GFRP sensing rib and preparation method and performance monitoring method thereof

Abstract

The invention provides a GFRP sensing rib and a preparation method and a performance monitoring method thereof, and belongs to the technical field of sensors. The graphene water-based acrylic resin composite material is used as the sensing layer of the GFRP sensing rib, water-based acrylic resin and resin in the GFRP sensing rib have good compatibility and adhesiveness, and the integration degree of the GFRP sensing rib is high. In addition, the graphene has a relatively large specific surface area and is easily dispersed in a resin matrix to form a stable conductive network; when the GFRP sensing rib is used as a sensing layer, the resistance of the whole graphene conductive network changes, so that the strain value of a measured structure can be obtained only by measuring the resistance of the GFRP sensing rib after the relation between the resistance change rate and the strain is established, and the GFRP sensing rib has high sensitivity and large measuring range.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a GFRP sensor rib and a preparation method and a performance monitoring method thereof. Background Art

[0002] Pile foundations have been widely used in various construction projects due to their high bearing capacity, good stability and strong adaptability. However, since pile foundations are underground hidden projects, they are easily affected by geological conditions. At the same time, the construction of pile foundations is difficult and has high technical requirements, which makes it difficult to ensure the quality and safety of pile foundations. Therefore, using appropriate monitoring methods to quantitatively analyze the internal forces of pile foundations is an important way to judge the quality of pile foundations and an indispensable part of the construction process.

[0003] At present, the most common monitoring method for pile foundation is to directly stick traditional monitoring devices such as resistance strain gauges, soil pressure gauges, and sliding micrometers on the surface of the pile body, and quantitatively analyze the internal force of the pile foundation through the values ​​obtained by monitoring. However, the above monitoring methods have many disadvantages, such as resistance strain gauges are greatly affected by the environment, have a small range, many leads, and are prone to zero drift; soil pressure gauges have high requirements for layout technology and are difficult to construct; and sliding micrometer test data are susceptible to human interference. At the same time, it is difficult to bury such monitoring devices in underground environments, and even if they are successfully laid, it is difficult to achieve long-term monitoring. At present, the method of using the steel bars in the pile foundation as a monitoring carrier includes sticking a steel bar meter on the surface of the steel bar, tying a fiber grating, and burying a fiber grating string after slotting the steel bar. However, the steel bar meter is greatly affected by soil disturbance, has poor measurement accuracy, and low stability; the fiber grating is fragile and easy to damage, and slotting will have an irreversible effect on the strength and elastic modulus of the steel bar; and the degree of integration of such measurement devices and the measured components is not high.

[0004] GFRP bars are made of multiple strands of continuous glass fibers bonded through a matrix material (such as polyamide resin, polyethylene resin, epoxy resin, etc.) and then extruded and drawn through a special mold. GFRP bars not only have the advantages of high strength, light weight, and good electromagnetic insulation, but most importantly, they have high corrosion resistance in harsh environments and can replace steel bars as monitoring carrier components. However, when traditional monitoring devices are placed on GFRP bars and replace steel bars as monitoring carriers, there is also the problem of low integration between the measuring device and the measured component, which leads to problems such as small detection range, low sensitivity, and poor sensing performance.

[0005] Therefore, there is an urgent need to provide a GFRP sensor bar with a large measuring range, high sensitivity and good sensing performance. Summary of the invention

[0006] The object of the present invention is to provide a GFRP sensing rib and a preparation method and a performance monitoring method thereof. The GFRP sensing rib provided by the present invention has the advantages of a large measuring range, high sensitivity and good sensing performance.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a GFRP sensor rib, comprising a GFRP rib, a sensor layer and a packaging layer arranged in sequence from the inside to the outside; two ends of the sensor layer are respectively fixed with connecting wires;

[0009] The material of the sensing layer is a graphene water-based acrylic resin composite material.

[0010] Preferably, in the graphene water-based acrylic resin composite material, the mass ratio of graphene to water-based acrylic resin is 1 to 2.5:100.

[0011] Preferably, conductive silver paste is coated between the wire and the sensing layer.

[0012] Preferably, the encapsulation layer is made of water-based acrylic resin.

[0013] The present invention also provides a method for preparing the GFRP sensor rib described in the above technical solution, comprising the following steps:

[0014] (1) coating the graphene aqueous acrylic resin mixture on the outer surface of the GFRP bar, performing a first curing reaction, and obtaining a GFRP bar wrapped with a sensing layer;

[0015] (2) fixing connecting wires at both ends of the GFRP reinforcement wrapped around the sensing layer obtained in step (1) to obtain a connecting wire GFRP reinforcement;

[0016] (3) Coating a packaging material on the outer surface of the sensing layer of the GFRP rib of the connecting wire obtained in step (2) and performing a second curing reaction to obtain a GFRP sensing rib.

[0017] Preferably, the method for preparing the graphene aqueous acrylic resin mixed solution in step (1) comprises: mixing the graphene aqueous dispersion with the aqueous acrylic resin to obtain the graphene aqueous acrylic resin mixed solution.

[0018] Preferably, the mass of graphene in the graphene aqueous acrylic resin mixed solution accounts for 1 to 2.5% of the mass of the aqueous acrylic resin.

[0019] Preferably, the temperature of the first curing reaction in step (1) is 50-60° C., and the time of the first curing reaction is 15-30 min.

[0020] Preferably, the temperature of the second curing reaction in step (3) is 50-60° C., and the time of the second curing reaction is 15-30 min.

[0021] The present invention also provides a method for monitoring the performance of a GFRP sensor bar, comprising the following steps:

[0022] (a) A resistance strain gauge is attached near the end of the sensing layer of the GFRP sensor rib, and then a tensile test is performed to collect the strain value and resistance value generated during the stretching process, and a resistance change rate-strain relationship diagram of the GFRP sensor rib is drawn with the strain value as the horizontal axis and the resistance change rate as the vertical axis; the GFRP sensor rib is the GFRP sensor rib described in the above technical solution or the GFRP sensor rib prepared by the preparation method described in the above technical solution;

[0023] (b) Using the GFRP sensor bars in the pile foundation to monitor the resistance change rate of the GFRP sensor bars in the pile foundation, and monitoring the strain data of the GFRP sensor bars in the pile foundation based on the resistance change rate-strain relationship diagram obtained in step (a).

[0024] The present invention provides a GFRP sensor rib, comprising a GFRP rib, a sensor layer and a packaging layer arranged in sequence from the inside to the outside; two ends of the sensor layer are respectively fixed with connecting wires; the material of the sensor layer is a graphene water-based acrylic resin composite material. The present invention uses the graphene water-based acrylic resin composite material as the sensor layer of the GFRP sensor rib, and the water-based acrylic resin has good compatibility and adhesion with the resin in the GFRP sensor rib, so that the GFRP sensor rib has a high degree of integration, which is conducive to improving the sensitivity and stability of the GFRP sensor rib. The invention adds graphene because graphene has a large specific surface area and is easy to disperse in the resin matrix. The mutually free graphene sheets overlap each other to form a stable conductive network. When it is used as a sensing layer, when the resin matrix is ​​strained within a certain range, the graphene sheet moves accordingly. On the one hand, the direct contact area between the graphene sheets changes, and on the other hand, the relative position of the sheet forming the quantum tunneling effect changes, so that the resistance of the entire graphene conductive network changes. After establishing the relationship between the resistance change rate and the strain, the strain value of the measured structure can be obtained by measuring the resistance of the GFRP sensing rib. In addition, the GFRP sensing rib provided by the invention also inherits the advantage of the high strength of the GFRP rib and has a large monitoring range. The results of the embodiment show that the GFRP sensing rib provided by the invention has good sensing performance, a large measurement range, and a sensitive response, and even very small resistance changes can be monitored. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A top view of the GFRP sensor rib provided by the present invention;

[0026] exist Figure 1 Middle: 1 is GFRP rib; 2 is sensing layer; 3 is conductive silver paste; 4 is wire; 5 is packaging layer;

[0027] Figure 2 A position relationship diagram of various parts of the GFRP sensor rib provided by the present invention;

[0028] exist Figure 2 Middle: 1 is GFRP rib; 2 is sensing layer; 3 is conductive silver paste; 4 is wire; 5 is packaging layer;

[0029] Figure 3 is the pasting position of the resistance strain gauge in Example 1 of the present invention;

[0030] Figure 4 This is a resistance change rate-strain relationship diagram drawn for Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention provides a GFRP sensor rib, comprising a GFRP rib, a sensor layer and a packaging layer arranged in sequence from the inside to the outside; two ends of the sensor layer are respectively fixed with connecting wires;

[0032] The material of the sensing layer is a graphene water-based acrylic resin composite material.

[0033] The present invention has no special limitation on the source and size of the GFRP bars, and any conventional commercially available GFRP bars may be used.

[0034] In the present invention, the material of the sensing layer is a graphene water-based acrylic resin composite material. The present invention uses a graphene water-based acrylic resin composite material as a sensing layer, and the water-based acrylic resin can improve the integration of the GFRP sensing ribs; and graphene has a large specific surface area, and is easily dispersed in a resin matrix, and can form a stable conductive network in the resin; when it is used as a sensing layer, when the resin matrix is ​​strained within a certain range, the graphene sheet moves accordingly, on the one hand, the direct contact area between the graphene sheets changes, and on the other hand, the relative position of the sheet forming the quantum tunneling effect changes, so that the resistance of the entire graphene conductive network changes, and then after establishing the relationship between the resistance change rate and the strain, the strain value of the measured structure can be obtained by measuring the resistance of the GFRP sensing ribs.

[0035] The present invention has no special limitation on the size of the graphene, and any conventional commercially available graphene or graphene prepared by a conventional method may be used.

[0036] The present invention does not specifically limit the model of the water-based acrylic acid, and any conventional commercially available water-based acrylic acid may be used. In an embodiment of the present invention, the water-based acrylic acid may be NCT-212 produced by Changzhou Carbon Boxin Material Technology Co., Ltd.

[0037] In the present invention, in the graphene water-based acrylic resin composite material, the mass ratio of graphene to water-based acrylic resin is preferably 1 to 2.5: 100, more preferably 2: 100. The present invention controls the amount of the two within the above range, which is more conducive to improving the sensing and sensitivity of the GFRP sensor rib.

[0038] The present invention does not impose any special limitation on the thickness of the sensing layer, and the thickness can be adjusted as required so that the outer surface of the GFRP bar can be evenly wrapped with the sensing layer.

[0039] In the present invention, the material of the encapsulation layer is preferably water-based acrylic resin. The present invention uses water-based acrylic resin as the encapsulation layer, which can protect the sensing layer, prevent the sensing layer from being corroded during use, maintain the sensitivity of the GFRP sensing ribs and extend the service life of the GFRP sensing ribs.

[0040] The present invention does not impose any special limitation on the thickness of the encapsulation layer, and the thickness can be adjusted as required so that the sensing layer can be completely covered and wrapped.

[0041] In the present invention, connecting wires are fixed at both ends of the sensing layer. The present invention can be used to monitor the resistance change rate of the GFRP sensing ribs by fixing the connecting wires.

[0042] In the present invention, the method for fixing the connecting wire is preferably a winding method. The present invention winds the wire on the sensing layer, so that the wire can be fixed on the sensing layer.

[0043] In the present invention, a conductive silver paste is preferably coated between the wire and the sensing layer. The present invention can avoid the error caused by the point contact formed by the wire being tied to the GFRP bar by preferentially coating the conductive silver paste between the wire and the sensing layer, thereby improving the accuracy of the monitoring result. The present invention does not specifically limit the model of the conductive silver paste, and any conventional commercially available product can be used. In an embodiment of the present invention, the model of the conductive silver paste can be 3703 of Suzhou Xinwei High-tech Materials Co., Ltd., with a concentration of 50±5%.

[0044] The top view of the GFRP sensor rib provided by the present invention is as follows: Figure 1 As shown; the position relationship diagram of each part of the GFRP sensor rib is as follows Figure 2 As shown. Figure 1 and 2 In the figure, 1 is GFRP rib; 2 is sensing layer; 3 is conductive silver paste; 4 is wire; and 5 is packaging layer.

[0045] The present invention also provides a method for preparing the GFRP sensor rib described in the above technical solution, comprising the following steps:

[0046] (1) coating the graphene aqueous acrylic resin mixture on the outer surface of the GFRP bar, performing a first curing reaction, and obtaining a GFRP bar wrapped with a sensing layer;

[0047] (2) fixing connecting wires at both ends of the GFRP reinforcement wrapped around the sensing layer obtained in step (1) to obtain a connecting wire GFRP reinforcement;

[0048] (3) Coating a packaging material on the outer surface of the sensing layer of the GFRP rib of the connecting wire obtained in step (2) and performing a second curing reaction to obtain a GFRP sensing rib.

[0049] The present invention coats the graphene aqueous acrylic resin mixed liquid on the outer surface of the GFRP bar, performs a first curing reaction, and obtains the GFRP bar wrapped with the sensing layer.

[0050] In the present invention, the method for preparing the graphene aqueous acrylic resin mixed solution preferably comprises: mixing the graphene aqueous dispersion with the aqueous acrylic resin to obtain the graphene aqueous acrylic resin mixed solution.

[0051] The present invention does not impose any particular limitation on the concentration of the graphene aqueous dispersion, as long as a uniformly dispersed graphene aqueous dispersion can be provided. In an embodiment of the present invention, the mass concentration of the graphene aqueous dispersion may be 2.5%.

[0052] In the present invention, the mass of graphene in the graphene aqueous acrylic resin mixture is preferably 1-2.5% of the mass of the aqueous acrylic resin, and more preferably 2%. The present invention controls the mass of graphene to the mass of the aqueous acrylic resin within the above range, which can make the GFRP sensing rib have better sensing properties.

[0053] In the present invention, the method for mixing the graphene aqueous dispersion and the aqueous acrylic resin is preferably: stirring and ultrasonicating the graphene aqueous dispersion and the aqueous acrylic resin in sequence to obtain a graphene aqueous acrylic resin mixed solution. The present invention does not specifically limit the rotation speed of the stirring, and it can be adjusted as needed. In an embodiment of the present invention, the stirring time can be 5 minutes. In the present invention, the ultrasonic instrument is preferably an ultrasonic cell disruptor, and the power of the ultrasound can be 300W; the ultrasound time is preferably 15 to 60 minutes, and more preferably 15 to 30 minutes. The present invention can mix under the above conditions to make the two fully dispersed and uniform.

[0054] The present invention has no special limitation on the coating method, and any conventional coating method can be used. In an embodiment of the present invention, the coating method can be brush coating.

[0055] The present invention has no particular limitation on the coating thickness of the graphene water-based acrylic resin mixed solution, as long as the thickness of the graphene water-based acrylic resin film can be as small as possible and the outer surface of the GFRP rib can be completely covered.

[0056] In the present invention, the temperature of the first curing reaction is preferably 50-60°C, more preferably 60°C; the time of the first curing reaction is preferably 15-30 minutes, more preferably 20 minutes. The present invention forms a sensing layer by curing the graphene water-based acrylic resin at the above temperature.

[0057] After the GFRP bars wrapping the sensing layer are obtained, the present invention fixes connecting wires at both ends of the GFRP bars wrapping the sensing layer to obtain the connecting wire GFRP bars.

[0058] In the present invention, the method for fixing the connecting wire is preferably: coating conductive silver paste on both ends of the GFRP ribs wrapping the sensing layer, and then respectively winding two wires on the conductive silver paste after thermal curing.

[0059] The present invention does not specifically limit the coating length of the conductive silver paste, and it can be adjusted as needed to fill the space between the sensing layer and the wire with the conductive silver paste and cover the sensing layer as little as possible. In an embodiment of the present invention, the length of the conductive silver paste can be 1 cm.

[0060] In the present invention, the temperature of the thermal curing is preferably 90-150° C., more preferably 120° C. The present invention has no particular limitation on the time of the thermal curing, as long as the conductive silver paste can be completely cured into a solid. In an embodiment of the present invention, the thermal curing device can be a heat gun.

[0061] The present invention preferably coats the packaging material at the winding wire and solidifies it. In the present invention, the packaging material is preferably a water-based acrylic resin. The present invention is more conducive to fully fixing the wire at both ends of the GFRP ribs that wrap the sensing layer by coating the packaging material at the winding wire and solidifying it.

[0062] After obtaining the connecting wire GFRP rib, the present invention coats the outer surface of the sensing layer of the connecting wire GFRP rib with a packaging material, and performs a second curing reaction to obtain the GFRP sensing rib.

[0063] In the present invention, the encapsulating material is preferably water-based acrylic resin.

[0064] The present invention has no special limitation on the coating method and the coating amount of the packaging material, as long as the sensing layer can be completely covered with the packaging material.

[0065] In the present invention, the temperature of the second curing reaction is preferably 50-60°C, more preferably 60°C; the time of the second curing reaction is preferably 15-30 minutes, more preferably 20 minutes. The present invention forms an encapsulation layer by curing the water-based acrylic resin at the above temperature.

[0066] The preparation method provided by the invention is simple to operate and can obtain GFRP sensing ribs with a large measuring range, high sensitivity and good sensing performance.

[0067] The present invention also provides a method for monitoring the performance of a GFRP sensor bar, comprising the following steps:

[0068] (a) A resistance strain gauge is attached near the end of the sensing layer of the GFRP sensor tendon, and then a tensile test is performed to collect the strain value and resistance value generated during the stretching process. The resistance change rate-strain relationship diagram of the GFRP sensor tendon is drawn with the strain value as the horizontal axis and the resistance change rate as the vertical axis;

[0069] (b) Using the GFRP sensor bars in the pile foundation to monitor the resistance change rate of the GFRP sensor bars in the pile foundation, and monitoring the strain data of the GFRP sensor bars in the pile foundation based on the resistance change rate-strain relationship diagram obtained in step (a).

[0070] The present invention adheres a resistance strain gauge near the end of the sensing layer of the GFRP sensing rib, and then performs a tensile test to collect the strain value and resistance value generated during the stretching process, and draws a resistance change rate-strain relationship diagram of the GFRP sensing rib with the strain value as the horizontal coordinate and the resistance change rate as the vertical coordinate.

[0071] In the present invention, the GFRP sensor rib is the GFRP sensor rib described in the above technical solution or the GFRP sensor rib prepared by the preparation method described in the above technical solution.

[0072] In the present invention, the sticking position of the resistance strain gauge is located near the end of the sensing layer of the GFRP sensing rib. In an embodiment of the present invention, the sticking position of the resistance strain gauge is as follows: Figure 3 The present invention is more conducive to accurately collecting the resistance stress changes of the GFRP sensing rib during the stretching process by pasting the resistance strain gauge.

[0073] The present invention has no special limitation on the operation method of the tensile test, and any conventional tensile test method can be used. In an embodiment of the present invention, the tensile test device can be a universal testing machine WAW-1000.

[0074] The present invention has no special limitation on the device for collecting the strain value generated during the stretching process, and any conventional experimental device can be used. In an embodiment of the present invention, the device for collecting the strain value generated during the stretching process can be a strain collector, model JM3813; the device for collecting the resistance value generated during the stretching process can be a DC resistance tester, model 8246B.

[0075] The present invention collects the strain value and resistance value generated during the stretching process, and plots the resistance change rate-strain relationship diagram of the GFRP sensor rib with the strain value as the horizontal coordinate and the resistance change rate as the vertical coordinate. The present invention uses this diagram as a database for monitoring the GFRP sensor rib.

[0076] After obtaining the resistance change rate-strain relationship diagram of the GFRP sensing bar, the present invention uses the GFRP sensing bar in the pile foundation to monitor the resistance change rate in the GFRP sensing bar in the pile foundation, and monitors the strain data of the GFRP sensing bar in the pile foundation according to the resistance change rate-strain relationship diagram.

[0077] The present invention has no special limitation on the method of using the GFRP sensor reinforcement in pile foundation, and any conventional application method may be used.

[0078] Since the GFRP sensor bar provided by the present invention has the advantages of large measurement range, high sensitivity and good sensing performance, after determining the resistance change rate-strain relationship diagram of the GFRP sensor bar, when it is used in the pile foundation, it is only necessary to measure the resistance change rate of the GFRP sensor bar to obtain the corresponding strain data, thereby realizing rapid, sensitive and accurate monitoring of the GFRP sensor bar.

[0079] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] Example 1

[0081] A GFRP sensing rib, which comprises a GFRP rib, a sensing layer and an encapsulation layer from the inside to the outside; two ends of the sensing layer are respectively fixed with connecting wires; the sensing layer is made of a graphene water-based acrylic resin composite material, wherein the mass ratio of graphene to water-based acrylic resin in the graphene water-based acrylic resin composite material is 2:100; the encapsulation layer is made of water-based acrylic resin;

[0082] The preparation method of the above GFRP sensor rib is as follows:

[0083] (1) 16 g of a graphene aqueous dispersion with a solid content of 2.5% was taken and added to 20 g of an aqueous acrylic resin (NCT-212). The mixture was stirred with a glass rod for 5 min, and then the mixture was transferred to an ultrasonic cell disruptor and ultrasonically dispersed at a power of 300 W for 15 min to obtain a graphene aqueous acrylic resin mixture with a mass fraction of 2%. The surface of the GFRP bar was wiped with cotton dipped in alcohol to remove surface impurities; a brush with a length of 10 mm and a width of 5 mm was used to evenly and as thinly as possible apply the graphene aqueous acrylic resin mixture to the calibration section of the GFRP bar surface, and then the GFRP bar was placed in an oven and cured at 60° C. for 20 min to obtain a GFRP bar wrapped with a sensing layer;

[0084] (2) coating the two ends of the GFRP bar wrapped with the sensing layer obtained in step (1) with a conductive silver paste (type 3703) of about 1 cm in length, and accelerating the curing of the conductive silver paste with a hot air gun at a temperature of 120° C. After the conductive silver paste is cured, tying the wires at the places coated with the conductive silver paste, coating the wires with water-based acrylic resin, and curing them in an oven at a temperature of 60° C. to obtain the GFRP bar for connecting the wires;

[0085] (3) The outer surface of the sensing layer of the GFRP rib of the connecting wire obtained in step (2) is coated with water-based acrylic resin using a brush, and the mixture is cured at 60° C. for 20 minutes. After the water-based acrylic resin is cured, the GFRP sensing rib is obtained.

[0086] Example 2

[0087] A method for monitoring the performance of a GFRP sensor bar, comprising the following steps:

[0088] (a) Before the calibration test, the two ends of the GFRP sensor bar prepared in Example 1 with a length of 70 cm were anchored with a 23 cm steel pipe sleeve, and the middle test section was reserved for 24 cm. The anchoring can avoid shear damage at both ends of the GFRP sensor bar before it is broken. The calibration process is to stick a resistance strain gauge near the end of the GFRP sensor bar coated with graphene water-based acrylic resin, and put it into a universal testing machine for tensile test. The universal testing machine model for this tensile test is WAW-1000, the strain acquisition instrument model is JM3813, and the DC resistance tester model is 8246B. First, adjust the crossbeam of the universal testing machine to the appropriate position, place the GFRP sensor ribs in the center of the upper and lower clamps, and then clamp the jaws of the clamps to ensure that the jaws can clamp two-thirds of the length of the steel pipe sleeve while avoiding the bending of the GFRP ribs to generate reaction force that affects the test results; connect the strain gauge wires to the strain collector to collect the strain value generated during the stretching process, and connect the wires at both ends of the graphene water-based acrylic resin on the GFRP sensor ribs to the DC resistance tester to collect the change in resistance during the stretching process. This stretching test uses displacement control, and the size is set to 2mm / min until the GFRP sensor ribs break, and record the strain value and resistance change during the stretching process. Measure the resistance and calculate the resistance change rate through the resistance measuring instrument, measure the strain of the GFRP ribs through the strain collection box, and finally draw the resistance change rate-strain relationship diagram as shown below. Figure 4 As shown;

[0089] (b) Using the GFRP sensor bars in the pile foundation to monitor the resistance change rate of the GFRP sensor bars in the pile foundation, and monitoring the strain data of the GFRP sensor bars in the pile foundation based on the resistance change rate-strain relationship diagram obtained in step (a).

[0090] Test Case

[0091] The test results of the GFRP sensing ribs prepared in Example 1 and conventional sensors (resistance strain gauges and fiber grating sensors) are shown in Table 1:

[0092] Table 1 Comparison of common sensor ranges and sensor coefficients

[0093]

[0094] As can be seen from Table 1, the present invention has not only a larger range and a larger sensing coefficient than the resistance strain gauge, but also a larger range than the fiber Bragg grating sensor. This is because the GFRP sensing rib provided by the present invention uses a graphene water-based acrylic resin composite material as the sensing layer of the GFRP sensing rib, and the water-based acrylic resin has good compatibility and adhesion with the resin in the GFRP sensing rib, so that the GFRP sensing rib has a high degree of integration, which is beneficial to improve the sensitivity and stability of the GFRP sensing rib. In addition, since graphene has a large specific surface area, it is easy to form a stable conductive network in the resin matrix; when it is used as a sensing layer, when the resin matrix is ​​strained within a certain range, the graphene sheet moves accordingly, and the resistance of the entire graphene conductive network changes, and then after establishing the relationship between the resistance change rate and the strain, it is only necessary to measure the resistance of the GFRP sensing rib to obtain the strain value of the measured structure. The GFRP sensing rib provided by the present invention has excellent sensitivity and sensitivity, and inherits the advantages of the high strength of the GFRP rib, which can make the GFRP sensing rib have a larger monitoring range.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A GFRP sensor rib, comprising a GFRP rib, a sensor layer and a packaging layer arranged in sequence from the inside to the outside; two ends of the sensor layer are respectively fixed with connecting wires; The material of the sensing layer is a graphene water-based acrylic resin composite material.

2. The GFRP sensor bar according to claim 1, characterized in that: In the graphene water-based acrylic resin composite material, the mass ratio of graphene to water-based acrylic resin is 1 to 2.5:

100.

3. The GFRP sensor bar according to claim 1, characterized in that: Conductive silver paste is coated between the wire and the sensing layer.

4. The GFRP sensor bar according to claim 1, characterized in that: The material of the encapsulation layer is water-based acrylic resin.

5. The method for preparing the GFRP sensor rib according to any one of claims 1 to 4, comprising the following steps: (1) coating the graphene aqueous acrylic resin mixture on the outer surface of the GFRP bar, performing a first curing reaction, and obtaining a GFRP bar wrapped with a sensing layer; (2) fixing connecting wires at both ends of the GFRP reinforcement wrapped around the sensing layer obtained in step (1) to obtain a connecting wire GFRP reinforcement; (3) Coating an encapsulation material on the outer surface of the sensing layer of the GFRP rib of the connecting wire obtained in step (2) and performing a second curing reaction to obtain a GFRP sensing rib.

6. The preparation method according to claim 5, characterized in that: The method for preparing the graphene aqueous acrylic resin mixed solution in step (1) comprises: mixing a graphene aqueous dispersion with an aqueous acrylic resin to obtain a graphene aqueous acrylic resin mixed solution.

7. The preparation method according to claim 6, characterized in that: The mass of graphene in the graphene aqueous acrylic resin mixed solution accounts for 1-2.5% of the mass of the aqueous acrylic resin.

8. The preparation method according to claim 5, characterized in that: The temperature of the first curing reaction in step (1) is 50-60° C., and the time of the first curing reaction is 15-30 minutes.

9. The preparation method according to claim 5 or 8, characterized in that: The temperature of the second curing reaction in step (3) is 50-60° C., and the time of the second curing reaction is 15-30 minutes.

10. A method for monitoring the performance of a GFRP sensor bar, comprising the following steps: (a) a resistance strain gauge is attached near the end of the sensing layer of the GFRP sensor rib, and then a tensile test is performed to collect the strain value and resistance value generated during the stretching process, and a resistance change rate-strain relationship diagram of the GFRP sensor rib is drawn with the strain value as the horizontal axis and the resistance change rate as the vertical axis; the GFRP sensor rib is the GFRP sensor rib according to any one of claims 1 to 4 or the GFRP sensor rib prepared by the preparation method according to any one of claims 5 to 9; (b) Using the GFRP sensor bars in the pile foundation to monitor the resistance change rate of the GFRP sensor bars in the pile foundation, and monitoring the strain data of the GFRP sensor bars in the pile foundation based on the resistance change rate-strain relationship diagram obtained in step (a).

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