A bridge pier defect detection system and method based on impact echo method

Abstract

The present invention discloses a pier defect detection system and method based on an impact echo method. The system comprises a mobile structure, the mobile structure comprises a cam tensioning structure, the cam tensioning structure is arranged on a side of a mobile body away from the pier, the detection marking structure is arranged on a side of the mobile body close to the pier, the mobile body, the cam tensioning structure and the detection marking structure are all electrically connected to a control module, the cam tensioning structure comprises a static pulley group and a cam group, and the rotation of the cam is controlled so that the fastening pressure between the mobile structure and the pier can be adjusted; the method comprises the following steps: the mobile structure is installed around the pier through a tensioning belt, the tension of the cam and the tensioning belt is adjusted until it is within the setting range of the controller, the control module controls the movement of the mobile body, the pier is detected, the defective areas are marked, and the detection of the pier is completed; the present invention is applicable to variable-section and constant-section piers, and the mobile structure can operate stably on the pier surface, reducing the subsequent workload.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing of bridges, and in particular to a pier defect detection system and method based on an impact echo method. Background Art

[0002] The middle support structure of a multi-span bridge is called a pier. It is a structure that supports the span structure and transmits the dead load and vehicle live load to the foundation. Therefore, the means and equipment for the detection, maintenance and repair of piers are more important and urgent. Piers are mainly made of reinforced concrete. The main reasons for defects in concrete piers are uneven sunlight, temperature changes caused by the four seasons, and external loads.

[0003] Traditional bridge pier inspection methods include:

[0004] (i) Manual inspection methods such as setting up scaffolding, ladders, and crane baskets. Most bridge inspection methods use manual inspection methods such as setting up scaffolding, crane baskets, and other aerial work platforms. There are many disadvantages to manual inspection methods: manual inspection methods require workers to climb high to conduct inspections, which poses a safety hazard of falling from heights. In addition, in order to ensure the safety of the workers, the inspection process must be slowed down, so the inspection efficiency is low. The manual inspection process is complicated, requires a lot of preliminary preparation work, and has high inspection costs. In addition, manual inspections have poor mobility, and the equipment is bulky, which also hinders the normal passage of roads.

[0005] 2. UAV technology

[0006] With the development of science and technology, drone technology has gradually been applied to the inspection of bridge piers, which reduces the safety risks of workers during operation, improves the inspection efficiency, and has little impact on the normal traffic of the road. However, it is difficult to accurately locate the drone during the inspection process, and it is impossible to achieve a good inspection effect. In addition, drones have strict requirements on the flight environment and are not suitable for carrying a large amount of equipment. At the same time, drone control also requires a certain degree of difficulty, which requires certain control skills of the staff.

[0007] In summary, it is particularly important to provide a device that can not only solve potential safety hazards but also simplify the process of detecting bridge piers.

[0008] The patent document with the authorization announcement number CN215493088U discloses a bridge pier detection device, which uses a climbing mechanism to cooperate with a rotating motor to move the camera when in use, and shoots and detects the surface of the bridge pier, effectively improving the working efficiency of the existing technology. However, the device only detects the surface of the bridge pier and is not applicable to the detection of internal defects of the bridge pier.

[0009] The patent document with the authorization announcement number CN213091558U discloses a highway bridge pier inspection machine. The utility model uses an adjustment bolt to make the support splint cooperate with the movable splint to fix the support splint at the top of the pier, and realizes the displacement adjustment in the horizontal and vertical directions through the horizontally arranged transmission screw and the longitudinally arranged adjustment threaded rod. The ultrasonic detector fixed on the support platform at the end of the adjustment threaded rod realizes the defect detection of the pier. The utility model achieves the purpose of reducing the labor of the inspection personnel and ensuring the inspection accuracy. However, the inspection range of the inspection machine is determined by the size of the horizontally arranged transmission screw and the longitudinally arranged adjustment threaded rod. The size of the inspection machine is relatively large, and the ultrasonic detection used can only realize single-line detection. Summary of the invention

[0010] The purpose of the invention is to provide a pier defect detection system and method based on the impact echo method, which solves the problem of how to achieve flexible detection of cylindrical piers of different sizes and variable-section piers, avoids the addition of guide rails, cantilevers and other mechanisms, reduces detection costs and preliminary preparation work, and reduces the problem of errors in the measurement process.

[0011] The present invention is implemented as follows: a bridge pier defect detection system based on the impact echo method, the detection system comprises a mobile structure and a tension belt connecting a plurality of the mobile structures to form an annular shape,

[0012] The mobile structure includes a mobile body, a control module, a cam tensioning structure, and a detection marking structure. The cam tensioning structure is placed on a side of the mobile body away from the bridge pier, and the detection marking structure is placed on a side of the mobile body close to the bridge pier. The mobile body, the cam tensioning structure, and the detection marking structure are all electrically connected to the control module.

[0013] The cam tensioning structure includes a static pulley group and a cam group, the cam group includes a pressure sensor, a cam support placed on the pressure sensor, a cam placed on the cam support and rotatably connected to the cam support, and a cam motor driving the cam to rotate, the control module controls the rotation of the cam according to the signal of the pressure sensor, and the fastening pressure between the movable structure and the bridge pier is adjustable.

[0014] A further technical solution of the present invention is: the mobile structure is a trolley, and there are several trolleys, the specific number of which is determined according to the size of the pier to be inspected, adjacent trolleys are connected by tension belts, each trolley is individually controlled, and is evenly distributed at intervals of 30 cm to 60 cm along the circumference of the pier cross-section to achieve the best detection effect.

[0015] A further technical solution of the present invention is: the cam parameter design is designed according to the slope of the pier to be inspected and the number of moving structures to meet the requirements of variable-section pier inspection, and the designed cam satisfies: when the cam rotates through the thrust angle, the working surface of the cam rotates from the near rest surface to the far rest surface, the moving structure completes the inspection from the bottom of the pier to the top, and vice versa, the trolley completes the return from the top to the bottom of the pier.

[0016] A further technical solution of the present invention is: the pressure sensor of the present invention feeds back the detected pressure value to the control module, and the control module controls the cam motor to rotate to adjust the tightness of the tension belt according to whether the pressure value is within a preset range. If the pressure value is greater than the preset pressure range, the control module controls the cam motor to rotate so that the cam turns from the distal rest surface to the proximal rest surface to loosen the tension belt; if the pressure value is less than the preset range, the control module controls the cam motor to rotate so that the cam turns from the proximal rest surface to the distal rest surface to tighten the tension belt, thereby ensuring that there is always sufficient friction between the moving structure and the pier surface, thereby ensuring the stable operation of the moving structure.

[0017] A further technical solution of the present invention is that the tightening pressure only needs to ensure that the driving force generated by the movable structure is greater than the friction force exerted on the detection system on the wall surface of the bridge pier.

[0018] A further technical solution of the present invention is that the static pulley assembly includes a static pulley support and a static pulley placed on the static pulley support and rotatably connected to the static pulley support, and the static pulleys on both sides are in the same straight line as the cam.

[0019] A further technical solution of the present invention is that there are two static pulleys, which are symmetrically distributed on both sides of the cam to ensure the stability of the movement of the moving structure.

[0020] A further technical solution of the present invention is that the tensioning belt passes through the bottom of the static pulley, the top of the cam and the bottom of another static pulley in sequence, and the tensioning belt is in tensioning contact with the cam tensioning structure.

[0021] A further technical solution of the present invention is: the detection marking structure includes a signal detection component and a marking component, the signal detection component and the marking component are both electrically connected to the control module, the signal detection component includes a sound sensor, a protective cover placed on the side of the sound sensor close to the pier, a detection motor, a rotatable disk connected to the output end of the detection motor, and a steel ball connected to the outer circumference of the disk through a spring, and the top of the detection motor is connected to the movable body.

[0022] A further technical solution of the present invention is that the sound sensor is 3 cm away from the pier surface.

[0023] A further technical solution of the present invention is that: there are multiple steel balls with different diameters. The disc suspends steel balls of various diameters to detect defects of different depths, and drives the steel balls to move centripetally at a certain rotation speed. The steel balls collide with the pier surface along the tangent direction of the disc and rebound and decelerate, and are dragged by the spring and accelerated again by the disc rotation to enter the next collision.

[0024] A further technical solution of the present invention is: the signal detection module further includes a laser distance measuring sensor, which is placed on the mobile body and electrically connected to the control module. The laser distance measuring sensor feeds back the distance between the mobile structure and the top and bottom of the pier to the control module, and the control module determines whether the distance is less than a preset value. If so, the control module controls the mobile structure to stop running, and if not, the mobile structure continues to run.

[0025] A further technical solution of the present invention is: the marking component includes a spray pot, a nozzle placed at one end of the spray pot, a pull rod connected to the nozzle, and an electromagnet placed on the movable body and electromagnetically attracted to the pull rod, and when the electromagnet is energized, the pull rod presses the nozzle for marking.

[0026] A further technical solution of the present invention is that a permanent magnet is provided at one end of the pull rod connected to the electromagnet.

[0027] A further technical solution of the present invention is: if there is a defect, the control module controls the marking component to energize the electromagnet, and after the electromagnet is energized, it attracts the permanent magnet and pulls the pull rod to press the nozzle to mark the detection part. If there is no defect, the electromagnet is not energized.

[0028] A further technical solution of the present invention is that the marking materials used for marking are not limited to fluorescent agents, inks, etc., provided that they meet the marking function and do not damage the bridge piers.

[0029] A further technical solution of the present invention is that the mobile structure comprises a seat, a traveling assembly disposed on the side of the seat close to the bridge pier, the traveling assembly comprises support members and wheels disposed between the support members and rotatably connected to the support members. The mobile structure is driven by a driving mechanism.

[0030] A further technical solution of the present invention is: the control module includes a control unit and a signal processing unit electrically connected to the control unit.

[0031] A further technical solution of the present invention is: the signal processing unit extracts characteristic parameters of the signal collected by the sound sensor and sends them to the control unit, and the control unit compares the extracted characteristic parameters with a threshold to determine whether there is a defect, and the threshold is determined by an empirical value.

[0032] A further technical solution of the present invention is: the control unit is connected to a local terminal, and the local terminal has a practical function, which is convenient for technicians to process data and manually intervene in subsequent work such as the operation status of a small plan.

[0033] The present invention also provides that the cam parameter design is determined according to the slope of the pier to be detected, and the design is based on the following steps:

[0034] Step 1: Determine the Cam's Working Requirements

[0035] In order to detect cylindrical bridge piers with slopes, after the cam rotates through a certain angle δ0, the push stroke h of the cam push rod should be 5cm to 10cm greater than the difference between the upper and lower cross-sectional radii of the bridge pier;

[0036] Step 2: Determine the cam motion pattern

[0037] Given the pier body slope, it is determined that the cam's push motion law is constant velocity motion. The motion equation is:

[0038] s = hδ / δ0;

[0039] v=hω / δ0;

[0040] a=0;

[0041] In the formula, s is the displacement of the push rod in the horizontal direction, h is the push stroke, δ is the angle of the cam, δ0 is the push stroke angle, v is the speed of the push rod in the horizontal direction, which is determined by the speed of the trolley. ω is the angular velocity of the cam rotation, and a is the acceleration of the push rod;

[0042] The tightening of the tensioning belt is reflected in the change of the circumference. As shown in 1, when the cam rotates a certain angle, the change of the circumference is approximately the change of the hypotenuse of the triangle on the way. In the initial state, the lengths of a, b, and c are known. When the horizontal displacement is s, the change of the circumference of the tensioning belt is:

[0043]

[0044] Where n is the number of mobile structures.

[0045] In actual situations, the change in circumference radius is:

[0046] R`=d` / 2П

[0047] Therefore, the actual deduction process is:

[0048] h s =R`max

[0049] Step 3: Determine the Cam Profile Equation

[0050] For the concentric linear motion pointed push rod disc cam mechanism, the theoretical profile of the cam is:

[0051] x=(r0+s)sinδ

[0052] y=(r0+s)cosδ

[0053] Among them, r0 is the base circle radius, s is the displacement of the push rod, and δ is the angle of rotation of the cam.

[0054] The present invention also provides a bridge pier defect detection method based on the impact echo method. The method is based on the bridge pier defect detection system and comprises the following steps:

[0055] Step 1: Install the mobile structure around the bridge pier through the tensioning belt, with intervals between the mobile structures;

[0056] Step 2: The pressure sensor continuously detects the pressure value applied by the tensioning belt to the mobile structure on the bridge pier and feeds it back to the control module. The control module determines whether the pressure value is within a preset range according to the pressure value, controls the rotation of the cam motor through the control module, and adjusts the tension of the cam and the tensioning belt until it is within the setting range of the controller.

[0057] Step 3: The control module controls the movement of the mobile body, and the detection marking structure monitors the distance between the mobile structure and the top of the pier in real time and feeds back to the control module;

[0058] Step 4: The control module controls the detection and marking structure to detect the bridge pier, transmits the detection signal to the control module for processing, determines whether there are defects, and marks the defective areas;

[0059] Step 5: The control module determines the distance between the mobile structure and the top of the bridge pier according to the signal fed back by the detection marking structure, so as to determine whether the detection of the bridge pier is completed. If yes, proceed to the next step; if not, repeat steps 3 to 5;

[0060] Step 6: After the detection is completed, the control module controls the mobile structure to stop and completes the detection of the bridge pier.

[0061] A further technical solution of the present invention is: in step 1, the movable structure and the tension belt are installed around the bridge pier, the movable structures are evenly distributed along the circumference of the bridge pier wall at intervals of 30 cm to 60 cm, and the movable structures are connected by tension belts.

[0062] A further technical solution of the present invention is: in the step two, the pressure sensor continuously detects the pressure value applied by the tensioning belt to the mobile structure on the pier surface and feeds back to the control module, the control module determines whether the pressure value is within a preset range, if it is greater than the preset pressure range, the control module controls the cam motor to rotate so that the cam turns from the distal rest surface to the proximal rest surface, so that the tensioning belt is relaxed; if it is less than the preset range, the control module controls the cam motor to rotate so that the cam turns from the proximal rest surface to the distal rest surface, so that the tensioning belt is tightened, if the pressure value is within the preset range, the control module controls the cam tensioning structure to stop adjusting the tensioning belt and proceeds to step three.

[0063] A further technical solution of the present invention is: in the step three, the control module controls the detection marking structure to start, the disc connected to the rotating shaft of the detection motor in the detection marking structure drives the steel ball to start knocking on the pier surface, the sound sensor starts to collect the detection signal, and transmits the detection signal to the signal processing unit for feature parameter extraction.

[0064] A further technical solution of the present invention is: in the step four, the control unit determines whether there is a defect based on the comparison of the extracted characteristic parameters with the threshold value. If so, the control unit controls the marking component to energize the electromagnet, and the electromagnet and the permanent magnet attract each other to pull the rod and press the nozzle to mark the defect; if not, the electromagnet is not energized.

[0065] Beneficial effects of the present invention:

[0066] 1. The mobile structure in the detection system described in the present invention moves on the bridge pier, and the mobile structures are connected by tension belts to form a ring. The fastening pressure value between the mobile structure and the bridge pier is fed back to the control module through the pressure sensor, so that the rotation of the cam is adjusted by the control module to ensure that there is always enough friction between the mobile structure and the bridge pier surface to ensure the stable movement of the mobile structure, so that it is suitable for variable-section and constant-section bridge piers;

[0067] 2. The mobile structure of the present invention realizes the detection of variable-section bridge piers through the cam tensioning structure. The size parameters of the cam are determined according to the slope of the bridge pier to be detected and the number of mobile structures. Flexible detection can be realized for cylindrical bridge piers of different sizes and bridge piers of variable sections, avoiding the addition of guide rails, cantilevers and other mechanisms, reducing the detection cost and preliminary preparation work, and reducing the error in the measurement process. The tensioning belt is adjusted by the rotation of the cam to ensure that the mobile structure can run stably on the bridge pier surface;

[0068] 3. The mobile structure provided by the present invention uses a disc to drive a steel ball to knock on the wall surface of the pier, and cooperates with a plurality of steel balls of different sizes to meet the detection of defects of different depths, quickly generates dense impact points, and reduces the probability of missed defect detection;

[0069] 4. The mobile structure of the present invention instantly marks the defective part through the detection and marking structure. The control module determines whether there is a defect through the signal fed back by the signal processing module. After the defect signal is detected, the control marking module energizes the electromagnet. After the electromagnet is energized, it attracts the permanent magnet and pulls the pull rod to press the nozzle to mark the detected part, which is convenient for the staff to carry out subsequent repair processing and reduces the subsequent workload. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 The tightening of the tensioning belt provided by the present invention is reflected in the change of the circumference;

[0071] Figure 2 It is a schematic diagram of the working state of a bridge pier defect detection system based on the impact echo method provided by the present invention;

[0072] Figure 3 is a structural schematic diagram of a mobile structure provided by the present invention;

[0073] Figure 4 is a structural schematic diagram of a signal detection component provided by the present invention;

[0074] Figure 5 It is a structural schematic diagram of the marking component provided by the present invention;

[0075] Figure 6 It is a flow chart of a bridge pier defect detection method based on the impact echo method provided by the present invention.

[0076] Figure numerals: 1. moving structure, 2. tensioning belt, 3. seat, 4. control module, 5. cam tensioning structure, 6. signal detection component, 7. marking component, 8. travel component, 41. control unit, 42. signal processing unit, 51. static pulley, 52. static pulley support, 53. cam support, 54. pressure sensor, 55. cam motor, 56. cam, 61. sound sensor, 62. protective cover, 63. detection motor, 64. disc, 65. spring, 66. steel ball, 67. laser ranging sensor, 71. electromagnet, 72. permanent magnet, 73. spray pot, 74. pull rod, 75. nozzle, 81. wheel, 82. support. DETAILED DESCRIPTION

[0077] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0078] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0079] Embodiment 1:

[0080] Figure 2-5 A bridge pier defect detection system based on the impact echo method is shown, the detection system comprises a mobile structure 1 and a tension belt 2 which connects a plurality of the mobile structures 1 to form a ring.

[0081] The mobile structure 1 includes a mobile body, a control module 4, a cam tensioning structure 5, and a detection marking structure. The cam tensioning structure 5 is placed on a side of the mobile body away from the bridge pier, and the detection marking structure is placed on a side of the mobile body close to the bridge pier. The mobile body, the cam tensioning structure 5, and the detection marking structure are all electrically connected to the control module 4.

[0082] The cam tensioning structure 5 includes a static pulley group and a cam group, and the cam group includes a pressure sensor 54, a cam support 53 placed on the pressure sensor 54, a cam 56 placed on the cam support 53 and rotatably connected to the cam support 53, and a cam motor 55 driving the cam 56 to rotate. The control module 4 controls the rotation of the cam 56 according to the signal of the pressure sensor 54, and the fastening pressure between the movable structure and the bridge pier is adjustable.

[0083] As a preferred embodiment, the mobile structure is a trolley. There are several trolleys, and the specific number is determined according to the size of the pier to be inspected. Adjacent trolleys are connected by tension belts, and each trolley is individually controlled and evenly distributed at 30 cm to 60 cm intervals along the circumference of the pier cross-section to achieve the best detection effect.

[0084] In this embodiment, the cam parameter design is based on the slope of the pier to be inspected and the number of moving structures to meet the requirements of variable-section pier inspection. The designed cam satisfies the following requirements: when the cam rotates through the thrust angle and the working surface of the cam turns from the near rest surface to the far rest surface, the moving structure completes the inspection from the bottom of the pier to the top. Conversely, the trolley completes the return from the top to the bottom of the pier.

[0085] In this embodiment, the pressure sensor 54 feeds back the detected pressure value to the control module, and the control module 4 controls the cam motor 55 to rotate and adjust the tightness of the tension belt 2 according to whether the pressure value is within a preset range. If the pressure value is greater than the preset pressure range, the control module 4 controls the cam motor 55 to rotate so that the cam 56 turns from the distal rest surface to the proximal rest surface to relax the tension belt 2; if the pressure value is less than the preset range, the control module 4 controls the cam motor 55 to rotate so that the cam 56 turns from the proximal rest surface to the distal rest surface to tighten the tension belt 2, thereby ensuring that there is always sufficient friction between the moving structure and the pier surface, thereby ensuring the stable operation of the moving structure.

[0086] The tightening pressure only needs to ensure that the driving force generated by the mobile structure is greater than the friction force exerted on the detection system on the pier wall.

[0087] In this embodiment, the static pulley assembly includes a static pulley support 52 and a static pulley 51 disposed on the static pulley support 52 and rotatably connected to the static pulley support 52 , and the static pulleys 51 on both sides are in the same straight line as the cam 56 .

[0088] As a preferred embodiment, there are two static pulleys 51 symmetrically distributed on both sides of the cam 56 to ensure the stability of the movement of the moving structure 1.

[0089] In this embodiment, the tension belt 2 passes through the bottom of the static pulley 51 , the top of the cam 56 , and the bottom of another static pulley 51 in sequence, and the tension belt 2 is in tensioning contact with the cam tensioning structure 5 .

[0090] In this embodiment, the detection marking structure includes a signal detection component 6 and a marking component 7, and the signal detection component 6 and the marking component 7 are both electrically connected to the control module 4. The signal detection component 6 includes a sound sensor 61, a protective cover 62 placed on the side of the sound sensor 61 close to the pier, a detection motor 63, a rotatable disk 64 connected to the output end of the detection motor 63, and a steel ball 66 connected to the outer periphery of the disk 64 through a spring 65. The top of the detection motor 63 is connected to the mobile body.

[0091] As a preferred embodiment, the sound sensor is 3 cm away from the pier surface.

[0092] In this embodiment, there are multiple steel balls 66 with different diameters. The disk 44 suspends steel balls 66 of various diameters to detect defects of different depths, and drives the steel balls 66 to move centripetally at a certain rotation speed. The steel balls 66 collide with the pier surface along the tangent direction of the disk 64 and rebound and decelerate, and are dragged by the spring 65 to re-rotate and accelerate through the disk 64 to enter the next collision.

[0093] In this embodiment, the signal detection module 6 further includes a laser distance sensor 67, which is placed on the mobile body and electrically connected to the control module 4. The laser distance sensor 67 feeds back the distance between the mobile structure and the top and bottom of the pier to the control module, and the control module determines whether the distance is less than a preset value. If so, the control module controls the mobile structure to stop running, and if not, the mobile structure continues to run.

[0094] In this embodiment, the marking component 7 includes a spray pot 73, a nozzle 75 placed at one end of the spray pot 73, a pull rod 74 connected to the nozzle 75, and an electromagnet 71 placed on the movable body and electromagnetically attracted to the pull rod 74. When the electromagnet 71 is energized, the pull rod 74 presses the nozzle 75 for marking.

[0095] In this embodiment, a permanent magnet 72 is provided at one end of the pull rod 74 connected to the electromagnet 71. If there is a defect, the control module 41 controls the marking component 7 to energize the electromagnet 71. After the electromagnet 71 is energized, it attracts the permanent magnet 72 and pulls the pull rod 74 to press the nozzle 75 to mark the detection part. If there is no defect, the electromagnet 71 is not energized.

[0096] As a preferred embodiment, the marking materials used for marking are not limited to fluorescent agents, inks, etc., as long as they meet the marking function and do not damage the bridge piers.

[0097] In this embodiment, the mobile structure 1 includes a seat 3 and a traveling assembly 8 disposed on the side of the seat 3 close to the bridge pier. The traveling assembly 8 includes support members 82 and wheels 81 disposed between the support members 82 and rotatably connected to the support members 82 .

[0098] In this embodiment, the control module 4 includes a control unit 41 and a signal processing unit 42 electrically connected to the control unit 41 .

[0099] In this embodiment, the signal processing unit 42 extracts characteristic parameters of the signal collected by the sound sensor 61 and sends them to the control unit 41. The control unit 41 compares the extracted characteristic parameters with a threshold value to determine whether there is a defect. The threshold value is determined by an empirical value.

[0100] As a preferred embodiment, the control unit 41 is connected to a local terminal, and the local terminal has a practical function, which is convenient for technicians to process data, manually intervene in the operation status of small plans and other subsequent work.

[0101] Embodiment 2:

[0102] The cam parameter design in the first embodiment of the present invention is determined according to the slope of the pier to be detected, and the design is based on the following steps:

[0103] Step 1: Determine the Cam's Working Requirements

[0104] In order to detect cylindrical bridge piers with slopes, after the cam rotates through a certain angle δ0, the push stroke h of the cam push rod should be 5cm to 10cm greater than the difference between the upper and lower cross-sectional radii of the bridge pier;

[0105] Step 2: Determine the cam motion pattern

[0106] Given the pier body slope, it is determined that the cam's push motion law is constant velocity motion. The motion equation is:

[0107] s = hδ / δ0;

[0108] v=hω / δ0;

[0109] a=0;

[0110] In the formula, s is the displacement of the push rod in the horizontal direction, h is the push stroke, δ is the angle of the cam, δ0 is the push stroke angle, v is the speed of the push rod in the horizontal direction, which is determined by the speed of the trolley. ω is the angular velocity of the cam rotation, and a is the acceleration of the push rod;

[0111] The tightening of the tensioning belt is reflected in the change of the circumference. As shown in 1, when the cam rotates a certain angle, the change of the circumference is approximately the change of the hypotenuse of the triangle on the way. In the initial state, the lengths of a, b, and c are known. When the horizontal displacement is s, the change of the circumference of the tensioning belt is:

[0112]

[0113] Where n is the number of mobile structures.

[0114] In actual situations, the change in circumference radius is:

[0115] R`=d` / 2П

[0116] Therefore, the actual deduction process is:

[0117] h s =R`max

[0118] Step 3: Determine the Cam Profile Equation

[0119] For the concentric translation pointed push rod disc cam mechanism, the theoretical profile of the cam is:

[0120] x=(r0+s)sinδ

[0121] y=(r0+s)cosδ

[0122] Among them, r0 is the base circle radius, s is the displacement of the push rod, and δ is the angle of rotation of the cam.

[0123] Embodiment three:

[0124] like Figure 6 As shown, a method for detecting bridge pier defects based on the impact echo method is provided. The method is based on the bridge pier defect detection system described in Example 1, and the method comprises the following steps:

[0125] Step 1: Install the mobile structure around the bridge pier through the tensioning belt, with intervals between the mobile structures;

[0126] Step 2: The pressure sensor continuously detects the pressure value applied by the tensioning belt to the mobile structure on the bridge pier and feeds it back to the control module. The control module determines whether the pressure value is within a preset range according to the pressure value, controls the rotation of the cam motor through the control module, and adjusts the tension of the cam and the tensioning belt until it is within the setting range of the controller.

[0127] Step 3: The control module controls the movement of the mobile body, and the detection marking structure monitors the distance between the mobile structure and the top of the pier in real time and feeds back to the control module;

[0128] Step 4: The control module controls the detection and marking structure to detect the bridge pier, transmits the detection signal to the control module for processing, determines whether there are defects, and marks the defective areas;

[0129] Step 5: The control module determines the distance between the mobile structure and the top of the bridge pier according to the signal fed back by the detection marking structure, so as to determine whether the detection of the bridge pier is completed. If yes, proceed to the next step; if not, repeat steps 3 to 5;

[0130] Step 6: After the detection is completed, the control module controls the mobile structure to stop and completes the detection of the bridge pier.

[0131] In this embodiment, in step 1, the movable structures and the tension belts are installed around the bridge piers, the movable structures are evenly distributed along the circumference of the pier wall at intervals of 30 cm to 60 cm, and the movable structures are connected by tension belts.

[0132] In the present embodiment, in the step 2, the pressure sensor continuously detects the pressure value applied by the tensioning belt to the mobile structure on the pier surface and feeds back to the control module, and the control module determines whether the pressure value is within a preset range. If it is greater than the preset pressure range, the control module controls the cam motor to rotate so that the cam turns from the distal rest surface to the proximal rest surface to relax the tensioning belt; if it is less than the preset range, the control module controls the cam motor to rotate so that the cam turns from the proximal rest surface to the distal rest surface to tighten the tensioning belt. If the pressure value is within the preset range, the control module controls the cam tensioning structure to stop adjusting the tensioning belt and proceeds to step 3.

[0133] In this embodiment, the control module in step three controls the detection marking structure to start, the disc connected to the rotating shaft of the detection motor in the detection marking structure drives the steel ball to start knocking on the pier surface, the sound sensor starts to collect the detection signal, and transmits the detection signal to the signal processing unit for feature parameter extraction.

[0134] In this embodiment, in step four, the control unit determines whether there is a defect based on the comparison of the extracted characteristic parameters with the threshold value. If so, the control unit controls the marking component to energize the electromagnet, and the electromagnet and the permanent magnet attract each other to pull the rod and press the nozzle to mark the defect; if not, the electromagnet is not energized.

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bridge pier defect detection system based on impact echo method, characterized in that: The detection system comprises a mobile structure (1) and a tensioning belt (2) connecting a plurality of the mobile structures (1) to form a ring. The mobile structure (1) comprises a mobile body, a control module (4), a cam tensioning structure (5), and a detection marking structure. The cam tensioning structure (5) is disposed on a side of the mobile body away from the bridge pier, and the detection marking structure is disposed on a side of the mobile body close to the bridge pier. The mobile body, the cam tensioning structure (5), and the detection marking structure are all electrically connected to the control module (4). The cam tensioning structure (5) comprises a static pulley group and a cam group, the cam group comprises a pressure sensor (54), a cam support (53) disposed on the pressure sensor (54), a cam (56) disposed on the cam support (53) and rotatably connected to the cam support (53), and a cam motor (55) driving the cam (56) to rotate, the control module (4) controls the rotation of the cam (56) according to a signal from the pressure sensor (54), and the fastening pressure between the mobile structure and the bridge pier is adjustable; The static pulley assembly comprises a static pulley support (52) and a static pulley (51) placed on the static pulley support (52) and rotatably connected to the static pulley support (52), wherein the static pulleys (51) on both sides are located on the same straight line as the cam (56); The tensioning belt (2) passes through the bottom of the static pulley (51), the top of the cam (56) and the bottom of another static pulley (51) in sequence, and the tensioning belt (2) is in tensioning contact with the cam tensioning structure (5).

2. The bridge pier defect detection system based on the impact echo method according to claim 1 is characterized in that: The detection marking structure comprises a signal detection component (6) and a marking component (7), the signal detection component (6) and the marking component (7) are both electrically connected to the control module (4), the signal detection component (6) comprises a sound sensor (61), a protective cover (62) disposed on a side of the sound sensor (61) close to the bridge pier, a detection motor (63), a rotatable disk (64) disposed at the output end of the detection motor (63), and a steel ball (66) connected to the outer periphery of the disk (64) via a spring (65), and the top end of the detection motor (63) is connected to the mobile body.

3. The bridge pier defect detection system based on the impact echo method according to claim 2 is characterized in that: There are multiple steel balls (66) with different diameters.

4. The bridge pier defect detection system based on the impact echo method according to claim 2 is characterized in that: The signal detection component (6) further comprises a laser distance measuring sensor (67), wherein the laser distance measuring sensor (67) is disposed on the mobile body and is electrically connected to the control module (4).

5. The bridge pier defect detection system based on the impact echo method according to claim 2 is characterized in that: The marking component (7) comprises a spray pot (73), a nozzle (75) disposed at one end of the spray pot (73), a pull rod (74) connected to the nozzle (75), and an electromagnet (71) disposed on the movable body and electromagnetically attracted to the pull rod (74); when the electromagnet (71) is energized, the pull rod (74) presses the nozzle (75) for marking.

6. The bridge pier defect detection system based on the impact echo method according to claim 1 is characterized in that: The mobile structure (1) comprises a seat (3), a traveling assembly (8) disposed on a side of the seat (3) close to the bridge pier, and the traveling assembly (8) comprises support members (82) and wheels (81) disposed between the support members (82) and rotatably connected to the support members (82).

7. The bridge pier defect detection system based on the impact echo method according to claim 1 is characterized in that: The control module (4) comprises a control unit (41) and a signal processing unit (42) electrically connected to the control unit (41).

8. A method for detecting bridge pier defects based on the impact echo method, the method being based on the bridge pier defect detection system according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Step 1: Install the mobile structure around the bridge pier through the tensioning belt, with intervals between the mobile structures; Step 2: The pressure sensor continuously detects the pressure value applied by the tensioning belt to the mobile structure on the bridge pier and feeds it back to the control module. The control module determines whether the pressure value is within a preset range according to the pressure value, controls the rotation of the cam motor through the control module, and adjusts the tension of the cam and the tensioning belt until it is within the setting range of the controller. Step 3: The control module controls the movement of the mobile body, and the detection marking structure monitors the distance between the mobile structure and the top of the pier in real time and feeds back to the control module; Step 4: The control module controls the detection and marking structure to detect the bridge pier, transmits the detection signal to the control module for processing, determines whether there are defects, and marks the defective areas; Step 5: The control module determines the distance between the mobile structure and the top of the bridge pier according to the signal fed back by the detection marking structure, so as to determine whether the detection of the bridge pier is completed. If yes, proceed to the next step; if not, repeat steps 3 to 5; Step 6: After the detection is completed, the control module controls the mobile structure to stop and completes the detection of the bridge pier.

Images