical fiber module includes at least one steel strand with optical fiber located at the center of all steel strands.

[0032] According to a prestressed hole friction measurement system based on weak grating optical fiber provided by the present application, the calculation module includes:

[0033] A relationship building module, wherein the relationship building module builds the relationship between the tension value of any two strain grating measuring points on the weak grating optical fiber and the channel friction coefficient and the channel deviation coefficient according to the following formula:

[0034]

[0035] Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber;

[0036] P i+1——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber;

[0037] l i,i+1 ——The length of the prestressed channel between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber;

[0038] θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line;

[0039] μ——hole friction coefficient;

[0040] k——pore deviation coefficient;

[0041] The result acquisition module is used to combine the tensile force values ​​of multiple strain grating measurement points and solve the hole friction coefficient and the hole deviation coefficient according to the above formula.

[0042] According to a prestressed hole friction measurement system based on weak grating optical fiber provided by the present application, the distance between adjacent strain grating measurement points on the weak grating optical fiber is 0.2m to 1m.

[0043] The advantages of the present application are as follows: 1. The present application implants weak grating optical fibers in the steel strands, and uses the weak grating optical fibers to collect the tension value during the tensioning process of the steel strands. The weak grating optical fibers are arranged along the entire length of the steel strands, and multiple tension values ​​can be collected evenly and densely, and the channel friction coefficient and channel deviation coefficient can be calculated very quickly. Compared with the traditional measurement method, the present application only needs to test a bundle of prestressed channels to obtain the required channel friction coefficient and channel deviation coefficient. The measurement method is simpler and more accurate, and there is no need to purchase additional pressure sensors. The test conditions are low and can be applied to any prestressed channel shape. The test method is fast and convenient for engineering projects to accept;

[0044] 2. This application implants the weak grating optical fiber into the center of the steel strand so that the weak grating optical fiber can accurately collect the tension value of the steel strand during the tensioning process. At the same time, the weak grating optical fiber is at the center of the steel strand. During the tensioning and arrangement of the steel strand, the steel strand will protect the weak grating optical fiber and is not easily damaged.

[0045] 3. The present application arranges the steel strand with optical fiber at the center of all the steel strands. This position can represent the prestressing tensioning process of the steel strand to the greatest extent, making the final calculation result more accurate.

[0046] 4. This application calculates the channel friction coefficient and the channel deviation coefficient by constructing the relationship between the tension value of the two strain grating measuring points and the channel friction coefficient and the channel deviation coefficient. The constructed formula is very simple, and it is very convenient to calculate the channel friction coefficient and the channel deviation coefficient. The calculation results can be obtained quickly, and the calculation results are accurate, and the calculation efficiency is also greatly improved;

[0047] 5. By setting the arrangement spacing of the strain grating measuring points, the present application can enable the weak grating optical fiber to uniformly and densely collect the tension value of the steel strand. The collected data is rich and uniform, which facilitates the subsequent calculation of the channel friction coefficient and the channel deviation coefficient.

[0048] The measurement method of the present application is very simple. By testing a bundle of prestressed channels, the required channel friction coefficient and channel deviation coefficient can be obtained. The measurement method is extremely accurate and does not require the purchase of additional pressure sensors. It has low requirements for test conditions and can be applied to any prestressed channel shape. The test method is quick and easy to accept for engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 : Schematic diagram of the friction measurement of the prestressed hole of the present application;

[0050] Among them: 1—tensioning end system; 2—concrete beam; 3—prestressed channel; 4—steel strand with optical fiber; 5—steel strand; 6—anchoring end system. DETAILED DESCRIPTION

[0051] The embodiments of the present application are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0052] In the description of the present application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying 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.

[0053] 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0054] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0055] The present application relates to a method for measuring friction resistance of a prestressed channel based on weak grating optical fiber. The present application is to tension the steel strands of the prestressed channel that passes through the concrete beam, apply load to the steel strands, use the weak grating optical fiber in the steel strands to record the tension value of the steel strands during the tensioning process, and then analyze the tension value to calculate the channel friction coefficient and channel deviation coefficient corresponding to the prestressed channel. Compared with the traditional measurement method, the measurement method of the present application only needs to test a bundle of prestressed channels to obtain the required channel friction coefficient and channel deviation coefficient, and because weak grating optical fiber is used to monitor the tension value, there is no need to purchase additional pressure sensors during the measurement process, the test conditions are low, and it can be applied to any prestressed channel shape. The test method is fast and rapid, and the test results are extremely accurate.

[0056] Specifically, Figure 1 As shown, the prestressed hole friction measurement method based on weak grating optical fiber of the present application can be carried out according to the following steps:

[0057] S1. When producing steel strands 5, select a number of steel strands and implant weak grating optical fibers to form steel strands with optical fibers 4. The weak grating optical fibers are arranged along the entire length of the steel strands and multiple strain grating measuring points are evenly arranged along the length direction of the weak grating optical fibers.

[0058] The present application directly implants a weak grating optical fiber into the steel strand, and the weak grating optical fiber will subsequently pass through the prestressed channel 3 along with the steel strand. During the tensioning process of the steel strand, the weak grating optical fiber will also be tensioned along with the steel strand 5, so the weak grating optical fiber can clearly collect the tension value borne by the steel strand 5;

[0059] The distance between adjacent strain grating measuring points on the weak grating optical fiber is 0.2m to 1m, which can be set according to the actual application requirements and is not limited to the above values;

[0060] S2. When installing the steel strand 5, at least one steel strand 4 with optical fiber is installed in the prestressed channel 3 in the concrete beam 2, and a tensioning end system 1 and an anchoring end system 6 are arranged at both ends of the installed steel strand 5;

[0061] Among the bundle of steel strands passing through the prestressed channel 3, at least one steel strand is implanted with a weak grating optical fiber, that is, a steel strand with optical fiber 4 is formed. Because the weak grating optical fiber is arranged along the entire length of the steel strand, and a plurality of strain grating measuring points are arranged on the weak grating optical fiber, the tension values ​​at a plurality of positions along the length direction of the steel strand can be uniformly collected without configuring other strain sensors.

[0062] The anchoring end system 6 anchors one end of the steel strand 5, and the tensioning end system 1 connects the other end of the steel strand 5 and applies a load to the steel strand 5;

[0063] S3, connecting the weak grating optical fiber to the optical fiber demodulator, and using the tensioning end system 1 to perform graded loading on the steel strand 5;

[0064] The optical fiber demodulator is connected to the weak grating optical fiber signal, and the signal collected by the weak grating optical fiber is transmitted to the optical fiber demodulator, which processes the collected signal and converts it into a corresponding tension value;

[0065] S4, recording the tension value monitored by each strain grating measuring point, and calculating the hole friction coefficient and the hole deviation coefficient based on the tension value;

[0066] Experiments have shown that there is a corresponding functional relationship between the tension value of the prestressed steel strand and the friction coefficient and deviation coefficient of the prestressed channel. As long as the tension value of the prestressed steel strand is obtained, the friction coefficient and deviation coefficient of the channel can be obtained through the constructed functional relationship.

[0067] In some embodiments of the present application, the present embodiment optimizes the above-mentioned step S1. Specifically, the method of selecting a plurality of steel strands 5 and implanting weak grating optical fibers to form steel strands 4 with optical fibers is as follows: selecting a plurality of steel strands 5 and implanting weak grating optical fibers into the center of the steel strands to form steel strands 4 with optical fibers. The weak grating optical fibers are located at the center of the steel strands 5, and can accurately collect the tension value of the steel strands 5 during the tensioning process. At the same time, the weak grating optical fibers are located at the center of the steel strands 5. During the tensioning and arrangement of the steel strands 5, the steel strands 5 will protect the weak grating optical fibers and are not easily damaged.

[0068] In other embodiments of the present application, this embodiment optimizes the above step S2, such as Figure 1 As shown, the method for installing at least one steel strand 4 with optical fiber into the prestressed channel 3 in the concrete beam 2 is as follows: at least one steel strand 4 with optical fiber in the prestressed channel 3 in the concrete beam 2 is located at the center of all the steel strands 5 .

[0069] The optical fiber-carrying steel strand 4 is located at the center of all the steel strands, and can represent the prestressed tensioning process that the steel strands undergo during the tensioning process to the greatest extent. The weak grating optical fiber at this position can accurately obtain the tension value of the steel strand 5 during the tensioning process, which can facilitate the subsequent accurate acquisition of the channel friction coefficient and the channel deviation coefficient.

[0070] In a further embodiment of the present application, the present embodiment optimizes the above-mentioned step S4. Specifically, the method for calculating the channel friction coefficient and the channel deviation coefficient based on the tension value includes: constructing the relationship between the tension value of any two strain grating measuring points on the weak grating optical fiber and the channel friction coefficient and the channel deviation coefficient as follows:

[0071]

[0072] Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber;

[0073] P i+1 ——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber;

[0074] l i,i+1 ——The length of the prestressed channel 3 between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber is approximately equal to the spacing between two strain grating measuring points;

[0075] θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line;

[0076] μ——hole friction coefficient;

[0077] k——pore deviation coefficient;

[0078] The tension values ​​of multiple strain grating measuring points are combined and solved according to the above formula to obtain the channel friction coefficient and channel deviation coefficient.

[0079] The i+1th strain grating measuring point on the weak grating optical fiber and the ith strain grating measuring point on the weak grating optical fiber may be two adjacent strain grating measuring points or two non-adjacent strain grating measuring points.

[0080] In actual measurement, when the steel strand 5 is produced, several steel strands are selected to be implanted with weak grating optical fibers to form steel strands with optical fibers 4, and the weak grating optical fibers are implanted in the center of the steel strands to form steel strands with optical fibers 4. The weak grating optical fibers are arranged along the entire length of the steel strands, and multiple strain grating measuring points are evenly arranged along the length direction of the weak grating optical fibers. When the steel strand 5 is installed, at least one steel strand 4 with optical fibers is installed in the prestressed channel 3 in the concrete beam 2, and at least one steel strand 4 with optical fibers in the prestressed channel 3 in the concrete beam 2 is located at the center of all the steel strands 5. A tensioning end system 1 and an anchoring end system 6 are arranged at both ends of the installed steel strand 5. The weak grating optical fiber is connected to the optical fiber demodulator, and the steel strand 5 is graded loaded by the tensioning end system 1. The tension value monitored by each strain grating measuring point is recorded, and the relationship between the tension value of any two strain grating measuring points on the weak grating optical fiber and the channel friction coefficient and the channel deviation coefficient is constructed as follows:

[0081]

[0082] Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber;

[0083] P i+1 ——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber;

[0084] l i,i+1 ——The length of the prestressed channel 3 between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber is approximately equal to the spacing between two strain grating measuring points;

[0085] θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line;

[0086] μ——hole friction coefficient;

[0087] k——pore deviation coefficient;

[0088] The tension values ​​of multiple strain grating measuring points are combined and solved according to the above formula to obtain the channel friction coefficient and channel deviation coefficient.

[0089] In addition, the present application also relates to a prestressed channel friction measurement system based on weak grating optical fiber, including a steel strand 5, an optical fiber module, a tensioning module, an anchoring module, a signal receiving module and a computing module, wherein the steel strand 5 is passed through a prestressed channel 3 in a concrete beam 2; the optical fiber module includes a weak grating optical fiber implanted in at least one steel strand, the weak grating optical fiber is arranged along the entire length of the steel strand and a plurality of strain grating measuring points are evenly arranged along the length direction of the weak grating optical fiber; the tensioning module is connected to a section of the steel strand 5 for graded loading of the steel strand 5; the anchoring module is connected to the other end of the steel strand 5 for fixing the steel strand 5; the signal receiving module includes an optical fiber demodulator, which is connected to the weak grating optical fiber signal; the computing module calculates the channel friction coefficient and the channel deviation coefficient based on the tension value monitored by each strain grating measuring point.

[0090] The optical fiber module comprises a plurality of steel strands 4 with optical fibers, and a weak grating optical fiber is implanted at the center of the steel strands 4 with optical fibers.

[0091] The optical fiber module includes at least one steel strand 4 with optical fiber located at the center of all the steel strands 5 .

[0092] The calculation module includes a relationship building module and a result acquisition module. The relationship building module builds the relationship between the tensile force values ​​of any two strain grating measuring points on the weak grating optical fiber and the channel friction coefficient and channel deviation coefficient according to the following formula:

[0093]

[0094] Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber;

[0095] P i+1 ——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber;

[0096] l i,i+1 ——The length of the prestressed channel 3 between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber;

[0097] θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line;

[0098] μ——hole friction coefficient;

[0099] k——pore deviation coefficient;

[0100] The result acquisition module is used to combine the tensile force values ​​of multiple strain grating measuring points and solve the hole friction coefficient and hole deviation coefficient according to the above formula.

[0101] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application to be protected. The scope of protection claimed in the present application is defined by the attached claims and their equivalents.

Claims

1. A method for measuring friction resistance of a prestressed hole based on weak grating optical fiber, characterized in that: include, When producing the steel strand (5), a number of steel strands are selected and implanted with weak grating optical fibers to form a steel strand with optical fibers (4), the weak grating optical fibers are arranged along the entire length of the steel strand, and a plurality of strain grating measuring points are evenly arranged along the length direction of the weak grating optical fibers; When installing the steel strand (5), at least one steel strand (4) with optical fiber is installed in the prestressed channel (3) in the concrete beam (2), and a tensioning end system (1) and an anchoring end system (6) are arranged at both ends of the installed steel strand (5); The weak grating optical fiber is connected to the optical fiber demodulator, and the steel strand (5) is subjected to designed graded loading using the tensioning end system (1); The tensile force value monitored at each strain grating measuring point is recorded, and the hole friction coefficient and hole deviation coefficient are calculated based on the tensile force value.

2. A method for measuring friction resistance of a prestressed hole based on weak grating optical fiber as claimed in claim 1, characterized in that: The method of selecting a plurality of steel strands (5) and implanting weak grating optical fibers to form a steel strand with optical fibers (4) comprises: implanting the weak grating optical fibers into the center of the steel strands to form the steel strand with optical fibers (4).

3. A method for measuring friction resistance of a prestressed hole based on weak grating optical fiber as claimed in claim 1, characterized in that: The method for installing at least one steel strand (4) with optical fiber in a prestressed hole (3) in a concrete beam (2) comprises: at least one steel strand (4) with optical fiber in the prestressed hole (3) in the concrete beam (2) is located at the center of all steel strands (5).

4. A method for measuring friction resistance of a prestressed hole based on weak grating optical fiber as claimed in claim 1, characterized in that: The method for calculating the channel friction coefficient and the channel deviation coefficient based on the tension value includes: constructing the relationship between the tension values ​​of any two strain grating measurement points on the weak grating optical fiber and the channel friction coefficient and the channel deviation coefficient as follows: Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber; P i+1 ——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber; l i,i+1 ——the length of the prestressed channel (3) between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber; θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line; μ——hole friction coefficient; k——pore deviation coefficient; The tension values ​​of multiple strain grating measuring points are combined and solved according to the above formula to obtain the channel friction coefficient and channel deviation coefficient.

5. A method for measuring friction resistance of a prestressed hole based on weak grating optical fiber as claimed in claim 1, characterized in that: The distance between adjacent strain grating measuring points on the weak grating optical fiber is 0.2m to 1m.

6. A prestressed hole friction measurement system based on weak grating optical fiber, characterized by: The measuring system is operated according to any one of the prestressed hole friction measurement methods based on weak grating optical fiber as described in claims 1 to 5, including: A steel strand (5), wherein the steel strand (5) is inserted into a prestressed channel (3) in a concrete beam (2); An optical fiber module, wherein the optical fiber module comprises a weak grating optical fiber implanted in at least one steel strand; the weak grating optical fiber is arranged along the entire length of the steel strand and a plurality of strain grating measuring points are evenly arranged along the length direction of the weak grating optical fiber; A tensioning module, the tensioning module being connected to a section of the steel strand (5) for performing graded loading on the steel strand (5); An anchoring module, the anchoring module being connected to the other end of the steel strand (5) for fixing the steel strand (5); A signal receiving module, wherein the signal receiving module comprises an optical fiber demodulator; the optical fiber demodulator is connected to a weak grating optical fiber signal; A calculation module is provided, wherein the calculation module calculates the hole friction coefficient and the hole deviation coefficient based on the tension value monitored by each strain grating measuring point.

7. A prestressed hole friction measurement system based on weak grating optical fiber as claimed in claim 6, characterized in that: The optical fiber module comprises a plurality of steel strands (4) with optical fibers; a weak grating optical fiber is implanted at the center of the steel strands (4) with optical fibers.

8. A prestressed hole friction measurement system based on weak grating optical fiber as claimed in claim 7, characterized in that: The optical fiber module comprises at least one steel strand (4) with optical fiber located at the center of all the steel strands (5).

9. A prestressed hole friction measurement system based on weak grating optical fiber as claimed in claim 6, characterized in that: The calculation module includes: A relationship building module, wherein the relationship building module builds the relationship between the tension value of any two strain grating measuring points on the weak grating optical fiber and the channel friction coefficient and the channel deviation coefficient according to the following formula: Where: P i ——The tension value of the i-th strain grating measuring point on the weak grating optical fiber; P i+1 ——The tension value of the i+1th strain grating measuring point on the weak grating optical fiber; l i,i+1 ——the length of the prestressed channel (3) between the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber; θ i,i+1 ——The angle between the line connecting the i-th strain grating measuring point and the i+1-th strain grating measuring point on the weak grating optical fiber and the horizontal line; μ——hole friction coefficient; k——pore deviation coefficient; The result acquisition module is used to combine the tensile force values ​​of multiple strain grating measurement points and solve the hole friction coefficient and the hole deviation coefficient according to the above formula.

10. A prestressed hole friction measurement system based on weak grating optical fiber as claimed in claim 6, characterized in that: The distance between adjacent strain grating measuring points on the weak grating optical fiber is 0.2m to 1m.

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