Strain monitoring protection device for steel plate girder pushing construction

Abstract

The utility model discloses a kind of strain monitoring protective devices for steel plate beam incremental launching construction, belong to bridge construction monitoring device technical field.The device solves the strain gauge and its cable in steel plate beam incremental launching construction and is directly exposed to harsh environment and is vulnerable to mechanical collision, rain wash, vibration impact, dust invasion etc., leading to measurement error, equipment damage or signal interruption problem.Its technical scheme main point includes: rigid protective box is detachably connected to the surface of steel plate beam by fixed structure, box inner cavity is used to accommodate strain gauge and cable, cable is provided with waterproof cable plug and cable is reserved slack section in inner cavity;Buffer structure is arranged on the outer peripheral wall of rigid protective box, and transparent observation window is arranged on the surface of rigid protective box away from mounting opening;At the same time, inner cavity is filled with flexible sealing adhesive layer around strain gauge.The device is mainly used for effectively protecting strain monitoring equipment during incremental launching construction process, to ensure data acquisition accuracy and long-term reliability of equipment.

Description

Technical Field

[0001] This utility model belongs to the technical field of bridge construction monitoring devices, specifically relating to a strain monitoring and protection device for steel plate beam jacking construction. Background Technology

[0002] During the jacking construction of steel plate girders, strain monitoring of key components of the beam is necessary to obtain data on the structural stress state. Strain gauges and their connecting cables are typically directly exposed to the construction environment, making them susceptible to mechanical impacts, rain erosion, and dust accumulation, which can lead to measurement errors or equipment damage. Existing protective measures are mostly simple encapsulation or fixing methods, which are insufficient to provide long-term effective protection under complex construction conditions.

[0003] Due to the frequent movement and intense vibration of equipment during jacking operations, often accompanied by temporary welding and high-temperature work, the strain gauge installation area may be subjected to various external forces. Common protective covers only provide basic dust and splash protection, and their fixing methods often lack vibration and impact resistance, making them prone to displacement or detachment. In addition, cables often break due to structural deformation or external tension because they are not properly loosened, leading to signal interruption.

[0004] Another problem is that existing protective structures are often inconvenient for on-site inspection and maintenance. Construction workers cannot directly observe the condition of the internal strain gauges and must remove the protective structure before inspection can be carried out, which increases the workload and may damage the sensors or cables during disassembly and reassembly. At the same time, conventional protective devices often do not consider the heat insulation requirements in high-temperature working environments. When welding or thermal cutting operations are carried out nearby, radiant heat may cause the temperature of the strain gauge substrate to rise, affecting the accuracy of measurements or even causing the adhesive layer to fail.

[0005] Previous attempts to improve protection methods have encountered several difficulties. For example, using bolts to directly connect to the steel beam surface to enhance fixation strength can damage the beam coating and even the base material, and installation efficiency is low. If adhesive fixation is used, fatigue peeling of the adhesive layer is prone to occur under high vibration environments. In addition, achieving reasonable cable layout and protection in a limited space is also challenging. If the cable is fixed too tightly, it is easily stretched; if it is too loose, it is easily tangled or snagged. The lack of effective cushioning design also means that when the protective device is impacted, it not only fails to protect the sensor, but may also deform and crush internal components.

[0006] Therefore, there is an urgent need for a strain monitoring and protection device suitable for the harsh working conditions of jacking construction. Summary of the Invention

[0007] This utility model provides a strain monitoring and protection device for steel plate beam jacking construction. It can be quickly installed and disassembled by magnetic adsorption, effectively resisting vibration and impact during construction. The flexible sealing layer inside the protective box can buffer vibration and protect the strain gauge. The reserved cable slack section and cable fixing structure can prevent the cable from being pulled apart. The transparent observation window facilitates direct observation of the internal condition. At the same time, the heat insulation lining can reduce the impact of high temperature operation on measurement, thereby ensuring the reliability and durability of strain monitoring in harsh construction environments.

[0008] To achieve these objectives and other advantages of this utility model, a strain monitoring and protection device for steel plate beam jacking construction is provided, comprising:

[0009] A rigid protective box having an installation opening for connecting to the surface of a steel plate beam;

[0010] A fixing structure is provided on the rigid protective box near the mounting opening for detachably connecting the rigid protective box to the surface of the steel plate beam; wherein, the inner cavity of the rigid protective box is used to accommodate the strain gauge and its cable, the side wall of the rigid protective box is provided with a cable hole for the cable to pass through, a waterproof cable plug is provided at the cable hole, and the cable has a slack section reserved in the inner cavity;

[0011] A buffer structure is provided on the outer peripheral wall of the rigid protective box;

[0012] A transparent observation window is disposed on the surface of the rigid protective box away from the mounting opening;

[0013] The inner cavity of the rigid protective box is filled with a flexible sealant layer around the strain gauge.

[0014] Preferably, the fixing structure includes multiple magnetic chucks, which are cup-shaped permanent magnet chucks that are embedded and fixed inside the rigid protective box wall by countersunk screws, and whose adsorption working surface protrudes from the plane of the mounting opening; the multiple magnetic chucks are symmetrically distributed in a matrix around the mounting opening of the rigid protective box, and the total adsorption force provided by the magnetic chucks is greater than three times the maximum expected horizontal impact force of the entire protective device.

[0015] Preferably, a flexible wear-resistant pad is placed between the magnetic chuck and the surface of the steel plate beam. The flexible wear-resistant pad is made of polyurethane or synthetic rubber material, and its Shore A hardness is between 60° and 90°.

[0016] The flexible wear-resistant pad is bonded and fixed to the adsorption working surface of the magnetic chuck by a high-strength adhesive layer, and its planar dimensions are larger than the adsorption working surface of the magnetic chuck.

[0017] The free surface of the flexible wear-resistant pad is either a smooth plane or has micro-patterns that increase friction.

[0018] Preferably, the slack section of the cable is fixed to the inner wall of the rigid protective box by a cable clip, which is a nylon cable tie, a metal spiral wound tube clamp, or a plastic cable clip embedded in the inner wall of the rigid protective box.

[0019] The number of the wire clips is multiple, and at least the beginning, end and middle of the slack section are constrained and fixed, and the slack section is coiled into a ring with a diameter not less than 5 times the diameter of the cable.

[0020] The contact surface between the cable and the wire is a smooth surface or is covered with a flexible sheath.

[0021] Preferably, the buffer structure is a strip-shaped buffer body surrounding the outer peripheral wall of the rigid protective box, which is integrally molded from polyurethane or nitrile rubber material with a Shore A hardness of 50° to 70°; the cross-section of the strip-shaped buffer body is an outwardly convex arc or trapezoidal shape, and its outermost convex point protrudes outward by 10mm to 20mm relative to the outer peripheral wall of the rigid protective box.

[0022] The strip-shaped buffer body is connected to the T-shaped groove on the outer peripheral wall of the rigid protective box by an interference fit through the T-shaped ribs pre-embedded on its inner side.

[0023] The outer surface of the strip-shaped buffer is covered with a wear-resistant coating layer of reflective or fluorescent material.

[0024] Preferably, the rigid protective box is made of metal material, and its inner wall is fitted with a heat insulation lining. The heat insulation lining is a ceramic fiber blanket, glass fiber reinforced calcium silicate board or aerogel felt, with a thickness of 3 mm to 10 mm and a thermal conductivity of less than 0.05 W / (m·K).

[0025] The heat insulation lining is bonded and fixed to the inner wall of the rigid protective box by a high-temperature resistant adhesive, and its coverage area includes at least the inner top wall opposite the transparent observation window and the upper part of the side wall affected by heat radiation.

[0026] The outer surface of the heat insulation liner is covered with an aluminum foil reflective layer, which is adhered and fixed between the heat insulation liner and the inner wall of the rigid protective box, or covered on the surface of the heat insulation liner facing the inner cavity.

[0027] Preferably, the transparent observation window is sealed to the rigid protective box body by a sealing strip and fastened by quick-release bolts.

[0028] Preferably, the cross-section of the rigid protective box is a streamlined ellipse.

[0029] Preferably, the flexible sealant layer is a silicone sealant or a polyurethane sealant with a Shore A hardness of 20° to 40°, an elastic recovery rate of more than 90%, and a filling height in the inner cavity of not less than 1.5 times the thickness of the strain gauge.

[0030] Preferably, the transparent observation window is made of polycarbonate or tempered glass, with a thickness of 5mm-12mm, a light transmittance of not less than 85%, and its outer surface is coated with an anti-scratch coating.

[0031] This utility model has at least the following beneficial effects:

[0032] First, this utility model achieves multiple layers of protection for strain gauges and cables through a comprehensive design including a rigid protective box, a fixing structure, a buffer structure, a transparent observation window, and an internal flexible sealing layer. It possesses excellent impact resistance, vibration resistance, dust and water resistance, while also facilitating observation and maintenance, significantly improving the reliability and service life of the monitoring equipment. This utility model employs a matrix-distributed cup-shaped permanent magnet chuck for embedded fixing, ensuring both convenient installation and detachment. Its high-adhesion design effectively resists horizontal impacts and vibrations during construction, preventing displacement or detachment of the protective device. The use of flexible wear-resistant gaskets reduces direct contact between the magnetic chuck and the steel beam surface, protecting the steel beam coating and absorbing some vibration through material elasticity, thus improving the stability and adaptability of the fixing.

[0033] Secondly, this utility model effectively prevents cable breakage caused by construction vibration or external pulling by using multi-point fixing and a ring-shaped coiling design for the slack section of the cable with wire clips, ensuring the continuity and stability of signal transmission. The strip-shaped buffer absorbs and disperses external impact force through its convex structure and elastic material, reducing vibration transmitted to the rigid protective box. At the same time, the reflective or fluorescent coating layer improves the visibility and safety of the device in low-light environments. The combination of the heat insulation liner and the aluminum foil reflective layer effectively blocks external high-temperature heat radiation, preventing the strain gauge from causing measurement errors or adhesive layer failure due to temperature rise, thus improving the monitoring accuracy under high-temperature conditions. The combination of the sealing strip and quick-release bolts ensures the sealing reliability of the observation window and facilitates quick disassembly and assembly for inspection or maintenance, improving construction efficiency and equipment availability. The streamlined elliptical cross-section reduces wind resistance and the probability of collision during construction of the rigid protective box, lowering the risk of accidental impact due to its protruding shape. The flexible sealing layer not only fixes and buffers the strain gauges but also effectively prevents moisture and dust from entering, improving the sealing and stability of the internal environment. The highly transparent and scratch-resistant observation window material ensures clear visibility over long-term use, reduces maintenance needs due to surface damage, and enhances the overall durability of the device.

[0034] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0035] Figure 1 This is a side view of the strain monitoring and protection device for steel plate beam jacking construction according to this utility model. Detailed Implementation

[0036] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0037] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0038] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials described are commercially available. In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0039] like Figure 1 As shown, this utility model embodiment provides a strain monitoring and protection device for steel plate beam jacking construction, comprising:

[0040] Rigid protective box 1 has an installation opening 3 for connecting to the surface of steel plate beam 4; the cross-section of the rigid protective box 1 is a streamlined elliptical shape;

[0041] A fixed structure is provided on the rigid protective box 1 near the mounting opening 3 for detachably connecting the rigid protective box 1 to the surface of the steel plate beam 4; wherein, the inner cavity of the rigid protective box 1 is used to accommodate the strain gauge 5 and its cable, and a cable hole 7 is provided on the side wall of the rigid protective box 1 for the cable to pass through, a waterproof cable plug 10 is provided at the cable hole 7, and the cable has a slack section reserved in the inner cavity;

[0042] A buffer structure 6 is disposed on the outer peripheral wall of the rigid protective box 1;

[0043] A transparent observation window 8 is disposed on the surface of the rigid protective box 1 away from the mounting opening 3;

[0044] The inner cavity of the rigid protective box 1 is filled with a flexible sealant layer 9 around the strain gauge 5.

[0045] In the above embodiment, the rigid protective box 1, as the main structure of the entire device, is typically made of metal and possesses sufficient rigidity and strength to withstand external impacts and vibrations. It has an installation opening 3, which allows the rigid protective box 1 to fit tightly against the surface of the steel beam 4, forming a closed inner cavity. The edges of the installation opening 3 are usually chamfered or sealed to prevent rainwater and dust from entering. The inner cavity of the rigid protective box 1 is used to accommodate the strain gauges 5 and their connecting cables. Its dimensions need to be designed according to the actual size of the strain gauges 5 and the number of cables, generally with appropriate margins to facilitate wiring and later maintenance. The overall structure of the rigid protective box 1 can be designed as streamlined or low-profile according to the actual construction environment to reduce the risk of collisions with other equipment or structures during the jacking process.

[0046] The fixing structure is located on the side of the rigid protective box 1 near the mounting opening 3, used to achieve a detachable connection between the rigid protective box 1 and the steel plate beam 4. Magnetic adsorption is preferred, for example, using multiple cup-shaped permanent magnet chucks symmetrically arranged in a matrix around the mounting opening 3. These chucks are embedded into the box wall of the rigid protective box 1 using countersunk screws, with the adsorption working surface slightly protruding from the mounting plane to ensure full contact with the surface of the steel plate beam 4. The total adsorption force of the magnetic chucks 2 needs to be calculated and should generally be more than three times the expected maximum horizontal impact force to prevent displacement or detachment under vibration or instantaneous impact. This fixing method not only allows for quick installation without drilling or welding, protecting the beam coating and structural integrity, but also facilitates rapid removal and reuse after monitoring.

[0047] A cable hole 7 is made on the side wall of the rigid protective box 1 to supply the cable for the transformer 5. A waterproof cable plug 10 is installed at the cable hole 7. This cable plug is usually made of rubber or silicone material, which has a certain degree of compressibility and elasticity, and can tightly wrap the cable and prevent moisture from seeping in along the gaps. A slack section is reserved in the inner cavity of the cable. This slack section is fixed to the inner wall of the box by a cable clip 12 (such as nylon cable ties, plastic cable buckles, etc.) and stored in a ring-shaped coil. The diameter of the ring is generally not less than five times the diameter of the cable itself to avoid damage to the wire core due to excessive bending. This design allows the slack section to release tension when the beam undergoes slight deformation or the cable is pulled externally, preventing the cable from being pulled off directly, thereby ensuring the continuity and stability of signal transmission.

[0048] The buffer structure 6 is located on the outer peripheral wall of the rigid protective box 1. It is typically a strip-shaped buffer encircling the box, made of a material with elasticity and wear resistance, such as polyurethane or nitrile rubber. Its cross-section can be designed as a convex arc or trapezoid, with the outermost protrusion extending approximately 10-20 mm beyond the outer wall of the box. This allows it to first contact the impacting object upon impact and absorb energy through material deformation, reducing the impact force transmitted into the box. The strip-shaped buffer can be installed with an interference fit between pre-embedded T-shaped ribs and T-shaped slots on the box, ensuring convenient assembly and disassembly and a secure connection. Furthermore, the outer surface of the strip-shaped buffer can be covered with reflective or fluorescent materials to enhance visibility in low-light environments and improve construction safety.

[0049] A transparent observation window 8 is located on the top or side of the rigid protective box 1. It is made of a highly transparent and impact-resistant material, such as polycarbonate or tempered glass, and is sealed to the box body via a sealing strip 13 and quick-release bolts. This ensures waterproofing and dustproofing while facilitating opening and closing for internal inspection or maintenance. Inside the rigid protective box 1, the strain gauge 5 is surrounded by a flexible sealing layer 9. This flexible sealing layer 9 is typically made of silicone or polyurethane sealant, offering good elasticity, waterproofing, and cushioning properties. The filling height of the sealing layer is generally no less than 1.5 times the thickness of the strain gauge 5, effectively fixing the sensor, dispersing vibration energy, and preventing moisture and dust from entering the sensitive area, thereby improving measurement reliability and equipment durability.

[0050] In summary, this embodiment achieves rapid installation and reliable fixation through the combination of a rigid protective box 1 and a magnetic fixing structure, avoiding damage to the steel plate beam 4 structure. The cable slack section and waterproof design significantly improve the cable's survivability in complex construction environments. The buffer structure 6 effectively absorbs and disperses external impacts, protecting internal components. The transparent observation window 8 facilitates real-time monitoring of sensor status, reducing unnecessary disassembly and assembly. The internal flexible sealing layer 9 further enhances waterproof, vibration-damping, and sealing performance. Compared with existing technologies, this device exhibits significantly higher adaptability and reliability under harsh construction conditions, effectively extending the service life of monitoring equipment and improving the accuracy of data acquisition.

[0051] In one specific embodiment, the fixing structure includes multiple magnetic chucks 2, each of which is a cup-shaped permanent magnet chuck. It is fixed to the inner wall of the rigid protective box 1 by countersunk screws, and its adsorption working surface protrudes from the plane of the mounting opening 3. The multiple magnetic chucks 2 are symmetrically distributed in a matrix around the mounting opening 3 of the rigid protective box 1. The total adsorption force provided by the magnetic chucks 2 is greater than three times the maximum expected horizontal impact force of the entire protective device.

[0052] In the above embodiment, the fixing structure includes multiple magnetic chucks 2, which are cup-shaped permanent magnet chucks. These cup-shaped permanent magnet chucks are typically made of high-performance rare-earth permanent magnet materials such as neodymium iron boron. Their internal magnetic circuit design generates a strong magnetic field on the open magnetic pole surface, thereby forming a stable adsorption force on the steel surface. These magnetic chucks 2 are embedded and fixed within the rigid protective box 1 using countersunk screws. This installation method not only integrates the magnetic chuck 2 structure into the box body, improving the overall structural consistency, but also avoids interference or damage that might be caused by exposed screws. The selection of countersunk screws typically considers their mechanical strength and corrosion resistance; for example, stainless steel can be used, with specifications ranging from M4 to M8, to accommodate the installation requirements of magnetic chucks 2 of different sizes. The adsorption working surface of the magnetic chuck 2 is designed to slightly protrude from the plane of the mounting opening 3. This feature ensures that when in contact with the surface of the steel plate beam 4, the magnetic chuck 2 can preferentially contact and establish an effective magnetic path, avoiding a decrease in adsorption force due to deformation of the rigid protective box 1 itself or uneven surface. Multiple magnetic suction cups 2 are symmetrically arranged in a matrix around the mounting opening 3, such as in a 2×2, 3×3, or other symmetrical arrays. This arrangement helps to evenly distribute the adsorption force and improves the device's resistance to overturning under asymmetrical loads. In a 3×3 matrix layout, the mounting opening 3 occupies the central position, so eight magnetic suction cups 2 are actually used. The total adsorption force provided by the magnetic suction cups 2 must be greater than three times the maximum expected horizontal impact force on the entire protective device. For example, if the expected maximum impact force is 500 Newtons, the total adsorption force should be no less than 1500 Newtons. This safety factor ensures that the protective device remains firmly attached under vibrations, instantaneous impacts, or wind loads commonly encountered during construction, greatly reducing the risk of detachment.

[0053] In this fixed structure, the magnetic chuck 2, as the core component directly performing the adsorption function, features an embedded installation that ensures structural compactness while optimizing the contact with the steel beam 4 surface through its protruding working surface design. The matrix-symmetric arrangement enhances system stability from a mechanical distribution perspective. The required ratio between the total adsorption force and the impact force represents a conservative design strategy from an engineering safety standpoint, ensuring reliable fixation even under extreme conditions. These technical features work synergistically to form a magnetic fixing system that is both easy to assemble and disassemble and resistant to strong vibrations and impacts.

[0054] In one specific embodiment, a flexible wear-resistant pad 11 is placed between the magnetic chuck 2 and the surface of the steel plate beam 4. The flexible wear-resistant pad 11 is made of polyurethane or synthetic rubber material, and its Shore A hardness is between 60° and 90°.

[0055] The flexible wear-resistant pad 11 pieces are bonded and fixed to the adsorption working surface of the magnetic chuck 2 by a high-strength adhesive layer, and its planar size is larger than the adsorption working surface of the magnetic chuck 2.

[0056] The free surface of the 11 flexible wear-resistant pads is either a smooth plane or has micro-patterns that increase friction.

[0057] In the above embodiment, a flexible wear-resistant pad 11 is added between the magnetic chuck 2 and the surface of the steel plate beam 4. This flexible wear-resistant pad 11 is made of a high-molecular elastic material such as polyurethane or synthetic rubber, and its core function is to act as a soft intermediary without weakening the magnetic adsorption force. When selecting materials, Shore A hardness is a key parameter, typically chosen between 60° and 90°, with 70° or 80° being common options. Lower hardness materials provide better fit and cushioning, while higher hardness materials are more wear-resistant and provide better support. This hardness range ensures that the pad has sufficient elasticity to adapt to the microscopic unevenness of the steel plate surface, thereby increasing the effective contact area, while maintaining the necessary compressive strength and durability to avoid excessive deformation under long-term pressure. Its working principle is to use the elastic deformation of the material to fill the tiny gaps that may exist between the working surface of the magnetic chuck 2 and the surface of the steel beam, and to transform the contact pressure that may have been concentrated at a few high points into a more evenly distributed surface pressure. This not only improves the stability of adsorption, but also absorbs some of the high-frequency vibration energy through the damping characteristics of the material.

[0058] The 11 flexible wear-resistant pads are firmly bonded to the magnetic chuck 2's adsorption surface using a high-strength adhesive layer. This adhesive is typically an epoxy resin or acrylic high-performance structural adhesive, with a shear strength far exceeding that of the flexible wear-resistant pad material itself. This ensures that under shear force, failure occurs within the flexible wear-resistant pads rather than at the adhesive interface. The planar dimensions of the flexible wear-resistant pads are intentionally designed to be larger than the magnetic chuck 2's adsorption surface, meaning their edges extend beyond the chuck's working surface contour. This "oversized" design offers multiple benefits: it increases the actual contact area with the steel beam surface, further dispersing pressure; it covers and protects the potentially sharp edges of the magnetic chuck 2, preventing scratches to the beam's anti-corrosion coating; and most importantly, it forms a continuous sealing ring that effectively prevents corrosive media such as mud and moisture from intruding and accumulating at the chuck-steel beam interface, preventing electrochemical corrosion or freeze-thaw adhesion.

[0059] The free surface of the 11 flexible wear-resistant pads, which is the side that directly contacts the steel plate beam 4, has two design orientations depending on the application requirements. One is to process it into a smooth plane, which minimizes frictional resistance, allowing the protective device to be easily slid off when adjustment or disassembly is needed, making it particularly suitable for scenarios requiring frequent movement. The other is to design micro-patterns on the surface to increase friction. These patterns can be tiny dot-like protrusions, cross-hatching, or other geometric patterns, with a depth on the order of a few tenths of a millimeter. This micro-patterned surface increases the static friction with the steel beam surface, similar to a tire tread, and can more effectively resist horizontal slippage, making it particularly suitable for conditions with severe vibration or potentially large lateral forces. These two surface treatment processes, combined with the elasticity of the 11 flexible wear-resistant pads themselves, allow for an optimized choice between "easy disassembly" and "anti-slip" based on the specific construction environment.

[0060] In one specific embodiment, the slack section of the cable is fixed to the inner wall of the rigid protective box 1 by a cable clip 12, which is a nylon cable tie, a metal spiral tube clamp, or a plastic cable buckle pre-embedded in the inner wall of the rigid protective box 1.

[0061] The number of the wire clips 12 is multiple, and at least the beginning, end and middle of the slack section are constrained and fixed, and the slack section is coiled into a ring with a diameter not less than 5 times the diameter of the cable.

[0062] The contact surface between the cable clip 12 and the cable is a smooth surface or is covered with a flexible sheath.

[0063] In the above embodiment, cable clips 12 are used to orderly fix the slack sections of the cable to the inner wall of the rigid protective box 1. As a key fastener, the cable clips 12 offer a variety of options to suit different needs: nylon cable ties are widely used due to their low cost, ease of installation, and good insulation; metal spiral wound clamps offer higher mechanical strength and high-temperature resistance, suitable for harsher environments; and plastic cable clips pre-embedded in the inner wall of the protective box are a more integrated solution, embedded during box manufacturing to avoid sealing problems that may arise during later installation, providing a permanent fixing point. The specific selection of these cable clips 12 can be determined based on the number and thickness of the cables and the expected vibration intensity. For example, nylon cable ties may be sufficient for a single thin cable, while for a bundle of cables or an environment with strong vibration, a more robust metal clip or pre-embedded cable clip may be preferred. In practice, the construction workers will first leave a slack section in the box for the cable led out from the strain gauge 5, which is much longer than the length required for direct lead-out. Then, they will choose a suitable location on the inner wall of the box, such as the side wall or a corner that will not affect the filling of the sealant, to arrange these cable clips 12.

[0064] To ensure that the slack section effectively absorbs tension under any external force and does not directly transmit the force to the fragile strain gauge 5 weld joints, the number of wire clamps 12 cannot be singular; multiple clamps are required to implement at least three-point constraint fixation at the beginning, end, and middle. Specifically, after the cable is led out from the strain gauge 5, it is first loosely fixed at the beginning with a wire clamp 12 to prevent it from retracting. Then, the construction personnel coil the cable into a loop, fixing it with wire clamps 12 at the end of the loop and near the bend apex (middle) of the loop. This multi-point constraint method divides a continuous cable into several small segments. Even if a small displacement occurs at a fixed point, its effect will be absorbed by the adjacent slack section, thus avoiding stress concentration. More importantly, this scheme explicitly requires that the slack cable be coiled into a loop, and the diameter of this loop has a lower limit, namely, not less than 5 times the diameter of the cable itself. For example, for a cable with an outer diameter of 4 mm, the diameter of the loop should be at least 20 mm. This size requirement is based on the engineering principle of cable bending radius, and its purpose is to prevent fatigue damage or signal degradation of the internal metal conductors and shielding layers of the cable due to excessive bending curvature.

[0065] To further enhance the comprehensiveness of protection, attention was also paid to the microscopic interface between the cable clamp 12 and the cable contact surface. The clamping surface of the cable clamp 12 is designed as a smooth surface, or a flexible sheath made of soft rubber or silicone is fitted at the clamping point. The smooth surface reduces friction with the cable sheath, allowing for slight slippage of the cable within the fixing point to redistribute stress; while the flexible sheath provides a buffer, increasing friction to prevent cable slippage and dispersing the clamping force of the cable clamp 12 on the cable sheath, preventing crushing or abrasion of the cable insulation layer. This detailed treatment, combined with the aforementioned annular coiling and multi-point fixing, constitutes a multi-layered protection mechanism: the annular coiling provides macroscopic length margin, multi-point fixing achieves segmented stress management, and the optimized contact interface ensures that the fixing process itself does not damage the cable.

[0066] In one specific embodiment, the buffer structure 6 is a strip-shaped buffer body arranged around the outer peripheral wall of the rigid protective box 1, which is integrally molded from polyurethane or nitrile rubber material with a Shore A hardness of 50° to 70°; the cross-section of the strip buffer body is an outwardly convex arc or trapezoidal shape, and its outermost convex point protrudes outward by 10mm to 20mm relative to the outer peripheral wall of the rigid protective box 1.

[0067] The strip-shaped buffer body is connected to the T-shaped groove on the outer peripheral wall of the rigid protective box 1 by an interference fit through the T-shaped ribs pre-embedded on its inner side.

[0068] The outer surface of the strip-shaped buffer is covered with a wear-resistant coating layer of reflective or fluorescent material.

[0069] In the above embodiment, the buffer structure 6 is a strip-shaped buffer body surrounding the outer peripheral wall of the rigid protective box 1. This strip-shaped buffer body is integrally molded from a polymer material with excellent elasticity and wear resistance, such as polyurethane or nitrile rubber. Material selection is crucial; its Shore A hardness is limited to between 50° and 70°, with 55° or 65° being common values ​​in practice. This hardness range ensures that the material possesses moderate rigidity to support its shape while maintaining sufficient flexibility for effective energy absorption. When an external object impacts the protective box, materials within this hardness range can absorb and disperse most of the impact energy through their elastic deformation, rather than directly transferring the energy to the fragile internal monitoring components. The cross-section of the strip-shaped buffer body is designed as a convex arc or trapezoid, with the distance from its outermost convex point relative to the outer peripheral wall of the protective box controlled between 10mm and 20mm, such as 12mm, 15mm, or 18mm. This convex design makes the strip-shaped buffer the "first line of defense" of the entire device. Before any collision occurs, the protruding strip-shaped buffer will contact the impactor before the rigid box, and extend the impact time by undergoing controllable compression deformation first, thereby significantly reducing the instantaneous impact acceleration.

[0070] The connection between the strip-shaped buffer and the rigid protective box 1 needs to balance strength and convenience. T-shaped ribs are pre-embedded on the inner side of the strip-shaped buffer, while precisely matching T-shaped slots are formed on the outer peripheral wall of the rigid protective box 1. During installation, the initial connection is achieved by aligning the T-shaped ribs at a specific angle and pressing them into the T-shaped slots. The design requires an interference fit, meaning the ribs are slightly larger than the slots, which generates a certain assembly force, preventing the buffer from loosening under normal use. This connection method avoids the use of adhesives or screws, preventing failure due to adhesive aging or screw corrosion, and greatly facilitating on-site replacement of the buffer after wear; it can be removed simply by applying axial force.

[0071] To further enhance the functionality and safety of the device, the outer surface of the strip-shaped buffer is also covered with a wear-resistant coating. This coating is made of reflective or fluorescent materials, such as microprism reflective film or long-lasting fluorescent coating. In low-light conditions at the construction site, such as at dusk, night, or in poorly lit indoor environments, this coating can reflect light when illuminated by vehicle headlights or other light sources, or emit a soft fluorescence, thereby improving the visual visibility of the protective device. This not only aids in equipment management but also effectively warns surrounding machinery and personnel, preventing accidental collisions.

[0072] In one specific embodiment, the rigid protective box 1 is made of metal material, and its inner wall is fitted with a heat insulation lining. The heat insulation lining is a ceramic fiber blanket, a glass fiber reinforced calcium silicate board or an aerogel felt, with a thickness of 3 mm to 10 mm and a thermal conductivity of less than 0.05 W / (m·K).

[0073] The heat insulation lining is bonded and fixed to the inner wall of the rigid protective box 1 by a high-temperature resistant adhesive, and its coverage area includes at least the inner top wall opposite the transparent observation window 8 and the upper part of the side wall affected by heat radiation.

[0074] The outer surface of the heat insulation liner is covered with an aluminum foil reflective layer, which is adhered and fixed between the heat insulation liner and the inner wall of the rigid protective box 1, or covered on the surface of the heat insulation liner facing the inner cavity.

[0075] In the above embodiment, a high-performance thermal insulation liner is bonded to the metal inner wall of the rigid protective box 1. The thermal insulation liner is made of materials with extremely low thermal conductivity, such as ceramic fiber blankets, glass fiber reinforced calcium silicate boards, or aerogel felt. These materials share the characteristic of having a large number of tiny static air pores, which greatly impede heat conduction. Their thermal conductivity is strictly limited to below 0.05 W / (m·K), preferably 0.03 W / (m·K) or 0.04 W / (m·K). The thickness of the thermal insulation liner is designed to be between 3 mm and 10 mm, for example, choosing a thickness of 5 mm or 8 mm, to achieve a balance between thermal insulation performance and internal space occupation. A liner that is too thin will have insufficient thermal insulation, while a liner that is too thick will excessively compress the space accommodating the strain gauge 5 and the cables. The thermal insulation liner is firmly bonded to the inner wall of the rigid protective box 1 using a high-temperature resistant adhesive, such as a silicone resin adhesive. Its coverage area is not the entire inner wall, but is specifically designed to include at least the inner top wall directly opposite the transparent observation window 8 and the upper part of the side wall that is susceptible to radiation from external heat sources (such as welding and thermal cutting). This focused protection layout ensures that heat radiation from above or the upper sides is effectively blocked.

[0076] An aluminum foil reflective layer was added to the thermal insulation liner. Aluminum foil has extremely low thermal emissivity and high reflectivity. Its working principle is that when infrared radiation from an external heat source reaches the rigid protective box 1, the aluminum foil reflective layer directly reflects most of the radiant energy back, rather than absorbing it and converting it into heat that is then conducted into the inner cavity. The arrangement of the aluminum foil reflective layer offers two flexible options: one is to adhere it between the thermal insulation liner and the inner wall of the rigid protective box 1; the other is to directly cover the surface of the thermal insulation liner facing the inner cavity. The former method protects the aluminum foil from mechanical damage, while the latter maximizes its reflective effect. The aluminum foil reflective layer and the thermal insulation liner work together to form a dual thermal insulation mechanism of "reflection + blocking": the aluminum foil reflective layer is mainly responsible for reflecting radiant heat, while the thermal insulation liner mainly inhibits the remaining heat conduction and convection. Together, they constitute a highly efficient thermal barrier.

[0077] During the actual installation process, the construction workers first need to cut the appropriate heat insulation lining and aluminum foil reflective layer according to the size and shape of the inner wall of the rigid protective box 1. If the aluminum foil reflective layer is in the middle, a high-temperature resistant adhesive will be used to attach the aluminum foil reflective layer to the designated area of ​​the inner wall of the box, and then the heat insulation lining will be attached on top of the aluminum foil reflective layer. If the aluminum foil reflective layer is on the inner surface, the heat insulation lining will be attached first, and then the aluminum foil reflective layer will be covered on its surface. Ensuring a smooth and bubble-free adhesion is key to guaranteeing the heat insulation effect. After the adhesion is completed, the inner wall surface changes from a highly thermally conductive metal to a composite wall surface with excellent heat insulation and reflection functions. When there is an external heat source, its heat radiation is first largely reflected by the aluminum foil layer, and the small amount of heat that penetrates is greatly slowed down by the heat insulation lining, allowing the interior of the protective box to maintain a relatively low and stable temperature environment for a considerable period of time.

[0078] In one specific embodiment, the transparent observation window 8 is sealed to the rigid protective box 1 by a sealing strip 13 and fastened by quick-release bolts.

[0079] In the above embodiment, the transparent observation window 8 and the rigid protective box 1 are sealed together by a sealing strip 13. The sealing strip 13 is typically made of a material with good elasticity and durability, such as EPDM rubber or silicone rubber, and its cross-sectional shape can be circular, square, or D-shaped. This sealing strip 13 is placed in a pre-machined sealing groove at the edge of the transparent observation window 8 or the opening of the box. When the transparent observation window 8 is pressed, the sealing strip 13 undergoes elastic deformation, filling all the microscopic gaps between the glass or polycarbonate plate of the transparent observation window 8 and the metal box, forming a continuous, gapless sealing ring. This effectively prevents external moisture, dust, and other contaminants from intruding into the rigid protective box 1, providing a dry and clean environment for the internal strain gauges 5 and cables. The hardness, compressibility, and other parameters of the sealing strip 13 material need to be selected to ensure sufficient sealing force is maintained under long-term use and temperature changes.

[0080] To facilitate easy opening of the transparent observation window 8 for inspection or maintenance, quick-release bolts are used as fasteners. Unlike ordinary bolts that require tools to tighten one by one, quick-release bolts typically include wing bolts with butterfly handles and knurled head bolts with flanged handles, allowing the operator to quickly tighten and loosen them by hand. These bolts are usually made of stainless steel for corrosion resistance, and their thread specifications may be smaller, such as M4 or M6, to ensure sufficient tightening force while minimizing the footprint on the housing structure. The number and placement of the quick-release bolts are carefully designed, for example, symmetrically distributed at the four corners or along the edges of the rectangular transparent observation window 8, to ensure uniform pressure applied to the sealing strip 13 and prevent seal failure due to insufficient local pressure. When closing the transparent observation window 8, the operator simply tightens these quick-release bolts by hand, sequentially or diagonally, until noticeable resistance is felt, indicating that the sealing strip 13 has been compressed to the predetermined degree, and the installation is complete.

[0081] The sealing strip 13 and the quick-release bolt work together to form a reliable and convenient sealing and fastening solution. The sealing strip 13 provides the core sealing function, while the quick-release bolt provides an easy-to-operate, tool-free tightening mechanism. Their collaborative operation can be described as follows: when the operator tightens the quick-release bolt by hand, the clamping force generated by the bolt presses the transparent viewing window 8 evenly against the housing, thereby compressing the sealing strip 13. The reverse elastic force generated by the compressed sealing strip 13 ensures the tightness of the sealing interface and also provides locking force for the bolt, preventing it from loosening due to vibration. When opening is required, the quick-release bolt is loosened in the opposite direction, and the rebound of the sealing strip 13 helps to open the transparent viewing window 8, making it easy to remove. This design cleverly combines a static sealing element with a dynamic quick-locking mechanism.

[0082] In one specific embodiment, the flexible sealant layer 9 is a silicone sealant or a polyurethane sealant with a Shore A hardness of 20° to 40°, an elastic recovery rate of more than 90%, and its filling height in the inner cavity is not less than 1.5 times the thickness of the strain gauge 5.

[0083] In the above embodiment, the material for the 9-layer flexible sealant was determined to be either silicone sealant or polyurethane sealant. These two materials were carefully selected: silicone sealant is known for its excellent high and low temperature resistance, long-term elasticity, and chemical stability; while polyurethane sealant typically has higher mechanical strength and abrasion resistance. When selecting a specific product, its Shore A hardness is a core mechanical indicator, limited to between 20° and 40°, with options such as 25°, 30°, or 35° being feasible. This hardness range is crucial, ensuring that the cured sealant layer is in a very soft state. This softness allows the sealant layer to act as an efficient buffer; when external impacts or vibrations are transmitted to the protective housing, the sealant layer can absorb and disperse this mechanical energy through its own elastic deformation, rather than directly transferring it to the fragile strain gauge 5. Simultaneously, this moderate hardness also ensures that the sealant layer will not generate excessive static stress on the strain gauge 5 during long-term use.

[0084] To ensure the durability of this cushioning performance, the elastic recovery rate of the nine layers of flexible sealant is further required to be greater than 90%. This allows the sealant to recover most of its original shape after repeated or prolonged compression and stretching deformation, with only minimal permanent deformation when the external force is removed. For example, a sealant with an elastic recovery rate of 95% can almost completely rebound after being deformed. This characteristic is essential for protective devices that withstand continuous vibrations and possible accidental impacts during construction, ensuring that the sealant layer can continuously provide cushioning without plastic deformation, compression, or failure due to fatigue. In actual construction, the operator needs to mix the selected two-component or one-component sealant evenly according to the ratio and inject it in liquid or paste form into the inner cavity of the protective box where the strain gauge 5 and the cable have been fixed.

[0085] Regarding the geometry of the sealant, a clear lower limit is specified: the sealant height must be no less than 1.5 times the thickness of strain gauge 5. For example, if strain gauge 5 itself is 1 mm thick, the sealant height above it should be at least 1.5 mm; for thicker strain gauges 5, this should be increased proportionally. This requirement ensures that the sealant layer has sufficient volume to form an effective three-dimensional enclosure. In principle, a thin sealant layer has limited buffering effect and may lose contact with the top of the component when the sealant shrinks due to temperature changes, creating gaps. A sealant layer with a thickness of 1.5 times or more provides sufficient enclosure and support for strain gauge 5 from all directions, ensuring effective buffering when subjected to forces from different directions. Simultaneously, sufficient sealant volume also means a longer sealing path can be formed, greatly enhancing the ability to prevent the penetration of moisture, humidity, and dust.

[0086] In one specific embodiment, the transparent observation window 8 is made of polycarbonate or tempered glass, with a thickness of 5mm-12mm, a light transmittance of not less than 85%, and its outer surface is coated with an anti-scratch coating.

[0087] In the above embodiments, the transparent observation window 8 is specified to be made of either polycarbonate or tempered glass. The choice of these two materials is based on their different advantages to adapt to diverse construction environments. Polycarbonate is known for its excellent impact resistance and can effectively resist the impact of flying objects; while tempered glass has higher surface hardness and scratch resistance, and its optical distortion is smaller. The thickness of the transparent observation window 8 is limited to between 5 mm and 12 mm, with 8 mm or 10 mm being common choices. This thickness range was determined after comprehensively balancing mechanical strength, weight, and cost: sufficient thickness ensures that the observation window has the necessary structural rigidity to withstand a certain amount of external pressure and impact, preventing loss of sealing due to deformation or breakage; at the same time, this thickness does not excessively increase the overall weight and manufacturing cost of the protective box. During installation, this transparent panel of the predetermined thickness is precisely embedded into the opening of the box, serving as a window for observing the internal conditions.

[0088] To ensure the effectiveness of the observation function, the light transmittance of the observation window is specified to be no less than 85%. This indicator, such as 88% or 90%, ensures that sufficient light intensity can pass through the observation window, allowing construction personnel to clearly visually inspect the condition of the internal strain gauges 5, the connection status of cables, and whether there are any abnormalities in the sealant without opening the protective box. Achieving high light transmittance relies on the high purity of the material itself and the optical-grade polishing treatment of the plate surface, minimizing the absorption and scattering loss of light during transmission. This characteristic is crucial for daily inspections and rapid fault diagnosis, avoiding the risk of damage or seal failure that may be introduced due to frequent disassembly and reassembly.

[0089] Considering the unavoidable friction and scratches at the construction site, a final protective measure—an anti-scratch coating—is applied to the outer surface of the transparent observation window 8. This anti-scratch coating is typically a transparent inorganic silicon-based or organic fluorocarbon-based hardened coating, which is firmly adhered to the outer surface of the observation window through a special spraying or impregnation process. It increases the microhardness of the material surface, making it resistant to scratches caused by minor tool scrapes or dust wiping. Even after prolonged use, the observation window surface remains smooth and flat, maintaining its initial high light transmittance and preventing blurred vision due to surface roughening. The coating significantly extends the effective service life of the observation window, reducing the need for maintenance or replacement due to visual window failure.

[0090] The following is a specific embodiment: the internal cavity of the rigid protective box is designed to be approximately 120 mm long, 80 mm wide, and 35 mm high. This size provides ample space to accommodate two strain gauges and their terminals. Including the approximately 3 mm thick metal box walls and the protruding buffer structure on the outer perimeter, the overall maximum dimensions of the device are approximately 156 mm long, 116 mm wide, and 38 mm high. This design ensures that a cable slack loop with a diameter of approximately 30-40 mm can be reserved inside, and that a flexible sealant layer with a thickness of not less than 4.5 mm can be filled. At the same time, it provides sufficient area for eight high-performance magnetic chucks symmetrically arranged around the box, enabling the device to combine impact resistance, vibration damping, and easy maintenance in a compact structure.

[0091] The number of devices and processing scale described herein are for the purpose of simplifying the description of this utility model. Applications, modifications, and variations of this utility model will be readily apparent to those skilled in the art.

[0092] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details.

Claims

1. A strain monitoring protection device for steel plate girder incremental launching construction, characterized by, include: A rigid protective box having an installation opening for connecting to the surface of a steel plate beam; A fixing structure is provided on the rigid protective box near the mounting opening for detachably connecting the rigid protective box to the surface of the steel plate beam; wherein, the inner cavity of the rigid protective box is used to accommodate the strain gauge and its cable, the side wall of the rigid protective box is provided with a cable hole for the cable to pass through, a waterproof cable plug is provided at the cable hole, and the cable has a slack section reserved in the inner cavity; A buffer structure is provided on the outer peripheral wall of the rigid protective box; A transparent observation window is disposed on the surface of the rigid protective box away from the mounting opening; The inner cavity of the rigid protective box is filled with a flexible sealant layer around the strain gauge.

2. The strain monitoring protection device for steel plate girder incremental launching construction according to claim 1, wherein The fixing structure includes multiple magnetic chucks, which are cup-shaped permanent magnet chucks that are embedded and fixed inside the rigid protective box wall by countersunk screws, and whose adsorption working surface protrudes from the plane of the mounting opening; the multiple magnetic chucks are symmetrically distributed in a matrix around the mounting opening of the rigid protective box, and the total adsorption force provided by the magnetic chucks is greater than three times the maximum expected horizontal impact force of the entire protective device.

3. The strain monitoring protection device for steel plate girder incremental launching according to claim 2, characterized in that, A flexible wear-resistant pad is placed between the magnetic chuck and the surface of the steel plate beam. The flexible wear-resistant pad is made of polyurethane or synthetic rubber material, and its Shore A hardness is between 60° and 90°. The flexible wear-resistant pad is bonded and fixed to the adsorption working surface of the magnetic chuck by a high-strength adhesive layer, and its planar dimensions are larger than the adsorption working surface of the magnetic chuck. The free surface of the flexible wear-resistant pad is either a smooth plane or has micro-patterns that increase friction.

4. The strain monitoring protection device for steel plate girder incremental launching according to claim 1, wherein The slack section of the cable is fixed to the inner wall of the rigid protective box by a cable clip, which is a nylon cable tie, a metal spiral tube clamp, or a plastic cable clip embedded in the inner wall of the rigid protective box. The number of the wire clips is multiple, and at least the beginning, end and middle of the slack section are constrained and fixed, and the slack section is coiled into a ring with a diameter not less than 5 times the diameter of the cable. The contact surface between the cable and the wire is a smooth surface or is covered with a flexible sheath.

5. The strain monitoring protection device for steel plate girder incremental launching according to claim 1, wherein The buffer structure is a strip-shaped buffer body surrounding the outer peripheral wall of the rigid protective box. It is integrally molded from polyurethane or nitrile rubber material with a Shore A hardness of 50° to 70°. The cross-section of the strip buffer body is an outwardly convex arc or trapezoidal shape, and its outermost convex point protrudes outward by 10mm to 20mm relative to the outer peripheral wall of the rigid protective box. The strip-shaped buffer body is connected to the T-shaped groove on the outer peripheral wall of the rigid protective box by an interference fit through the T-shaped ribs pre-embedded on its inner side. The outer surface of the strip-shaped buffer is covered with a wear-resistant coating layer of reflective or fluorescent material.

6. The strain monitoring shield for use in the incremental launching of steel plate girder as recited in claim 1, wherein The rigid protective box is made of metal material, and its inner wall is fitted with a heat insulation lining. The heat insulation lining is a ceramic fiber blanket, glass fiber reinforced calcium silicate board or aerogel felt, with a thickness of 3mm to 10mm and a thermal conductivity of less than 0.05 W / (m·K). The heat insulation lining is fixed to the inner wall of the rigid protective box by high-temperature resistant adhesive, and covers at least the inner top wall opposite to the transparent observation window and the upper part of the side wall affected by heat radiation. An aluminum foil reflective layer is coated on the outer surface of the heat insulation lining, which is fixed between the heat insulation lining and the inner wall of the rigid protective box, or on the surface of the heat insulation lining facing the inner cavity.

7. The strain monitoring shield for use in the incremental launching of steel plate girder as recited in claim 1, wherein The transparent observation window and the box body of the rigid protective box are sealed by a sealing strip and fastened by quick-release bolts.

8. The strain monitoring shield for use in the incremental launching of steel plate girder as recited in claim 1, wherein The cross section of the rigid protective box is streamline elliptical.

9. The strain monitoring shield for use in the incremental launching of steel plate girder as recited in claim 1, wherein The flexible sealing glue layer is silicone sealant or polyurethane sealant, with a Shore A hardness of 20° to 40°, an elastic recovery rate of more than 90%, and a filling height in the inner cavity of not less than 1.5 times the thickness of the strain gauge.

10. The strain monitoring protection device for steel plate girder incremental launching according to claim 1, wherein, The transparent observation window is made of polycarbonate or tempered glass, with a thickness of 5mm-12mm, a light transmittance of not less than 85%, and an outer surface coated with a scratch-resistant coating.

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