Bridge crack detection system

Abstract

The invention belongs to the technical field of bridge crack detection, and particularly relates to a bridge crack detection system, which comprises a data acquisition module used for acquiring bridge surface information; the bridge surface information comprises bridge surface visual information, bridge crack depth information and bridge crack width information; the data analysis module is used for analyzing whether cracks appear on the surface of the bridge or not based on the bridge surface information; when a crack appears on the surface of the bridge, the analysis module calculates the bridge floor crack severity # imgabs2 # based on the width # imgabs0 # of the bridge floor crack and the depth # imgabs1 # of the crack acquired by the data acquisition module; the repair strategy module formulates a bridge floor repair strategy based on the bridge floor crack severity # imgabs3 #; whether cracks appear on the surface of the bridge or not is determined through the data analysis module, and a subsequent repair strategy is determined according to the severity of the cracks, so that different repair strategies are selected according to different cracks, and the workload is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge crack detection, in particular to a bridge crack detection system. Background Art

[0002] Bridges are structures built on rivers, lakes and seas to allow vehicles and pedestrians to pass smoothly. Bridges often deform under the influence of external factors, leading to cracks or even damage. The mechanism of conventional cracks in bridge structures is quite complex, mainly caused by one or several factors, and other factors only play a role in the continued development or aggravation of cracks.

[0003] The prior art also proposes some solutions for bridge crack detection. For example, a patent application with publication number CN116597329A discloses a bridge crack detection system and method based on machine vision, wherein the system includes: a crack detection map acquisition module, used to obtain a preset crack detection map corresponding to the target bridge; an image acquisition route planning module, used to plan an image acquisition route based on the crack detection map; an image acquisition control module, used to control a drone to acquire images of the target bridge based on the image acquisition route. The invention controls the drone to acquire images of the target bridge, and performs crack detection based on the images acquired by the drone based on machine vision, thereby reducing labor costs and avoiding the problem that manual inspections have a certain degree of risk due to the passage of many vehicles on the bridge. The drone can fly to take pictures of places that cannot be reached by staff, such as the bottom of the bridge and bridge piers, thereby improving convenience.

[0004] Although the above technical solution solves the problem of collecting data at places where workers cannot reach, such as the bottom of the bridge and piers, by using drones, after the crack detection is completed, different repair measures need to be selected according to the type of cracks. Since there are many types of cracks and the repair measures are different, it is more troublesome to take repair measures.

[0005] To this end, the present invention provides a bridge crack detection system. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a bridge crack detection system described in the present invention comprises:

[0008] Data acquisition module: The data acquisition module is used to collect bridge surface information;

[0009] The bridge surface information includes: bridge surface visual information, bridge crack depth information, and bridge crack width information;

[0010] Data analysis module: the data analysis module analyzes whether cracks appear on the bridge surface based on the bridge surface information;

[0011] When cracks appear on the bridge surface, the analysis module calculates the width of the cracks based on the data collected by the data acquisition module. and the depth of the cracks Calculate the severity of bridge deck cracks ;

[0012] Repair strategy module: The repair strategy module is based on the severity of bridge deck cracks. Develop a bridge deck rehabilitation strategy.

[0013] It should be noted that the bridge crack width information refers to the crack width on the bridge surface.

[0014] Preferably, the bridge deck crack severity The specific calculation method is:

[0015] ;

[0016] in, is the width of the current crack;

[0017] is the current crack depth.

[0018] Preferably, the data analysis module is also based on the severity of the bridge deck cracks Risk level classification is as follows:

[0019] Pre-set the maximum threshold for bridge deck crack severity ;

[0020] like , then a signal is generated and transmitted to the repair strategy module; if , then the crack expansion rate is calculated based on To determine the risk level; the minimum threshold of the crack expansion rate is pre-set as The maximum threshold of crack expansion rate is ;

[0021] like , a first-level risk signal is generated;

[0022] like , then a secondary risk signal is generated;

[0023] like , a third-level risk signal is generated;

[0024] Set the impact signal to the impact level , ,when =1, it indicates a first-level risk signal. =2, it indicates a secondary risk signal. =3, it indicates a level 3 risk signal.

[0025] Preferably, the crack expansion rate The specific calculation method is:

[0026] in The growth rate of surface cracks;

[0027] is the sum of the crack width and depth at the current time;

[0028] is the sum of the crack width and depth after a single cycle;

[0029] For the cycle time.

[0030] Preferably, the repair strategy module is based on the severity of the bridge deck cracks and the crack growth rate Developing a bridge deck rehabilitation strategy includes;

[0031] Set the repair strategy to the repair level , ,when =1, it indicates the first-level repair signal. =2, it indicates the secondary repair signal. =3, it indicates a level 3 repair signal;

[0032] when =1, a first-level repair signal is generated;

[0033] when =2, a secondary repair signal is generated;

[0034] when =3 and When , a third-level repair signal is generated.

[0035] Preferably, the first-level repair signal includes surface repair measures, waterproof repair measures or reinforcement measures;

[0036] The secondary repair signal includes coating protection measures or grouting repair measures;

[0037] The third-level repair signal includes steel reinforcement measures or chemical injection measures;

[0038] Specifically, the cracks include the following types of cracks: surface cracks, water seepage cracks, and cracks caused by steel bar corrosion. That is, when a first-level repair signal is received, the bridge cracks can be repaired through the following operating methods.

[0039] Preferably, the bridge crack detection system further comprises an evaluation module;

[0040] The evaluation module is used to evaluate whether the vehicle can pass normally when cracks exist;

[0041] Calculate the impact of cracks on bridge stiffness ;

[0042] Calculate bridge deflection under vehicle loads ;

[0043] The maximum threshold of the crack effect on bridge stiffness is preset as and the maximum deflection of the bridge under vehicle load ;

[0044] like , , then it is determined that vehicles of type A travel at a limited speed, and vehicles of type B travel by detour;

[0045] like , , then it is determined that vehicles of type A travel at a limited speed, and vehicles of type B travel by detour;

[0046] like , , then it is determined that Class A and Class B vehicles take a detour.

[0047] Preferably, the specific calculation method of the impact value of cracks on bridge stiffness is:

[0048] ;

[0049] is the bridge stiffness when cracks are present;

[0050] is the stiffness of the bridge when there are no cracks;

[0051] is the crack depth (the distance from the tension zone to the crack);

[0052] is the total height of the section;

[0053] d is an empirical coefficient that depends on the distribution and cross-sectional shape of the cracks;

[0054] Specifically, the initial stiffness of the bridge when there are no cracks The initial stiffness can be calculated using the Euler-Bernoulli beam theory. The initial stiffness here usually refers to the bending stiffness of the beam when subjected to concentrated force or distributed force. The specific calculation method is to first calculate the elastic modulus of the bridge material and the product of the moment of inertia of the bridge section, and then calculate the ratio of the product value to the effective length of the bridge to obtain the initial stiffness of the bridge.

[0055] Preferably, the deflection of the bridge under vehicle load is calculated as follows:

[0056]

[0057] in, is the deflection of the bridge under vehicle load ;

[0058] q is the vehicle load ( );

[0059] L is the span of the bridge ;

[0060] P is the support stiffness ( );

[0061] E is the elastic modulus of the bridge material ;

[0062] I is the moment of inertia of the area .

[0063] Preferably, the data acquisition module collects bridge surface information in the following manner:

[0064] Step 1: Photograph the bridge and collect image information of the bridge surface through visual inspection technology; Visual inspection technology, especially machine vision-based systems, has played an important role in bridge crack detection; these systems collect images of the bridge surface using high-resolution cameras, paying attention to the distribution, shape and width of cracks;

[0065] Step 2: Use non-destructive testing ultrasonic and magnetic particle testing technology to measure the width and depth of the crack.

[0066] The beneficial effects of the present invention are as follows:

[0067] The bridge crack detection system described in the present invention determines the risk level when cracks appear on the bridge by calculating the severity of the bridge cracks and the expansion rate of the bridge cracks, and determines different repair measures according to different risk levels. It is more convenient to use, and can take specific repair measures for specific cracks and reasonably allocate repair resources. At the same time, it can also determine whether vehicles can pass normally based on the presence of cracks, thereby improving the service life and convenience of the bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The present invention will be further described below in conjunction with the accompanying drawings.

[0069] Figure 1 It is a system diagram of the present invention. DETAILED DESCRIPTION

[0070] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0071] Bridges are buildings built on rivers, lakes, and seas to allow vehicles and pedestrians to pass smoothly. Bridges often deform under the influence of external factors, leading to cracks or even damage. The mechanism of conventional cracks in bridge structures is quite complex, mainly caused by one or several factors, and other factors only play a role in the continued development or aggravation of cracks. After the crack detection is completed, the existing technology needs to select different repair measures according to the type of cracks. Since there are many types of cracks and the repair measures are also different, it is more troublesome to take repair measures;

[0072] like Figure 1 As shown, a bridge crack detection system according to an embodiment of the present invention includes: a data acquisition module, a data analysis module and a repair strategy module;

[0073] Data acquisition module: The data acquisition module is used to collect bridge surface information;

[0074] The bridge surface information includes: bridge surface visual information, bridge crack depth information, and bridge crack width information;

[0075] Data analysis module: the data analysis module analyzes whether cracks appear on the bridge surface based on the bridge surface information;

[0076] When cracks appear on the bridge surface, the analysis module calculates the width of the cracks based on the data collected by the data acquisition module. and the depth of the cracks Calculate the severity of bridge deck cracks ;

[0077] Repair strategy module: The repair strategy module is based on the severity of bridge deck cracks. Develop a bridge deck rehabilitation strategy.

[0078] It should be noted that the bridge crack width information refers to the crack width at the bridge surface;

[0079] Specifically, bridge cracks generally include surface cracks and deep cracks: Surface cracks are generally mesh cracks: usually occur on beams of various spans, these cracks are small, mostly surface cracks caused by concrete shrinkage, with a width of about 0.03-0.55mm; Deep cracks are also called through cracks, generally vertical cracks on the web: this is one of the common cracks in reinforced concrete beams, especially when the span is greater than 12m, the cracks are mostly located in the thin web, and the crack width is larger near the half-height line of the beam, generally 0.15-0.3mm; Oblique cracks on the web: mostly appear on both sides of the mid-span, the farther away from the mid-span, the greater the inclination angle, usually caused by design defects or the main tensile stress exceeding the concrete load capacity;

[0080] Cracks on the upper part of the beam end: The uneven settlement of the pier may cause the local support pressure at the beam end to increase, thus forming local stress cracks, which crack from bottom to top; Horizontal cracks on the beam side: This type of crack is similar to a layer of cracks in the horizontal direction, which is mostly caused by improper construction, such as layered pouring with too long intervals;

[0081] Cantilever beam shear cracks: Shear cracks appear on the web, and appear to be inclined at an angle of approximately 45 degrees. They generally appear in the area between the support and the inflection point. The causes may be insufficient prestress, overloaded permanent loads, secondary stress or temperature effects, etc. The data analysis module is used to determine whether cracks appear on the bridge surface, and the subsequent repair strategy is determined based on the severity of the cracks, so that different repair strategies can be selected according to different cracks, saving workload;

[0082] Severity of bridge deck cracks The specific calculation method is:

[0083] ;

[0084] in, is the width of the current crack;

[0085] is the depth of the current crack;

[0086] Specifically, by obtaining the width of the bridge deck crack and the depth of the cracks , if the depth and width If the ratio is greater than or equal to 1, it means that the depth and width are equal, or the depth of the crack is large; if the depth and width A ratio much less than 1 indicates that the depth of the bridge Smaller, and wider Large, through the severity of bridge deck cracks Compared with 1, we can preliminarily monitor the specific situation of the cracks, and use the repair strategy module to repair the cracks according to the severity of the bridge deck cracks. to provide remedial measures;

[0087] The width of the bridge deck crack and the depth of the cracks The method of obtaining the crack width is to insert a crack meter into the crack and directly read the crack width; or to use a micrometer to measure the width of a small crack. ;

[0088] Ultrasonic testing, which emits ultrasonic waves into the cracks of a bridge and measures the time it takes for the waves to reflect back, thereby estimating the depth of the cracks. , apply coupling agent on the surface of the bridge, and then use the probe to transmit and receive ultrasonic waves. The sound waves will be reflected when they encounter cracks or interfaces between different materials. The location and size of the defects are determined by analyzing the time and intensity of the reflected waves.

[0089] The data analysis module is also based on the severity of the bridge deck cracks Risk level classification is as follows:

[0090] Pre-set the maximum threshold for bridge deck crack severity ; The highest threshold of bridge deck crack severity It is obtained by staff based on historical experience;

[0091] like , then a signal is generated and transmitted to the repair strategy module; if , then the crack expansion rate is calculated based on To determine the risk level; the minimum threshold of the crack expansion rate is pre-set as The maximum threshold of crack expansion rate is ; The minimum threshold of crack expansion rate is The maximum threshold of crack expansion rate is It is obtained by the staff according to the specific structure of the bridge;

[0092] like , a first-level risk signal is generated;

[0093] like , then a secondary risk signal is generated;

[0094] like , a third-level risk signal is generated;

[0095] Set the impact signal to the impact level , ,when =1, it indicates a first-level risk signal. =2, it indicates a secondary risk signal. =3, it indicates a level 3 risk signal;

[0096] Specifically, since surface cracks are usually limited to the surface of the bridge, they may be caused by drying shrinkage, temperature changes, surface erosion, etc., and generally do not penetrate the entire cross-section, and have little impact on the structural strength. Therefore, the solution to this problem is relatively simple; however, when surface cracks appear, they also need to be regularly inspected. When the expansion rate of the bridge surface cracks in a cycle is When the expansion rate of cracks on the bridge surface is low, this information can be classified as a first-level risk, which means the risk is minimal and only requires simple repair measures. When the expansion rate is between the two thresholds, such information can be classified as a secondary risk, that is, the risk is medium. At this time, the staff needs to strengthen the repair measures to prevent the surface cracks from gradually evolving into deep cracks. When the expansion rate of the bridge surface cracks is When it is greater than the maximum threshold of the expansion rate, staff are required to deal with the cause of the cracks in a timely manner.

[0097] The crack growth rate The specific calculation method is:

[0098] in The growth rate of surface cracks;

[0099] is the sum of the crack width and depth at the current time;

[0100] is the sum of the crack width and depth after a single cycle;

[0101] is the cycle time;

[0102] Specifically, when the data analysis module detects cracks on the bridge surface, the staff will first record the sum of the crack width and depth. , record the sum of the crack width and depth within the predetermined period , where the predetermined period can be one week to record the length and width of the same crack, and the sum of the width and depth of the next crack The sum of the width and depth of the crack recorded for the first time By performing a difference calculation and performing a ratio calculation on the result of the difference for this cycle, the crack expansion rate in the current cycle can be obtained. ;

[0103] Analyze the results of the crack growth rate. If the growth rate If the value is large, it indicates that the crack expands rapidly, and further evaluation is needed to determine the depth of the crack and the width of the surface crack, and to develop appropriate repair strategies.

[0104] It is further necessary to observe the distribution of cracks on the bridge structure and pay attention to whether the cracks are concentrated in specific areas, such as joints, near supports or parts with greater stress. The shape of the cracks can provide clues about the cause of the cracks. Straight cracks may indicate that the structure is stretched, while jagged or irregular cracks may be related to material fatigue or uneven stress. The expansion rate of surface cracks obtained by calculation can facilitate the subsequent treatment of bridge surface cracks.

[0105] The repair strategy module is based on the severity of bridge deck cracks and the crack growth rate Developing a bridge deck rehabilitation strategy includes;

[0106] Set the repair strategy to the repair level , ,when =1, it indicates the first-level repair signal. =2, it indicates the secondary repair signal. =3, it indicates a level 3 repair signal;

[0107] when =1, a first-level repair signal is generated;

[0108] when =2, a secondary repair signal is generated;

[0109] when =3 and When , a third-level repair signal is generated;

[0110] Specifically, when cracks appear on the bridge surface, that is, when a first-level risk signal appears, the surface cracks have little impact on the subsequent development, and a first-level repair signal is generated. The first-level repair signal includes repairing with caulking agents, waterproofing and sealing with flexible materials, excavation and patching, replacing the original concrete protective layer, etc.

[0111] When the secondary risk signal appears, the impact of the surface cracks on the subsequent situation is moderate, and a secondary repair signal is generated. The secondary repair signal includes electrochemical desalination or cathodic protection, plugging cracks, using protective coatings and other methods to slow down the reaction, and pouring high-strength grouting materials such as cement-based grouting or chemical grouting to fill the cracks and restore the integrity of the structure.

[0112] When a level 3 risk signal appears, the surface cracks have a greater impact on the current and subsequent situations, and a level 3 repair signal is generated. The level 3 repair signal includes local excision and replacement, using new concrete or other materials for repair; using external reinforcement technology, such as carbon fiber reinforcement, steel plate reinforcement or prestressed reinforcement, etc.

[0113] The first-level repair signal includes surface repair measures, waterproof repair measures or reinforcement measures;

[0114] The secondary repair signal includes coating protection measures or grouting repair measures;

[0115] The third-level repair signal includes steel reinforcement measures or chemical injection measures;

[0116] Specifically, cracks include the following types of cracks: surface cracks, water seepage cracks, and cracks caused by steel bar corrosion. That is, when a first-level repair signal is received, the bridge cracks can be repaired through the following operation methods;

[0117] For surface repair measures, caulking agents can be used for repair. Caulking agents can fill cracks and have a certain degree of adhesion, effectively preventing cracks from further expanding;

[0118] Waterproof repair measures are aimed at water seepage cracks and active cracks. For water seepage cracks and active cracks, flexible materials can be used for waterproofing and sealing. Reinforcement measures are aimed at some dead seams, and rigid materials can be used for waterproofing and reinforcement.

[0119] When a secondary repair signal is received, it is solved through coating protection measures or grouting repair measures;

[0120] Coating protection measures include cracks caused by steel bar corrosion. If it is carbonization corrosion, the original concrete protective layer can be replaced by the digging method, and protective materials can be applied to the steel bars. If it is chloride ion corrosion, the source of chloride ions needs to be analyzed and corresponding treatment measures need to be taken, such as electrochemical desalination or cathodic protection. Grouting repair measures include pouring concrete into deep cracks.

[0121] When a level 3 repair signal is received, the problem is solved by reinforcing the steel bars or taking chemical grouting measures. For deeper cracks, high-strength grouting materials such as cement-based grouting or chemical grouting need to be injected to fill the cracks and restore the integrity of the structure. If the cracks are caused by steel bar corrosion, the damaged steel bars need to be replaced or reinforced, and ensure that the new steel bars have sufficient protective layer thickness. Alternatively, external reinforcement techniques such as carbon fiber reinforcement, steel plate reinforcement or prestressed reinforcement can be used to improve the bearing capacity and durability of the bridge.

[0122] The bridge crack detection system also includes an evaluation module;

[0123] The evaluation module is used to evaluate whether the vehicle can pass normally when cracks exist;

[0124] Calculate the impact of cracks on bridge stiffness ;

[0125] Calculate bridge deflection under vehicle loads ;

[0126] The maximum threshold of the crack effect on bridge stiffness is preset as and the maximum deflection of the bridge under vehicle load ; The highest threshold of crack influence on bridge stiffness is and the maximum deflection of the bridge under vehicle load It is obtained by the staff according to the specific structure of the bridge;

[0127] like , , then it is determined that vehicles of type A travel at a limited speed, and vehicles of type B travel by detour;

[0128] like , , then it is determined that vehicles of type A travel at a limited speed, and vehicles of type B travel by detour;

[0129] like , , then it is determined that vehicles of category A and category B should take a detour;

[0130] It should be noted that vehicles are divided into Class A vehicles and Class B vehicles. In the specific implementation process, Class A vehicles can be ordinary cars and four-axle trucks with a tonnage of less than 31 tons; Class B vehicles can be four-axle trucks with a tonnage of more than 31 tons, and Class B vehicles can also be two-axle trucks with a tonnage of more than 18 tons;

[0131] Specifically, bridge stiffness refers to the ability of a bridge to resist deformation under normal conditions, and the deflection of a bridge under vehicle load refers to the vertical displacement or deformation caused by the load when a vehicle passes through. When there is a crack in the bridge, and one of the two changes, the impact value of the current crack on the bridge stiffness is and the deflection of the bridge under vehicle loads One of the items is greater than the maximum threshold of bridge stiffness influence and the maximum deflection of the bridge under vehicle load hour;

[0132] This means that Class A non-overweight vehicles can travel on the bridge at a speed limit of, for example, 50-60 km / h; while Class B overweight vehicles cannot pass through such bridges, and staff are required to monitor the vehicles on the bridge in real time until the bridge is repaired;

[0133] Driving at a limited speed can reduce the vibration caused by vehicles passing by, and also reduce the impact load. Because when vehicles travel at high speed on the bridge surface, especially at the bridge joints or on uneven bridge decks, a large impact load will be generated, which may cause additional pressure on bridges with existing cracks and aggravate the expansion of bridge cracks.

[0134] When both of the two change, the impact of the current crack on the bridge stiffness and the deflection of the bridge under vehicle loads All are greater than the maximum threshold of bridge stiffness influence. and the maximum deflection of the bridge under vehicle load When the cracks appear, it means that the normal driving of the bridge has been affected. At this time, all vehicles should be stopped until the bridge is repaired.

[0135] The specific calculation method of the impact of cracks on bridge stiffness is:

[0136] ;

[0137] is the bridge stiffness when cracks are present;

[0138] is the stiffness of the bridge when there are no cracks;

[0139] is the crack depth (the distance from the tension zone to the crack);

[0140] is the total height of the section;

[0141] d is an empirical coefficient that depends on the distribution and cross-sectional shape of the cracks;

[0142] Specifically, the initial stiffness of the bridge when there are no cracks The initial stiffness can be calculated by the Euler-Bernoulli beam theory. The initial stiffness here usually refers to the bending stiffness of the beam when it is subjected to concentrated force or distributed force. The specific calculation method is to first calculate the elastic modulus of the bridge material and the moment of inertia product of the bridge section, and then calculate the ratio of the product value to the effective length of the bridge to obtain the initial stiffness of the bridge.

[0143] When the initial stiffness of the bridge is known, the stiffness of the bridge when cracks exist , first introduce the crack damage ratio , and then the initial stiffness of the bridge without cracks and Multiplying together gives , d is an empirical coefficient, which depends on the distribution and cross-sectional shape of the cracks and has a range of ,if , indicating no loss of stiffness, , it means that the stiffness is completely lost. When determining d, it is necessary to consider the characteristics of the crack, such as whether the crack penetrates the cross section, the width of the crack, etc.;

[0144] By calculating the bridge stiffness when cracks exist, it reflects the bridge's ability to resist deformation within the elastic range. When the load is removed, the structure can return to its original shape. Sufficient stiffness can ensure that the bridge has sufficient safety performance within its design service life. When an abnormality occurs, the vehicle's movement needs to be controlled. For example, larger trucks should stop running and move onto the bridge.

[0145] The deflection of the bridge under vehicle load is calculated as follows:

[0146]

[0147] in, is the deflection of the bridge under vehicle load ;

[0148] q is the vehicle load ( );

[0149] L is the span of the bridge ;

[0150] P is the support stiffness ( );

[0151] E is the elastic modulus of the bridge material ;

[0152] I is the moment of inertia of the area ;

[0153] Specifically, when calculating the deflection of a bridge under vehicle load, first calculate the vehicle load and the span of the bridge, then calculate the product of the vehicle load and the span of the bridge to the fourth power. According to the Euler Bernoulli beam equation, the differential equation of the beam deflection under load is calculated. When the concentrated load acts on the midpoint of the beam, it is substituted into the equation to obtain Then the vehicle load and the bridge span are multiplied to the fourth power. and By calculating the ratio, we can get the deflection of the bridge under the vehicle load;

[0154] The deflection of a bridge under vehicle load refers to the vertical displacement or deformation caused by the load when the vehicle passes. This deformation is the response of the bridge structure to the load.

[0155] When a vehicle drives onto a bridge, its weight exerts a downward force on the bridge structure, causing elastic or plastic deformation of the bridge material. This deformation is most significant at the midpoint of the bridge span because the load effect here is the greatest. The deflection can take the following forms: energetic deflection: the static vertical displacement of the bridge structure caused by vehicle loads; dynamic deflection: the additional deflection caused by the impact and vibration generated when a vehicle passes through the bridge, which is usually larger than the static deflection; short-term deflection, the deflection generated instantaneously when a vehicle passes, which may partially or fully recover after the vehicle passes; long-term deflection, due to the long-term action of vehicle loads, may cause fatigue or permanent deformation of the bridge material, and this deflection is irreversible.

[0156] The data acquisition module specifically collects bridge surface information in the following manner:

[0157] Step 1: Photograph the bridge and collect image information of the bridge surface through visual inspection technology; Visual inspection technology, especially machine vision-based systems, has played an important role in bridge crack detection; these systems collect images of the bridge surface using high-resolution cameras, paying attention to the distribution, shape and width of cracks;

[0158] Step 2: Use non-destructive testing ultrasonic and magnetic particle testing technology to measure the width and depth of the cracks. Ensure the comprehensiveness of the evaluation results; ultrasonic testing uses high-frequency sound waves to penetrate materials and detect internal defects based on the propagation time, attenuation and reflection characteristics of sound waves in the material. It is suitable for the inspection of concrete and metal materials and can detect cracks, voids and unevenness. Magnetic particle testing is mainly used for ferromagnetic materials. It detects surface or near-surface cracks and other defects by applying a magnetic field and sprinkling magnetic particles on the surface of the material. The presence of cracks will interfere with the magnetic field, causing the magnetic particles to accumulate at the defects and form visible indications.

[0159] By calculating the severity of bridge cracks and the expansion rate of bridge cracks, the risk level of bridge cracks can be determined, and different repair measures can be determined according to different risk levels. It is more convenient to use, and specific repair measures can be taken for specific cracks, and repair resources can be reasonably allocated. At the same time, it can also determine whether vehicles can pass normally based on the existence of cracks, thereby improving the service life of the bridge and the convenience of the bridge itself.

[0160] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A bridge crack detection system, characterized in that: include: Data acquisition module: The data acquisition module is used to collect bridge surface information; The bridge surface information includes: bridge surface visual information, bridge crack depth information, and bridge crack width information; Data analysis module: the data analysis module analyzes whether cracks appear on the bridge surface based on the bridge surface information; When cracks appear on the bridge surface, the analysis module calculates the width of the cracks based on the data collected by the data acquisition module. and the depth of the cracks Calculate the severity of bridge deck cracks ; Repair strategy module: The repair strategy module is based on the severity of bridge deck cracks. Develop a bridge deck rehabilitation strategy.

2. A bridge crack detection system according to claim 1, characterized in that: Severity of bridge deck cracks The specific calculation method is: ； in, is the width of the current crack; is the current crack depth.

3. A bridge crack detection system according to claim 1, characterized in that: The data analysis module is also based on the severity of the bridge deck cracks Risk level classification is as follows: Pre-set the maximum threshold of bridge deck crack severity ; like , then a signal is generated and transmitted to the repair strategy module; like , then the crack expansion rate is calculated based on To determine the level of risk; The minimum threshold of crack expansion rate is preset as The maximum threshold of crack expansion rate is ; like , a first-level risk signal is generated; like , then a secondary risk signal is generated; like , a third-level risk signal is generated; Set the impact signal to the impact level , ,when =1, it indicates a first-level risk signal. =2, it indicates a secondary risk signal. =3, it indicates a level 3 risk signal.

4. A bridge crack detection system according to claim 3, characterized in that: The crack growth rate The specific calculation method is: in The growth rate of surface cracks; is the sum of the crack width and depth at the current time; is the sum of the crack width and depth after a single cycle; For the cycle time.

5. A bridge crack detection system according to claim 4, characterized in that: The repair strategy module is based on the severity of bridge deck cracks and the crack growth rate Developing a bridge deck rehabilitation strategy includes: Set the repair strategy to the repair level , ,when =1, it indicates the first-level repair signal. =2, it indicates the secondary repair signal. =3, it indicates a level 3 repair signal; when =1, a first-level repair signal is generated; when =2, a secondary repair signal is generated; when =3 and When , a third-level repair signal is generated.

6. A bridge crack detection system according to claim 5, characterized in that: The first-level repair signal includes surface repair measures, waterproof repair measures or reinforcement measures; The secondary repair signal includes coating protection measures or grouting repair measures; The third-level repair signal includes steel reinforcement measures or chemical injection measures.

7. A bridge crack detection system according to claim 1, characterized in that: The bridge crack detection system also includes an evaluation module; The evaluation module is used to evaluate whether the vehicle can pass normally when cracks exist; Calculate the impact of cracks on bridge stiffness ; Calculate bridge deflection under vehicle loads ; The maximum threshold of the crack effect on bridge stiffness is preset as and the maximum deflection of the bridge under vehicle load ; like , , then it is determined that vehicles of type A travel at a limited speed, and vehicles of type B travel by detour; like , , then it is determined that vehicles of type A travel at a limited speed, and vehicles of type B travel by detour; like , , then it is determined that Class A and Class B vehicles take a detour.

8. A bridge crack detection system according to claim 7, characterized in that: The specific calculation method of the impact value of the crack on the bridge stiffness is: ； is the bridge stiffness when cracks are present; is the stiffness of the bridge when there are no cracks; is the crack depth; is the total height of the section; d is an empirical coefficient that depends on the distribution and cross-sectional shape of the cracks.

9. A bridge crack detection system according to claim 8, characterized in that: The deflection of the bridge under vehicle load is calculated as follows: in, is the deflection of the bridge under vehicle load ; q is the vehicle load ( ); L is the span of the bridge ; P is the support stiffness ( ); E is the elastic modulus of the bridge material ; I is the moment of inertia of the area .

10. A bridge crack detection system according to claim 9, characterized in that: The data acquisition module specifically collects bridge surface information in the following manner: Step 1: Photograph the bridge and collect bridge surface image information using visual inspection technology; Step 2: Use non-destructive testing ultrasonic and magnetic particle testing technology to measure the width and depth of the crack.

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