A kind of bridge steel concrete joint segment void condition monitoring instrument and its construction method

Abstract

The present application relates to bridge detection technical field, specifically for a kind of for bridge steel and mix combination section void condition monitoring instrument and its construction method, comprising: surface-mounted strain gauge, surface-mounted strain gauge is provided with multiple;Strain gauge assembly is arranged on the outer side of mounting plate, and both ends of strain gauge assembly are fixedly connected with mounting plate by mounting bracket;Two parallelly arranged reflecting plates are installed in the inner cavity of shell body, reflecting plate is "<" shape, and the surface of two reflecting plates close to each other is provided with reflective layer;Beneficial effect is: by dividing steel and mix combination section void region to be measured, a column of surface-mounted strain gauge for monitoring parameter is arranged on each divided region, since laser beam will experience multiple reflections between two reflecting plates, initial emission angle can be amplified, so that the deformation of void region can be detected more accurately, the present apparatus has the characteristics of accurate data, easy to install, and the detection effect is good, and the reliability of detection conclusion is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge detection, in particular to a bridge steel-concrete joint segment void condition monitoring instrument and a construction method thereof. BACKGROUND

[0002] In the field of modern bridge construction, steel-concrete joint segments are increasingly applied in more and more scenarios. Steel-concrete joint segments are made of different materials to form a whole structure and work together, and have better characteristics than single material structures. Steel-concrete composite structure type bridges have good technical features and high cost-effectiveness compared to other types of bridges, and are not only suitable for large-span bridge construction, but also have strong competitiveness in small and medium-span bridge construction.

[0003] In the prior art, during the construction process and later use of the steel-concrete joint segment, due to the long-term repeated action of vehicles, the steel plate and the concrete in the local area may be subjected to tension phenomenon, and when the tension exceeds a certain degree or is affected by other factors, the steel plate and the concrete in these areas may be separated, i.e. the so-called void phenomenon. At present, there are many methods for identifying voids at home and abroad, such as the knocking method by manually knocking the surface of the detected object, the magnetic powder flaw detection method by applying magnetic powder to the surface of the concrete and then detecting it with a magnetic instrument after drying, and the drilling sampling method by drilling and coring.

[0004] However, due to the special material properties and complex structure of the steel-concrete joint segment, the above methods have great limitations in actual application. The knocking method is highly subjective, and its accuracy is related to the proficiency of the staff, which can easily lead to misjudgment. The magnetic powder flaw detection method is difficult to obtain accurate results due to the complex structure of the steel-concrete joint segment, the non-uniformity of the concrete material, and the numerous structural components. The drilling sampling method is a local damage detection method, and multiple drilling holes can cause significant damage to the structure, so it is generally used for secondary confirmation or sampling investigation in engineering. Therefore, these methods cannot be completely applied. Therefore, the present application proposes a bridge steel-concrete joint segment void condition monitoring instrument and a construction method thereof to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a bridge steel-concrete joint segment void condition monitoring instrument and a construction method thereof to solve the problem of the great limitations of the traditional void detection methods proposed in the background.

[0006] To achieve the above purpose, the present application provides the following technical solution: a bridge steel-concrete joint segment void condition monitoring instrument, comprising:

[0007] A surface-mounted strain gauge is provided, and a plurality of surface-mounted strain gauges are arranged at equal intervals on the web and the bottom plate of the steel-concrete joint segment.

[0008] The surface-mounted strain gauge comprises a mounting plate fixedly connected with the surface of the steel-concrete combined section, and a strain gauge assembly is arranged outside the mounting plate, and both ends of the strain gauge assembly are fixedly connected with the mounting plate through mounting racks;

[0009] The strain gauge assembly comprises an outer housing, two parallel arranged reflection plates are mounted in the inner cavity of the outer housing, the reflection plates are in "<" shape, and the surfaces of the two reflection plates close to each other are both provided with reflection layers, and a laser emitter and a laser receiver are arranged at the two ends of the outer housing respectively, and the laser beam emitted by the laser emitter is irradiated on the surface of one reflection layer at an angle of forty-five degrees and is irradiated on the laser receiver after reflection.

[0010] Preferably, mounting sleeves and open spherical shells are fixedly connected with the two ends of the outer housing respectively, the outer side of the laser receiver is provided with threads and is screwed into the inner cavity of the mounting sleeve, the mounting sleeve is in communication with the inner cavity of the outer housing, and a transparent glass plate is arranged at the connection position.

[0011] Preferably, a fixing cylinder is fixedly connected with the surface of the laser receiver, one end of the fixing cylinder extends to the outer side of the mounting sleeve and is fixedly connected with a knob, the knob abuts against the end face of the mounting sleeve, and an annular sealing gasket is arranged between the two, and a receiver cable electrically connected with the laser receiver is arranged in the inner cavity of the fixing cylinder.

[0012] Preferably, a connecting ball is arranged at the outer side of the end of the laser emitter, and the two are fixedly connected through a hollow connecting cylinder, the connecting ball is rotatably mounted in the inner cavity of the open spherical shell and is adapted thereto, a through hole is formed in the middle of the connecting ball, the laser beam emitted by the laser emitter enters the inner cavity of the outer housing through the through hole, a protective hose is fixedly connected with the end face of the laser emitter, and one end of the protective hose is fixed to the surface of the outer housing.

[0013] Preferably, a stop ring one is fixedly connected with the outer side of the mounting sleeve, and a stop ring two is fixedly connected with the outer side of the laser emitter, the mounting racks comprise two arc-shaped clamping pieces which are symmetrically arranged and are spliced into a circular ring shape, and two groups of the mounting racks are fixedly sleeved on the outer side of the mounting sleeve and the outer side of the laser emitter respectively.

[0014] Preferably, an arc-shaped pad is adhesively fixed to the inner wall of the arc-shaped clamping piece, a connecting block and a protruding block are fixedly connected with the two ends of the arc-shaped clamping piece respectively, connecting holes are formed in the surfaces of the connecting block and the protruding block, and the two arc-shaped clamping pieces are fixedly connected through bolts.

[0015] Preferably, one end of the connecting block is fixedly connected with a connecting plate, a long strip-shaped waist hole is formed in the surface of the connecting plate, a shock pad is fixedly connected to the surface of the connecting plate away from the connecting block, a fixing stud corresponding to the waist hole is fixedly connected to the surface of the mounting plate, the connecting plate and the fixing stud are fixedly connected through a nut, a gasket is arranged between the nut and the connecting plate, and the two fixing studs are connected together as a group through the gasket at both ends.

[0016] Preferably, the outer shell is provided with an opening on one side surface, and a cover plate is fixedly connected to the opening through bolts, the inner wall of the outer shell is fixedly provided with a positioning block, and the positioning block abuts against and positions the surface of the reflecting plate.

[0017] A construction method for the bridge steel-concrete joint segment void condition monitoring instrument according to the above, specifically comprising the following steps:

[0018] Step one, judging the steel-concrete joint segment void distribution area:

[0019] Based on stress analysis, stress analysis is performed on different parts of the steel-concrete joint segment, and it is concluded that the area with large normal stress is prone to void;

[0020] Based on construction analysis, there is vibration in the construction process, which leads to incomplete compaction, resulting in local concrete at the corners not being able to be bonded together;

[0021] Combined with the material properties, settlement and inclination of the steel-concrete joint segment to be measured, the finite element calculation and analysis results of the steel-concrete joint segment are used to select the area with void for the following strain monitoring;

[0022] Step two, determining the placement method of the surface-mounted strain gauge:

[0023] According to the size, settlement and detection requirements of the steel-concrete joint segment, the steel-concrete joint segment void to be measured area is divided;

[0024] A column of surface-mounted strain gauges for monitoring parameters is placed on each divided area;

[0025] Step three, collecting parameter information and positioning monitoring of the void part:

[0026] All the data collected by the surface-mounted strain gauges for detection are summarized, and the collected information data are processed to be visually displayed in the form of images;

[0027] Once the strain value of a certain point changes suddenly, it can be determined that void damage may occur at this point, and the void area range can be preliminarily determined by comparing the strain of the adjacent points;

[0028] When more accurate positioning is required, the detection area where the possible void position is located is further divided into smaller detection areas in the same division manner, and the above operation is repeated.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The present application divides the void-to-be-tested area of the steel-concrete joint section, and arranges a row of surface-mounted strain gauges for monitoring parameters on each divided area. The surface-mounted strain gauge comprises a mounting plate, a mounting frame and a strain gauge assembly. The strain gauge assembly comprises an outer shell and two reflection plates installed in the inner cavity of the outer shell. The outer shell is provided with a laser emitter and a laser receiver at two ends, respectively. The reflection plates are in the shape of ">". The surfaces of the two reflection plates close to each other are provided with reflection layers. The laser beam emitted by the laser emitter and located between the two reflection plates can be reflected to the laser receiver. When the installation position of the surface-mounted strain gauge is voided, the steel plate inside the steel-concrete joint section at this position will be outwardly normal bulged, so as to change the angle of the laser beam emitted by the laser emitter. Since the laser beam will undergo multiple reflections between the two reflection plates, the initial emission angle can be amplified, so that the deformation of the voided area can be more accurately detected. Compared with the traditional detection method, the present device has the characteristics of accurate data and easy installation, without the need for large detection equipment, and can accurately position the voided position of the steel-concrete joint section, with good detection effect and high reliability of detection conclusion. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structural distribution position of the present application.

[0032] Figure 2 It is a schematic diagram of the structure of the surface-mounted strain gauge of the present application.

[0033] Figure 3 It is an exploded schematic diagram of the structure of the surface-mounted strain gauge of the present application.

[0034] Figure 4 It is a schematic diagram of the structure of the mounting frame of the present application.

[0035] Figure 5 It is an exploded schematic diagram of the structure of the strain gauge assembly of the present application.

[0036] Figure 6 It is a schematic diagram of the internal structure of the outer shell of the present application.

[0037] Figure 7 It is a schematic diagram of the structure of the laser emitter of the present application.

[0038] Figure 8 It is a schematic diagram of the reflection path of the laser beam of the present application.

[0039] Figure 9Strain variation curve of a column position of the bottom plate of the steel-concrete joint section of the application;

[0040] Figure 10 Strain variation curve of b column position of the bottom plate of the steel-concrete joint section of the application;

[0041] Figure 11 Strain variation curve of c column position of the web of the steel-concrete joint section of the application;

[0042] Figure 12 Strain variation curve of d column position of the web of the steel-concrete joint section of the application;

[0043] Figure 13 Construction process schematic diagram of the application.

[0044] In the figure: 1, surface-mounted strain gauge; 2, mounting plate; 21, fixing stud; 22, backing plate; 3, mounting frame; 31, arc-shaped clamping piece; 32, arc-shaped backing; 33, connecting block; 331, protruding block; 332, connecting hole; 34, connecting plate; 35, waist hole; 36, shockproof pad; 4, strain gauge assembly; 41, outer shell; 411, mounting sleeve; 412, open spherical shell; 413, stop ring one; 414, positioning block; 415, cover plate; 42, reflecting plate; 421, reflecting layer; 43, laser emitter; 431, connecting ball; 432, connecting cylinder; 433, through hole; 434, protective hose; 435, stop ring two; 44, laser receiver; 441, fixing cylinder; 442, knob; 443, receiver cable. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions of the application clear and complete, and the advantages more clear and obvious, the embodiments of the application are further described in detail below with reference to the drawings. It should be understood that the specific embodiments described here are part of the embodiments of the application, not all the embodiments, and are only used to explain the embodiments of the application, and are not used to limit the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0046] In the description of the present application, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "one", "first", "second", "third", "fourth", "fifth", "sixth" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0047] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] For the purpose of simplicity and illustration, the principles of the embodiments are mainly described by referring to examples. In the following description, many specific details are presented to provide a thorough understanding of the embodiments. However, it is obvious to those skilled in the art that the embodiments can not be limited to these specific details in practice. In some examples, well-known methods and structures are not described in detail to avoid unnecessarily complicating the embodiments. In addition, all embodiments can be used in combination with each other.

[0049] Please refer to Figures 1 to 8 The present application provides a technical solution:

[0050] Embodiment one, a kind of for bridge steel and concrete joint segment void condition monitoring instrument, comprising:

[0051] Surface-mounted strain gauge 1, surface-mounted strain gauge 1 is set multiple, and it is equally spaced distribution at the web and bottom plate of steel and concrete joint segment, as shown in Figure 1 Surface-mounted strain gauge 1 can be linearly distributed at equal intervals or rectangular array according to actual needs, in addition, since bridge steel and concrete joint segment is usually left-right symmetrical distribution structure, therefore surface-mounted strain gauge 1 can be installed only in the web and half of the bottom plate of steel and concrete joint segment on one side;

[0052] Secondly, the surface-mounted strain gauge 1 comprises a mounting plate 2 fixedly connected with the surface of the steel-concrete joint segment, the fixing between the mounting plate 2 and the steel-concrete joint segment can be achieved by means of glue bonding or expansion bolt fixing, the outer side of the mounting plate 2 is provided with a strain gauge assembly 4, both ends of the strain gauge assembly 4 are fixedly connected with the mounting plate 2 through mounting racks 3, the mounting racks 3 are used for mounting and positioning the strain gauge assembly 4, and the specific structure of the mounting racks 3 and the strain gauge assembly 4 will be described below;

[0053] Specifically, the strain gauge assembly 4 comprises an outer shell 41, two parallel reflection plates 42 are arranged in the inner cavity of the outer shell 41, the reflection plates 42 are in the shape of "<", and the surfaces close to each other of the two reflection plates 42 are provided with reflection layers 421, as shown in Figure 5 and Figure 6 The two halves of the reflection plates 42 are perpendicular to each other, the two ends of the outer shell 41 are respectively provided with a laser emitter 43 and a laser receiver 44, the laser beam emitted by the laser emitter 43 is irradiated on the surface of one reflection layer 421 at an angle of forty-five degrees, and is irradiated on the laser receiver 44 after reflection, as shown in Figure 8 The laser beam is irradiated on one reflection layer 421 at an angle of forty-five degrees, and is emitted out of the same axis and direction after four reflections between the two reflection plates 42, and is finally received by the laser receiver 44, when the incidence angle of the laser beam changes, the multiple reflections of the laser beam will amplify the error after reflection (the error here refers to the distance of the laser beam deviating from the initial position), so as to ensure that the device can accurately detect the slight deformation of the void of the steel-concrete joint segment, thereby improving the reliability of the detection conclusion.

[0054] In order to mount, position and protect the laser receiver 44, the application also has mounting sleeves 411 and open spherical shells 412 fixedly connected with the two ends of the outer shell 41 respectively, the outer side of the laser receiver 44 is provided with threads and is screwed into the inner cavity of the mounting sleeve 411, as shown in Figure 5 and Figure 6 The mounting sleeve 411 is used for mounting, positioning and protecting the laser receiver 44, the inner cavity of the mounting sleeve 411 is in communication with the inner cavity of the outer shell 41, and a transparent glass plate is arranged at the connection position, so as to ensure that the laser beam can pass through the inner wall of the outer shell 41 and irradiate on the laser receiver 44.

[0055] In order to avoid water entering the laser receiver 44, the application also has a fixing cylinder 441 fixedly connected with the surface of the laser receiver 44, one end of the fixing cylinder 441 extends to the outer side of the mounting sleeve 411 and is fixedly connected with a knob 442, when the laser receiver 44 is mounted, the staff can tighten the knob 442, the knob 442 abuts against the end face of the mounting sleeve 411, and an annular sealing gasket is arranged between the knob 442 and the mounting sleeve 411, so as to avoid water entering the inner cavity of the mounting sleeve 411, and the inner cavity of the fixing cylinder 441 is also provided with a receiver cable 443 electrically connected with the laser receiver 44.

[0056] To restrict the movement of the laser emitter 43, this application further includes a connecting ball 431 provided on the outer side of the end of the laser emitter 43, and the two are fixedly connected by a hollow connecting cylinder 432. The connecting ball 431 is rotatably mounted in and adapted to the inner cavity of the open spherical shell 412, and in combination with... Figure 7 and Figure 5 As shown, the laser emitter 43 can move outside the outer shell 41, and its movement is restricted by the open spherical shell 412 and the connecting ball 431. That is, the laser emitter 43 can only rotate around the center of the open spherical shell 412 and the connecting ball 431. A through hole 433 is provided in the middle of the connecting ball 431. The laser beam emitted by the laser emitter 43 passes through the through hole 433 and enters the inner cavity of the outer shell 41, which can prevent the laser beam emitted by the laser emitter 43 from being blocked by the side wall of the outer shell 41. In addition, the movement of the laser emitter 43 will change the emission angle of the laser beam for subsequent detection. A protective hose 434 is fixedly connected to the end face of the laser emitter 43. One end of the protective hose 434 is fixed to the surface of the outer shell 41. The protective hose 434 itself has deformation capability and can adapt to the rotation and movement of the laser emitter 43. The protective hose 434 is used to protect the end of the laser emitter 43.

[0057] In order to install the strain gauge assembly 4, this application also has a retaining ring 413 fixedly connected to the outside of the mounting sleeve 411, a retaining ring 435 fixedly connected to the outside of the laser emitter 43, and a mounting frame 3 including two symmetrically arranged arc-shaped clamping members 31 that are joined into a ring shape. The two sets of mounting frames 3 are respectively fixedly sleeved on the outside of the mounting sleeve 411 and the outside of the laser emitter 43. The two sets of mounting frames 3 clamp and position the two ends of the strain gauge assembly 4 to ensure that the strain gauge assembly 4 can be correctly installed on the surface of the steel-concrete composite section.

[0058] To provide a detailed description of the structure of the mounting bracket 3, this application also includes an arc-shaped pad 32 bonded and fixed to the inner wall of the arc-shaped clamping member 31, used to protect the mounting sleeve 411 and the laser emitter 43 from excessive compressive force and damage. Connecting blocks 33 and protrusions 331 are fixedly connected to both ends of the arc-shaped clamping member 31, respectively. Connecting holes 332 are provided on the surfaces of both the connecting blocks 33 and the protrusions 331. The two arc-shaped clamping members 31 are fixedly connected by bolts. Figure 4 and Figure 3 It can be seen that the mounting bracket 3 is symmetrically arranged as a whole, which can clamp and fix the strain gauge assembly 4.

[0059] In order to connect the mounting frame 3 with the mounting plate 2, the application also has a connecting plate 34 fixedly connected at one end of the connecting block 33, the surface of the connecting plate 34 is provided with an elongated waist hole 35, the surface of the connecting plate 34 away from the connecting block 33 is adhesively fixed with a shock pad 36, the surface of the mounting plate 2 is fixedly connected with a fixed stud 21 corresponding to the waist hole 35, the connecting plate 34 and the fixed stud 21 are fixedly connected through a nut, as shown in Figure 3 and Figure 4 The mounting frame 3 is mounted on the surface of the mounting plate 2, the mounting frame 3 can be finely adjusted in position along the length direction of the waist hole 35, the nut and the connecting plate 34 are provided with a pad 22, the two fixed studs 21 at both ends are connected together in a group, which can improve the stability of the connection between the mounting frame 3 and the mounting plate 2.

[0060] In order to facilitate the installation of the reflecting plate 42, the application also has an opening provided on one side surface of the outer shell 41, and a cover plate 415 is fixedly connected to the opening through a bolt, as shown in Figure 5 The cover plate 415 can be detachably mounted, so that the reflecting plate 42 is installed into the inner cavity of the outer shell 41, the inner wall of the outer shell 41 is fixedly provided with a positioning block 414, the positioning block 414 abuts against the surface of the reflecting plate 42 and positions the reflecting plate 42, and the positioning block 414 is provided to avoid the reflecting plate 42 from shaking and position deviation in the inner cavity of the outer shell 41, thereby affecting the reflection path of the laser beam.

[0061] The application also discloses a construction method of the bridge steel-concrete joint segment void condition monitoring instrument.

[0062] Step one, judging the steel-concrete joint segment void distribution area:

[0063] Based on stress analysis, stress analysis is performed on different parts of the steel-concrete joint segment, and it is concluded that the area with large normal stress is prone to void;

[0064] Based on construction analysis, there is vibration and non-compactness in the construction process, so that the local concrete at the corners and the like cannot be bonded together;

[0065] Combined with the material properties, settlement and inclination of the steel-concrete joint segment to be measured, the finite element calculation and analysis results of the steel-concrete joint segment are used to select the area with void for the following strain monitoring;

[0066] In the example, the steel-concrete joint segment is 3 m long, 6.48 m high, 12.6 m wide at the top plate and 7 m wide at the bottom plate, and the bottom plate and the web are selected as the detection area through finite element software analysis;

[0067] Step two, determining the arrangement mode of the surface-mounted strain gauge 1:

[0068] According to the size, settlement and detection requirements of the steel-concrete joint section, the region division of the void detection area of the steel-concrete joint section is carried out; in this example, as shown in Figure 1 the bottom plate and the web of the detection area are divided into two regions, respectively located at the center of the bottom plate and the web and the position 0.15 m away from the corner;

[0069] A column of table-mounted strain gauges 1 for monitoring parameters is arranged on each divided region; in the divided region, two table-mounted strain gauges 1 are arranged on the bottom plate and the web, respectively, and nine table-mounted strain gauges 1 are arranged on the steel-concrete joint section of 3 m in length in the bridge direction at equal intervals with an interval of 0.3 m (for the convenience of recording, the table-mounted strain gauge 1 arranged at the center of the bottom plate and the position 0.15 m away from the corner is respectively marked as column a and column b, and the table-mounted strain gauge 1 arranged at the center of the web and the position 0.15 m away from the corner is respectively marked as column c and column d);

[0070] Step three, collecting parameter information, and positioning monitoring of the void part:

[0071] All the data collected by the table-mounted strain gauges 1 for detection are summarized, and then the collected information data are processed to be visually displayed in the form of images;

[0072] Once the strain value of a certain point changes suddenly, it can be determined that the void damage may occur at this place, and the void region range can be preliminarily determined by comparing with the strain of the adjacent points; as shown in Figure 9 and Figure 10 the strain change curve of the table-mounted strain gauge 1 in column a appears mutation at 0.3 m, and the strain of column a after 0.3 m and column b which is not voided increases slowly and maintains a certain rule, so it can be preliminarily judged that the void appears at the center of the bottom plate of the steel-concrete joint section in the bridge direction at 0.3 m, and the approximate void region can be obtained by comparing the adjacent points; as shown in Figure 11 and Figure 12 the strain change curve of the table-mounted strain gauge 1 in column d appears mutation at 0.9 m, and the strain change of column d after 0.9 m and column c which is not voided is uniform, so it can be preliminarily judged that the void appears at the position 0.9 m away from the corner of the web of the steel-concrete joint section in the bridge direction, and the approximate void region can be obtained by comparing the adjacent points;

[0073] as shown in Figure 13 when more accurate positioning is needed, the detection area where the possible void part is located is further divided into smaller detection areas in the same division manner, and the above operation is repeated.

[0074] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A kind of for bridge steel and concrete joint segment void condition monitoring instrument, it is characterized in that: Include: Surface-mounted strain gauge (1), a plurality of and in the web and the bottom plate of the steel-concrete joint section are distributed at equal intervals; The surface-mounted strain gauge (1) comprises a mounting plate (2) fixedly connected with the surface of the steel-concrete joint section, and a strain gauge assembly (4) is arranged outside the mounting plate (2), and the two ends of the strain gauge assembly (4) are fixedly connected with the mounting plate (2) through mounting racks (3); The strain gauge assembly (4) comprises an outer shell (41), two parallel reflective plates (42) are arranged in the inner cavity of the outer shell (41), the reflective plates (42) are in "<" shape, and the surfaces close to each other of the two reflective plates (42) are provided with reflective layers (421), and the two ends of the outer shell (41) are respectively provided with a laser emitter (43) and a laser receiver (44), the laser beam emitted by the laser emitter (43) is irradiated on one reflective layer (421) surface at an angle of forty-five degrees, and is irradiated on the laser receiver (44) after reflection; The two ends of the outer shell (41) are respectively fixedly connected with a mounting sleeve (411) and an open spherical shell (412), the outer side of the laser receiver (44) is provided with threads and is screwed into the inner cavity of the mounting sleeve (411), the mounting sleeve (411) is in communication with the inner cavity of the outer shell (41), and a transparent glass plate is arranged at the connection; The surface of the laser receiver (44) is fixedly connected with a fixing cylinder (441), one end of the fixing cylinder (441) extends to the outer side of the mounting sleeve (411) and is fixedly connected with a knob (442), the knob (442) abuts against the end face of the mounting sleeve (411), and an annular sealing gasket is arranged therebetween, and a receiver cable (443) electrically connected with the laser receiver (44) is arranged in the inner cavity of the fixing cylinder (441); The outer side of the end of the laser emitter (43) is provided with a connecting ball (431), and the two are fixedly connected through a hollow connecting cylinder (432), the connecting ball (431) is rotatably arranged in the inner cavity of the open spherical shell (412) and is adapted thereto, a through hole (433) is formed in the middle of the connecting ball (431), the laser beam emitted by the laser emitter (43) enters the inner cavity of the outer shell (41) through the through hole (433), and a protective hose (434) is fixedly connected to the end face of the laser emitter (43), one end of the protective hose (434) is fixed to the surface of the outer shell (41).

2. The void condition monitoring instrument for the bridge concrete segment joint according to claim 1, characterized in that: The outer side of the mounting sleeve (411) is fixedly connected with a stop ring one (413), the outer side of the laser emitter (43) is fixedly connected with a stop ring two (435), the mounting rack (3) comprises two arc-shaped clamping members (31) which are symmetrically arranged and spliced into a circular ring, and two groups of mounting racks (3) are fixedly sleeved outside the mounting sleeve (411) and the laser emitter (43).

3. The void condition monitoring instrument for the bridge concrete segment joint according to claim 2, characterized in that: The inner wall of the arc-shaped holder (31) is fixedly connected with an arc-shaped pad (32), and the two ends of the arc-shaped holder (31) are fixedly connected with a connecting block (33) and a protruding block (331) respectively, and the connecting block (33) and the protruding block (331) are both provided with a connecting hole (332) on the surface, and the two arc-shaped holders (31) are fixedly connected through bolts.

4. The void condition monitoring instrument for the bridge concrete segment according to claim 3, characterized in that: One end of the connecting block (33) is fixedly connected with a connecting plate (34), the surface of the connecting plate (34) is provided with an elongated waist hole (35), the surface of the connecting plate (34) away from the connecting block (33) is fixedly connected with a shock pad (36), the surface of the mounting plate (2) is fixedly connected with a fixed stud (21) corresponding to the waist hole (35), the connecting plate (34) and the fixed stud (21) are fixedly connected through a nut, and a pad (22) is arranged between the nut and the connecting plate (34), and the two fixed studs (21) are connected together as a group through the pad (22).

5. The apparatus for monitoring the void condition of the bridge concrete segment joint according to claim 1, characterized in that: The outer shell (41) is provided with an opening on one side surface, and the opening is fixedly connected with a cover plate (415) for sealing.

6. The construction method of the void condition monitor for the bridge steel-concrete joint segment according to any one of claims 1-5, characterized in that: Specifically comprising the following steps: Step one, judge the distribution area of the steel-concrete joint segment void: Based on stress analysis, stress analysis is carried out on different parts of the steel-concrete joint segment, and the area with large normal stress is prone to void; Based on construction analysis, the construction process is not compacted, resulting in local concrete not being bonded together at the corners; Combined with the material properties, settlement and inclination of the steel-concrete joint segment to be tested, the finite element calculation analysis results of the steel-concrete joint segment are used to select the area with void for the following strain monitoring; Step two, determine the placement method of the surface-mounted strain gauge (1): According to the size, settlement and detection requirements of the steel-concrete joint segment, the area of the steel-concrete joint segment to be tested is divided; A column of surface-mounted strain gauges (1) is arranged on each divided area to monitor the parameters; Step three, collect parameter information and monitor the void position: All the data collected by the surface-mounted strain gauges (1) are summarized, and then the collected information data are processed to be visually displayed in the form of images; Once the strain value of a point changes suddenly, it can be determined that the void damage may occur at this point, and the void area range can be preliminarily determined by comparing the strain of the adjacent points; When more accurate positioning is required, the detection area where the possible void position is located is further divided into smaller detection areas in the same way, and the above steps one to three are repeated.

Images