Intelligent sensor for monitoring quality and long-term performance of grouting sleeve and preparation and monitoring method

Abstract

The invention provides an intelligent sensor for monitoring quality and long-term performance of a grouting sleeve and a preparation and monitoring method. The intelligent sensor comprises a carbon fiber strip, a current electrode and a voltage electrode, current electrodes are respectively arranged at two ends of the carbon fiber strip, and a plurality of voltage electrodes are arranged on the surface of the carbon fiber strip; and the current electrode and the voltage electrode are respectively fixed by using a conductive material and are packaged by using epoxy resin. According to the invention, non-destructive detection can be realized, the integrity and safety of the structure can be maintained, and meanwhile, the sleeve structure state real-time self-sensing and damage self-monitoring functions are provided, so that monitoring data can be quickly obtained; by utilizing the unique material advantages of the carbon fiber, the sensor is corrosion-resistant and fatigue-resistant, the monitoring result has high sensitivity, the sensor has better self-sensing characteristic for structural defects and non-uniformity, grouting defects caused in construction can be accurately positioned, and the structural damage state can be monitored in real time. In addition, the intelligent sensor is high in environmental adaptability, simple in design and easy and convenient to operate, and extra monitoring equipment is not needed.

Description

Technical Field

[0001] The invention belongs to the technical field of prefabricated buildings, and in particular relates to an intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve and a preparation and monitoring method thereof. Background Art

[0002] In recent years, with the advancement of building industrialization, prefabricated buildings have gradually become an important development direction of the construction industry. Prefabricated buildings are assembled on site through prefabricated components in factories, and have the advantages of short construction period, controllable quality, environmental protection and energy saving. This construction method not only reduces the labor intensity and construction period of on-site construction, but also significantly reduces construction waste and environmental pollution. With the strong support of policies, prefabricated buildings have developed rapidly around the world. Especially in my country, prefabricated buildings are widely used in various building types such as residential buildings, office buildings, commercial complexes, etc., becoming a highlight of the construction industry. With the continuous advancement of technology and the increase in market demand, prefabricated buildings are gradually moving towards standardization, modularization and intelligence, further enhancing their application prospects and market competitiveness.

[0003] In prefabricated buildings, sleeve grouting is a commonly used connection method. This method reserves a sleeve at the connection part of the prefabricated component and injects high-strength grouting material into the sleeve on site to make the connection part reach the required strength and stability. The process of sleeve grouting connection includes steps such as sleeve positioning, grouting material injection and curing, which can ensure the close connection and efficient force transmission of the connection part. Sleeve grouting connection can not only ensure the rapid installation and precise alignment of components, but also provide excellent mechanical properties to adapt to various complex construction environments and structural requirements. In addition, sleeve grouting connection has good seismic resistance and durability, and can meet the special needs of different projects. Therefore, the sleeve grouting connection method has been widely used in prefabricated buildings and has become an important means to improve the overall performance of buildings.

[0004] The density of grouting is directly related to the structural strength and durability of the connection. Insufficient density may lead to a decrease in the mechanical properties of the connection and even cause safety accidents. Therefore, accurate detection of the density of sleeve grouting is a key link in ensuring the quality and safety of prefabricated buildings.

[0005] At present, the mainstream detection methods mainly include non-destructive detection methods and destructive detection methods. Non-destructive detection methods include ultrasonic detection method, impact elastic wave detection method and X-ray detection method. Ultrasonic and impact elastic wave detection methods are greatly affected by the environment and operators; the equipment required for X-ray detection method is expensive and radioactive, so there are certain restrictions on its use. Destructive detection methods, such as the core drilling method, directly observe and measure the density of the core sample by drilling a core sample at the grouting site; the splitting method, by applying a certain splitting force to the grouting site, detects the tensile strength of the grouting material. These two methods will damage the integrity of the structure and are not often used in actual engineering. It can be seen that the above conventional detection methods have certain limitations.

[0006] On the other hand, due to the combined effects of the shrinkage of grouting materials and the long-term effects of various factors in the engineering environment, the performance of the grouting sleeve may gradually deteriorate during use, such as crack initiation and expansion, detachment and peeling of grouting materials, corrosion, material performance degradation, deformation and displacement, fatigue damage and interface cracking. These degradation phenomena will weaken the structural strength and durability of the sleeve, and damage its long-term bearing capacity and overall performance. Therefore, real-time monitoring of the grouting sleeve during service becomes particularly important. However, mainstream monitoring methods, such as regular visual inspections and non-destructive testing, have many limitations in actual engineering. Summary of the invention

[0007] In response to the above technical problems, the present invention provides an intelligent sensor for monitoring the quality and long-term performance of grouting sleeves. The sensor is based on carbon fiber and detects the quality of grouting sleeves during construction and monitors their long-term performance. The sensor can realize intelligent monitoring of the construction quality and real-time performance of the grouting sleeves of prefabricated structures.

[0008] The present invention also provides a method for preparing an intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve. The method is simple to operate, quick to prepare and low in cost.

[0009] The present invention also provides a monitoring method of an intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve. The method is easy to operate and has high economic efficiency. It can simultaneously monitor the quality and long-term performance of the grouting sleeve and determine the damage location. The method can be widely used in prefabricated buildings using grouting sleeves.

[0010] Note that the description of these objectives does not prevent the existence of other objectives. One embodiment of the present invention does not need to achieve all of the above objectives. Objectives other than the above objectives can be extracted from the description of the specification, drawings, and claims.

[0011] The present invention achieves the above technical objectives through the following technical means.

[0012] An intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve includes a carbon fiber strip, a current electrode and a voltage electrode;

[0013] Current electrodes are respectively arranged at both ends of the carbon fiber strip as end electrodes, and a plurality of voltage electrodes are arranged on the surface of the carbon fiber strip as surface electrodes; the current electrodes and the voltage electrodes are both fixed with conductive materials and encapsulated with epoxy resin.

[0014] In the above solution, the current electrodes and voltage electrodes are made of wires.

[0015] Furthermore, the wire is a tinned copper wire.

[0016] Furthermore, the conductive material is conductive silver paste.

[0017] Furthermore, the current electrode at one end of the carbon fiber strip is made of a tinned copper wire bonded to one end of the carbon fiber strip by conductive silver glue. The tinned copper wire is arranged on the carbon fiber strip in a winding manner and pasted with conductive silver glue to form a number of equidistantly arranged voltage electrodes until it is wound to the other end of the carbon fiber strip. The tinned copper wire and the carbon fiber strip are bonded with conductive silver glue to form the current electrode at the other end of the carbon fiber strip.

[0018] In the above scheme, the width-to-length ratio of the carbon fiber strip is in the range of 0.05 to 0.2, the thickness is 1 to 1.2 mm, and the sensitivity and linearity are good.

[0019] A method for preparing the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve comprises the following steps:

[0020] Step S1: Use sandpaper to polish the two ends of the carbon fiber strip and the surface electrode arrangement location, and then use acetone to wipe it after polishing to remove dust and resin on the surface;

[0021] Step S2: a tinned copper wire is attached to one end of the carbon fiber strip and bonded with a conductive silver glue to form a current electrode. After one end is fixed, the tinned copper wire is equally wound on the surface of the carbon fiber strip in a spiral form and bonded with a conductive silver glue to form a plurality of voltage electrodes. The tinned copper wire is bonded to the carbon fiber strip with a conductive silver glue to form a current electrode at the other end of the carbon fiber strip.

[0022] Step S3: After the conductive silver glue is cured, epoxy resin is used to seal the conductive silver glue-coated area. After the epoxy resin is cured, the smart sensor is prepared.

[0023] A monitoring method based on the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve comprises the following steps:

[0024] Define the angle between the smart sensor and the axial direction of the grouting sleeve as θ, and arrange the smart sensor around the grouting sleeve along the angle θ; apply a thin layer of epoxy resin on the position where the smart sensor is arranged, and stick the smart sensor on the thin layer of epoxy resin; after the epoxy resin is cured, it can be used to detect the grouting density of the grouting sleeve, that is, the quality of the grouting sleeve.

[0025] The above scheme also includes the following steps:

[0026] By hammering the grouting sleeve with qualified construction quality, the first three standard strain modal vibration modes of the grouting sleeve are obtained; the strain modal vibration modes obtained by the change of voltage electrode resistance are compared with the standard strain modal vibration modes. Any order of strain modal vibration mode can reflect the construction quality of the grouting sleeve, and the other two orders of strain modal vibration modes can be used for verification; the damage condition of the grouting sleeve is obtained by the resistance change of each voltage electrode to monitor the long-term performance of the grouting sleeve.

[0027] Further, the following steps are included:

[0028] Step S1: Arrange the smart sensor on the grouting sleeve with good grouting density; then connect the current electrode of the smart sensor to the driving end of the resistance tester through a wire, take another wire to connect the voltage electrode to be tested to the detection end of the resistance tester, turn on the resistance tester to start recording the real-time resistance of the smart sensor; test and obtain the initial resistance R of each measuring section i , i = 1, 2, 3 ... n, n is a positive integer; hammer the grouting sleeve with a hammer to obtain the resistance change ΔR of each measuring section i , i = 1, 2, 3...n, n is a positive integer; the axial strain of the grouting sleeve is calculated using the following formula:

[0029]

[0030] in:

[0031] ε is the axial strain of the grouting sleeve;

[0032] θ is the angle between the smart sensor and the axial direction of the grouting sleeve;

[0033] μ is the Poisson’s ratio of the smart sensor;

[0034] ΔR i is the resistance change of the smart sensor;

[0035] K θ is the strain sensitivity coefficient when the angle between the intelligent sensor and the grouting sleeve axis is θ;

[0036] R i is the initial resistance of the smart sensor;

[0037] The strain mode of the grouting sleeve is determined by analyzing the resistance change of each measuring section, and the resistance change ΔR i The first three strain modal vibration modes of the grouting sleeve with good density are obtained by fitting and normalization. This strain modal vibration mode is the standard strain modal vibration mode.

[0038] Step S2: Arrange the intelligent sensor on the grouting sleeve of the grouting density to be tested, repeat the operation in step S1 to obtain the first three-order strain modal vibration modes of the grouting sleeve to be tested, and compare the first three-order strain modal vibration modes of the grouting sleeve to be tested with the standard strain modal vibration modes; since the mass and stiffness and other structural physical parameters of the defective part of the sleeve grouting are different from those of the dense part, its natural frequency will change, which is reflected by the strain modal vibration mode; compare the first-order strain modal vibration mode of each measuring section, if there is a sudden change in the comparison between the measuring section and the standard strain modal vibration mode, it means that there is a defect in the grouting within this test range; compare the second-order and third-order strain modal vibration modes of the measuring section to verify the test result of the grouting density; further determine the specific location of the grouting defect by narrowing the measuring section range;

[0039] Step S3: After the grouting density test of the grouting sleeve is completed, if the density is qualified, the quality of the sleeve is qualified and it is put into use. At this time, the intelligent sensor pasted on the surface of the sleeve can perform long-term damage monitoring of the grouting sleeve; the real-time axial strain of the grouting sleeve is obtained by calculating the resistance change of the voltage electrode. If the resistance suddenly changes and the resistance changes sharply, it is judged that the grouting sleeve is damaged; the specific location where the grouting sleeve is damaged is further determined by narrowing the measuring section.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve of the present invention can realize non-destructive detection, maintain the integrity and safety of the structure, and provide real-time monitoring function to quickly obtain monitoring data; utilizing the intelligent characteristics of carbon fiber, the sensor has high sensitivity and can sensitively detect internal defects and unevenness of the structure; utilizing the unique material advantages of carbon fiber, the sensor has strong corrosion resistance and fatigue resistance, good environmental adaptability, no interference with the structure and environment, and is suitable for various complex construction environments; the sensor is simple in design, easy to operate, and does not require additional monitoring equipment, and has high economy. By analyzing the strain mode vibration type, the sensor can comprehensively evaluate the grouting density, and combine the comparison of multi-order strain mode vibration types to accurately locate and verify grouting defects; by analyzing the resistance change of the sensor, the long-term performance and damage of the sleeve grouting can be self-perceived and self-monitored.

[0042] Note that the description of these effects does not prevent the existence of other effects. One embodiment of the present invention does not necessarily have all of the above effects. Effects other than the above can be clearly seen and extracted from the description of the specification, drawings, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of an intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve according to an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of sensor electrode assembly according to one embodiment of the present invention;

[0045] Figure 3 FIG. 1 is a schematic diagram of sensor electrode connection during detection according to an embodiment of the present invention.

[0046] The reference numerals are as follows:

[0047] 1-carbon fiber strip, 2-tinned copper wire, 3-conductive silver glue, 4-epoxy resin; 5-current electrode; 6-voltage electrode; 7-grouting sleeve; 8-resistance tester. DETAILED DESCRIPTION

[0048] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, 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 invention, and should not be construed as limiting the present invention.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "front", "back", "left", "right", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] The intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve of the present invention is mainly used to monitor the construction quality and long-term performance of the grouting sleeve, and comprises a continuous unidirectional carbon fiber strip, a pair of end electrodes and a plurality of surface electrodes, which are fixedly connected by a conductive material and encapsulated with epoxy resin; the end electrodes are symmetrically arranged at the ends of both ends of the carbon fiber strip, and the surface electrodes are equidistantly arranged on the surface of the carbon fiber strip in parallel. The end electrodes can be used to energize and detect the data of an entire measuring section of the end of the carbon fiber strip, and the surface electrodes can only be used to test data.

[0052] Figure 1 The figure shows a preferred embodiment of the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve, wherein the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve comprises a unidirectional carbon fiber strip 1, a current electrode 5 and a voltage electrode 6;

[0053] Both ends of the carbon fiber strip 1 are provided with current electrodes 5 as end electrodes, and the surface of the carbon fiber strip 1 is provided with a plurality of voltage electrodes 6 as surface electrodes; the current electrode 5 and the voltage electrode 6 are fixed with conductive materials and encapsulated with epoxy resin 4.

[0054] The current electrode 5 and the voltage electrode 6 are made of conductive wires.

[0055] Preferably, the wire is a tinned copper wire 2.

[0056] The conductive material is conductive silver paste 3.

[0057] The current electrode 5 and the voltage electrode 6 are formed by bonding the tinned copper wire 2 and the carbon fiber strip 1 through the conductive silver glue 3 to form a conductive path; the part where the tinned copper wire 2 is cured with epoxy resin 4 is each electrode, and the part where the epoxy resin 4 is not coated is the measuring point corresponding to each electrode; the end electrode of the sensor can be used as both a current electrode and a voltage electrode

[0058] Each end electrode is connected to a wire as a current electrode, and the surface electrode is connected to a wire as a voltage electrode test resistance. The number and arrangement spacing of the surface electrodes are determined according to the length and width of the carbon fiber strip.

[0059] The current electrode 5 at one end of the carbon fiber strip 1 is made of a tinned copper wire 2 bonded to one end of the carbon fiber strip 1 by conductive silver glue 3. The tinned copper wire 2 is arranged on the carbon fiber strip 1 in a winding manner and is pasted with conductive silver glue 3 to form a number of equidistantly arranged voltage electrodes 6 until it is wound to the other end of the carbon fiber strip 1. The tinned copper wire 2 and the carbon fiber strip 1 are bonded with conductive silver glue 3 to form the current electrode 5 at the other end of the carbon fiber strip 1.

[0060] Figure 2 This is a schematic diagram of sensor electrode assembly. Excess resin and dust are cleaned at the electrode arrangement of the carbon fiber strip 1. The tinned copper wire 2 and the carbon fiber strip 1 are bonded with conductive silver glue 3 to ensure the formation of a conductive path. After the conductive silver glue 3 is cured, the electrode can be encapsulated with epoxy resin 4 to protect the electrode.

[0061] Figure 3 It is a schematic diagram of the connection of sensor measuring points during detection. The grouting sleeve 7 whose density is to be detected is connected to the resistance tester 8 through the tinned copper wire 2.

[0062] The length of the carbon fiber strip 1 can be selected according to the actual engineering situation, but the width-to-length ratio must be 0.05-0.2, the thickness must be 1-1.2 mm, and the sensitivity and linearity must be good. Preferably, the axial compression along the carbon fiber strip 1 is tested, the width-to-length ratio is 0.125, the thickness is 1.2 mm, the sensitivity can reach 158.76, and the linearity R 2 Reached 0.97842.

[0063] During the sensor preparation process, the two ends of the carbon fiber strip 1 and the surface electrode arrangement are polished with sandpaper, and then wiped with acetone to remove dust and resin on the surface; a tinned copper wire 2 is bonded to one end of the carbon fiber strip 1 through a conductive silver glue 3 to form a current electrode 5, and the tinned copper wire 2 is arranged on the carbon fiber strip 1 in a winding manner and pasted with the conductive silver glue 3 to form a voltage electrode 6, until it is wound to the other end of the carbon fiber strip 1, and the tinned copper wire 2 and the end are bonded with the conductive silver glue 3 to form a current electrode 5; after the conductive silver glue 3 is cured, the tinned copper wire 2 wrapped on the surface of the carbon fiber strip 1 is encapsulated with epoxy resin 4, and after the epoxy resin 4 is cured, the sensor is prepared, and the part where the tinned copper wire 2 is cured with the epoxy resin 4 is each electrode, and the part where the epoxy resin 4 is not cured is each measuring point.

[0064] Specifically, a method for preparing the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve comprises the following steps:

[0065] Step S1: Use sandpaper to polish the two ends of the carbon fiber strip 1 and the surface electrode arrangement location, and then use acetone to wipe it after polishing to remove dust and resin on the surface;

[0066] Step S2: a tinned copper wire 2 is pasted to one end of the carbon fiber strip 1 and bonded with a conductive silver glue 3 to form a current electrode 5. After one end is fixed, the tinned copper wire 2 is equidistantly wound on the surface of the carbon fiber strip 1 in a spiral form and bonded with the conductive silver glue 3 to form a plurality of voltage electrodes 6. The tinned copper wire 2 and the carbon fiber strip 1 are bonded with the conductive silver glue 3 to form a current electrode 5 at the other end of the carbon fiber strip 1.

[0067] Step S3: After the conductive silver glue 3 is cured, the epoxy resin 4 is used to encapsulate the conductive silver glue 3 . After the epoxy resin 4 is cured, the smart sensor is prepared.

[0068] When the intelligent sensor of this embodiment is used to detect the density of grouting sleeve, for example, the sensor is arranged around the surface of the grouting sleeve 7 along the angle θ; the position where the sensor is arranged is polished with sandpaper, and then wiped with acetone to remove surface stains; a thin layer of epoxy resin 4 is brushed on the place, and the prepared sensor is pasted on the thin layer of epoxy resin 4. After the epoxy resin 4 is cured, it can be used to detect the density of sleeve grouting; then the current electrode 5 of the sensor is connected to the driving end of the resistance tester 8 through the tinned copper wire 2, and the other two wires are connected to the voltage electrode 6 to be tested and the detection end of the resistance tester 8, and the resistance tester 8 is turned on to start recording the real-time resistance of the measuring section, and the initial resistance R of each measuring point is obtained by testing. i Use a hammer to hammer the grouting sleeve 7 to obtain the resistance change ΔR of each measuring section i ; The first three strain modes of each measuring section are obtained by analysis and compared with the standard strain mode. If the strain mode has a sudden change, it means that the sleeve grouting within the measuring section is not dense enough and there is a defect. The resistance change ΔR of other surface voltage electrodes 6 can be further tested. i Determine the specific location of the grouting defect; by measuring the resistance change ΔR of each voltage electrode 6 i , the axial strain of the grouting sleeve 7 can be monitored over a period of time. If the resistance change ΔR i A sharp increase indicates that the grouting sleeve 7 is damaged, which can be further verified by testing the resistance change ΔR of other voltage electrodes 6. i Determine exactly where the injury occurred.

[0069] Specifically, a monitoring method based on the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve comprises the following steps:

[0070] Define the angle between the smart sensor and the axial direction of the grouting sleeve 7 as θ, and arrange the smart sensor around the grouting sleeve 7 along the angle θ; use sandpaper to polish the position where the smart sensor is arranged, and then wipe it with acetone to remove surface stains; apply a thin layer of epoxy resin on the position where the smart sensor is arranged, and stick the smart sensor on the thin layer of epoxy resin; after the epoxy resin is cured, it can be used to detect the grouting density of the grouting sleeve 7, that is, the construction quality of the grouting sleeve.

[0071] The monitoring method of the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve also includes the following steps:

[0072] The first three standard strain modal vibration modes of the grouting sleeve 7 are obtained by hammering the grouting sleeve 7 with qualified construction quality; the strain modal vibration modes obtained by the resistance change of the voltage electrode 6 are compared with the standard strain modal vibration modes. Any order of strain modal vibration modes can reflect the construction quality of the grouting sleeve, and the other two orders of strain modal vibration modes can be used for verification; the damage condition of the grouting sleeve 7 is obtained by the resistance change of each voltage electrode 6 to monitor the long-term performance of the grouting sleeve 7.

[0073] In a specific embodiment of the present invention, the monitoring method of the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve comprises the following steps:

[0074] Step S1): Arrange the smart sensor on the grouting sleeve 7 with good grouting density; then connect the current electrode 5 of the smart sensor to the driving end of the resistance tester 8 through a wire, take another two wires to connect the voltage electrode 6 to be tested and the detection end of the resistance tester 8, turn on the resistance tester 8 to start recording the real-time resistance of the smart sensor; test and obtain the initial resistance R of each measuring section i , i = 1, 2, 3 ... n, n is a positive integer; hammer the grouting sleeve 7 with a hammer to obtain the resistance change ΔR of each measuring section i , i = 1, 2, 3 ... n, n is a positive integer; the axial strain of the grouting sleeve 7 is calculated using the following formula:

[0075]

[0076] in:

[0077] ε is the axial strain of the grouting sleeve;

[0078] θ is the angle between the smart sensor and the axial direction of the grouting sleeve;

[0079] μ is the Poisson’s ratio of the smart sensor, obtained by fitting the test data;

[0080] ΔR i is the resistance change of the smart sensor;

[0081] K θ is the strain sensitivity coefficient when the angle between the intelligent sensor and the axial direction of the grouting sleeve is θ, which is obtained by fitting the test data;

[0082] R i is the initial resistance of the smart sensor;

[0083] Due to the piezoresistive properties of carbon fiber, its resistance will change when strain occurs. Therefore, when the grouting sleeve structure undergoes the rth order main vibration, the distribution of the resistance change of each voltage electrode of the sensor will also show a corresponding inherent change law. By analyzing the resistance change of each measuring section, the strain modal vibration type of the grouting sleeve can be determined. The resistance change ΔR i The first three strain modal vibration modes of the grouting sleeve with good density are obtained by fitting and normalization. This strain modal vibration mode is the standard strain modal vibration mode.

[0084] Step S2): Arrange the intelligent sensor on the grouting sleeve of the grouting density to be tested, repeat the operation in step S1) to obtain the first three-order strain modal vibration modes of the grouting sleeve to be tested, and compare the first three-order strain modal vibration modes of the grouting sleeve to be tested with the standard strain modal vibration modes; since the mass and stiffness and other structural physical parameters of the defective part of the sleeve grouting are different from those of the dense part, its natural frequency will change, which is reflected by the strain modal vibration mode; compare the first-order strain modal vibration mode of each measuring section, if there is a sudden change in the comparison between the measuring section and the standard strain modal vibration mode, it means that there is a defect in the grouting within this test range; compare the second-order and third-order strain modal vibration modes of the measuring section to verify the test result of the grouting density; further determine the specific location of the grouting defect by narrowing the measuring section range;

[0085] Step S3): After the grouting density test of the grouting sleeve is completed, if the density is qualified, the construction quality of the sleeve is qualified and can be put into use. At this time, the intelligent sensor pasted on the surface of the sleeve can perform long-term damage monitoring of the grouting sleeve; the real-time axial strain of the grouting sleeve is obtained by calculating the resistance change of the voltage electrode 6. If the resistance suddenly changes and the resistance changes sharply, it is judged that the grouting sleeve is damaged; the specific location where the grouting sleeve is damaged is further determined by narrowing the measuring section range.

[0086] The intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve of the present invention comprises a carbon fiber strip 1 and an electrode; the electrode arrangement position of the carbon fiber strip 1 is polished with sandpaper, and the tinned copper wire 2 is spirally wound on the carbon fiber strip 1 through a conductive silver glue 3 to form an electrode. After the conductive silver glue 3 is cured, it is encapsulated with an epoxy resin 4; the sensor is arranged on the surface of the grouting sleeve 7; the resistance change measured by the electrode reflects the strain mode vibration type of the grouting sleeve on the one hand, and the construction quality of the grouting sleeve is detected by comparing the strain mode vibration type; the resistance change also reflects the damage of the grouting sleeve, and the long-term performance of the grouting sleeve is monitored accordingly. The sensor is simple to prepare, easy to operate, and highly economical. It can simultaneously realize the monitoring of the construction quality and long-term performance of the grouting sleeve and determine its damage location, and can be widely used in prefabricated buildings using grouting sleeves.

[0087] The present invention can realize non-destructive detection, maintain the integrity and safety of the structure, and provide real-time self-sensing and damage self-monitoring functions of the sleeve structure state, and quickly obtain monitoring data; using the unique material advantages of carbon fiber, the sensor is corrosion-resistant and fatigue-resistant, and the monitoring results are highly sensitive, and has good self-sensing characteristics for structural defects and unevenness, and can accurately locate grouting defects caused by construction, and monitor the structural damage state in real time. In addition, the intelligent sensor has strong environmental adaptability, no interference with the structure and environment, and is suitable for various complex construction environments; the sensor is simple in design, easy to operate, does not require additional monitoring equipment, and has high economic efficiency.

[0088] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0089] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An intelligent sensor for monitoring the quality and long-term performance of grouting sleeves, characterized in that: It comprises a carbon fiber strip (1), a current electrode (5) and a voltage electrode (6); Both ends of the carbon fiber strip (1) are provided with current electrodes (5) as end electrodes, and the surface of the carbon fiber strip (1) is provided with a plurality of voltage electrodes (6) as surface electrodes; the current electrodes (5) and the voltage electrodes (6) are both fixed with conductive materials and encapsulated with epoxy resin (4).

2. The intelligent sensor for monitoring the quality and long-term performance of grouting sleeves according to claim 1 is characterized in that: The current electrode (5) and the voltage electrode (6) are made of conductive wires.

3. The intelligent sensor for monitoring the quality and long-term performance of grouting sleeves according to claim 2 is characterized in that: The wire is a tinned copper wire (2).

4. The intelligent sensor for monitoring the quality and long-term performance of grouting sleeves according to claim 3 is characterized in that: The conductive material is conductive silver paste (3).

5. The intelligent sensor for monitoring the quality and long-term performance of grouting sleeves according to claim 4 is characterized in that: The current electrode (5) at one end of the carbon fiber strip (1) is made by bonding a tinned copper wire (2) to one end of the carbon fiber strip (1) via a conductive silver glue (3). The tinned copper wire (2) is arranged on the carbon fiber strip (1) in a winding manner and pasted with a conductive silver glue (3) to form a plurality of equally spaced voltage electrodes (6), until it is wound to the other end of the carbon fiber strip (1). The tinned copper wire (2) and the carbon fiber strip (1) are bonded with the conductive silver glue (3) to form the current electrode (5) at the other end of the carbon fiber strip (1).

6. The intelligent sensor for monitoring the quality and long-term performance of grouting sleeves according to claim 1, characterized in that: The carbon fiber strip (1) has a width-to-length ratio of 0.05-0.2 and a thickness of 1-1.2 mm.

7. A method for preparing an intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1: using sandpaper to polish the two ends of the carbon fiber strip (1) and the surface where the electrodes are arranged, and then wiping with acetone to remove dust and resin on the surface; Step S2: a tinned copper wire (2) is adhered to one end of the carbon fiber strip (1) and bonded with a conductive silver glue (3) to form a current electrode (5); after one end is fixed, the tinned copper wire (2) is equally wound around the surface of the carbon fiber strip (1) in a spiral form and bonded with a conductive silver glue (3) to form a plurality of voltage electrodes (6); the tinned copper wire (2) and the carbon fiber strip (1) are bonded with the conductive silver glue (3) to form a current electrode (5) at the other end of the carbon fiber strip (1); Step S3: After the conductive silver glue (3) is cured, the epoxy resin (4) is used to encapsulate the conductive silver glue (3). After the epoxy resin (4) is cured, the preparation of the smart sensor is completed.

8. A monitoring method for the intelligent sensor for monitoring the quality and long-term performance of a grouting sleeve according to any one of claims 1 to 6, characterized in that: The following steps are involved: The angle between the intelligent sensor and the axial direction of the grouting sleeve (7) is defined as θ, and the intelligent sensor is arranged around the grouting sleeve (7) along the angle θ; a thin layer of epoxy resin is applied to the position where the intelligent sensor is arranged, and the intelligent sensor is pasted on the thin layer of epoxy resin; after the epoxy resin is cured, it can be used to detect the grouting density of the grouting sleeve (7), that is, the construction quality of the grouting sleeve (7).

9. The monitoring method of the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve according to claim 8, characterized in that: The following steps are also included: The first three standard strain modal vibration modes of the grouting sleeve (7) are obtained by hammering a grouting sleeve (7) with qualified construction quality; the strain modal vibration mode obtained by the resistance change of the voltage electrode (6) is compared with the standard strain modal vibration mode, and any order of strain modal vibration mode can reflect the construction quality of the grouting sleeve (7), and the other two orders of strain modal vibration modes can be used for verification; the damage condition of the grouting sleeve (7) is obtained through the resistance change of each voltage electrode (6) to monitor the long-term performance of the grouting sleeve (7).

10. The monitoring method of the intelligent sensor for monitoring the quality and long-term performance of the grouting sleeve according to claim 9, characterized in that: The following steps are involved: Step S1): the intelligent sensor is arranged on a grouting sleeve (7) with good grouting density; then the current electrode (5) of the intelligent sensor is connected to the driving end of the resistance tester (8) through a wire, another wire is taken to connect the voltage electrode (6) to be tested and the detection end of the resistance tester (8), and the resistance tester (8) is turned on to start recording the real-time resistance of the intelligent sensor; the initial resistance R of each measuring section is obtained by testing. i , i = 1, 2, 3 ... n, n is a positive integer; hammer the grouting sleeve (7) with a hammer to obtain the resistance change ΔR of each measuring section i , i = 1, 2, 3 ... n, n is a positive integer; the axial strain of the grouting sleeve (7) is calculated using the following formula: in: ε is the axial strain of the grouting sleeve; θ is the angle between the smart sensor and the axial direction of the grouting sleeve; μ is the Poisson’s ratio of the smart sensor; ΔR i is the resistance change of the smart sensor; K θ is the strain sensitivity coefficient when the angle between the intelligent sensor and the grouting sleeve axis is θ; R i is the initial resistance of the smart sensor; The strain mode vibration type of the grouting sleeve (7) is determined by analyzing the resistance change of each measuring section, and the resistance change ΔR i Fitting and normalization are performed to obtain the first three strain modal vibration modes of the grouting sleeve (7) with good density, and this strain modal vibration mode is the standard strain modal vibration mode; Step S2): Arrange the intelligent sensor on the grouting sleeve (7) whose grouting density is to be tested, repeat the operation in step S1) to obtain the first three strain modal vibration modes of the grouting sleeve (7) to be tested, and compare the first three strain modal vibration modes of the grouting sleeve (7) to be tested with the standard strain modal vibration modes; since the mass, stiffness and other structural physical parameters of the defective part of the sleeve grouting are different from those of the dense part, its natural frequency will change, which is reflected by the strain modal vibration mode; compare the first order strain modal vibration mode of each measuring section, if there is a sudden change in the comparison between the measuring section and the standard strain modal vibration mode, it indicates that there is a defect in the grouting within this test range; compare the second order and third order strain modal vibration modes of the measuring section to verify the test result of the grouting density; determine the specific location of the grouting defect by narrowing the measuring section range; Step S3): After the grouting density of the grouting sleeve (7) is detected, if the density is qualified, the quality of the sleeve is qualified and it is put into use. At this time, the intelligent sensor attached to the surface of the sleeve can perform long-term damage monitoring on the grouting sleeve (7); the real-time axial strain of the grouting sleeve (7) is obtained by calculating the resistance change of the voltage electrode (6); if the resistance suddenly changes and the resistance change increases sharply, it is judged that the grouting sleeve (7) is damaged; and the specific location where the grouting sleeve (7) is damaged is determined by narrowing the measuring section range.

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