A crack monitoring device for inner support of foundation pit support

Abstract

The utility model relates to the technical field of crack monitoring equipment, concretely to a foundation pit support inner support crack monitoring device, including installing the mounting support of inner support surface, the number of mounting support is two, and symmetrically sets up the crack both sides formed to inner support surface, is provided with the shrinkage monitoring subassembly and the bending moment monitoring subassembly between two mounting supports, and the shrinkage monitoring subassembly includes two ball -stud hinges, and the outer end of ball -stud hinge is detachably connected with mounting support, and the inner end of two ball -stud hinges is fixed with pressure sensor, the bending moment monitoring subassembly includes two clamping bases, and the outside of clamping base is detachably connected with mounting support, and the inside of two clamping bases is provided with elastic steel sheet, and the elastic steel sheet pastes has strain gauge. The double -channel decoupling design of shrinkage monitoring subassembly and bending moment monitoring subassembly constructs and distinguishes the crack cause, and the full -mechanical quick -release structure is combined and realizes the nondestructive reuse, solves the defect that the traditional monitoring equipment can not separate stress type and equipment can not be reused.

Description

Technical Field

[0001] This utility model mainly relates to the field of crack monitoring equipment technology, specifically a crack monitoring device for internal support of foundation pit. Background Technology

[0002] Foundation pit monitoring is an important part of foundation pit engineering construction. It refers to the observation and analysis of the changes in the soil and rock properties, support structure displacement, and surrounding environmental conditions during foundation pit excavation and underground engineering construction. The monitoring results are fed back in a timely manner to predict the deformation and stability development that will result from further construction. Based on the prediction, the degree of impact of construction on the surrounding environment is determined to guide the design and construction.

[0003] Internal support beams are an important component of foundation pit support structures. These beams include steel pipe supports and concrete supports. Cracks frequently appear in the concrete support beams during support work. To investigate the causes of surface cracks in the internal supports and to better implement appropriate crack control and repair measures, professionals in this field typically use external monitoring equipment to detect the stress state at the cracks on the surface of the internal support beams.

[0004] Current commonly used methods for monitoring the stress on internally supported beams typically involve directly attaching resistance strain gauges to the surface of the building component. The change in strain gauge resistance indicates the bending moment stress load on the component. Further research by experts in this field has shown that crack formation on the surface of internally supported beams is caused not only by bending moment stress but also by the expansion and contraction of the concrete itself due to factors such as environmental temperature. Only by accurately analyzing the true cause of the cracking can better prevention and control be achieved. However, the aforementioned method for monitoring the stress on internally supported beams cannot accurately distinguish the cause, and due to its adhesive installation method, it requires destructive removal later, making it unusable. Utility Model Content

[0005] The purpose of this invention is to provide a device for monitoring cracks in the internal support of foundation pits, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a foundation pit support internal support crack monitoring device, comprising two mounting brackets installed on the internal support surface, which are symmetrically arranged on both sides of the crack formed on the internal support surface, and a shrinkage monitoring component and a bending moment monitoring component are provided between the two mounting brackets.

[0007] The expansion and contraction monitoring component includes two ball joints, the outer ends of which are detachably connected to an adjacent mounting bracket, and a pressure sensor is fixed between the inner ends of the two ball joints.

[0008] The bending moment monitoring component includes two clamps, the outer sides of which are detachably connected to adjacent mounting brackets. An elastic steel sheet is disposed between the inner sides of the two clamps, and strain gauges are attached to the elastic steel sheet.

[0009] Preferably, the mounting bracket has an L-shaped structure, and a mounting hole is provided at the contact position with the inner support, and an expansion bolt is threadedly connected for fixation.

[0010] Furthermore, each of the mounting brackets has a screw hole at one end perpendicular to the inner support and a screw rod connected thereto. One end of the screw rod penetrates the mounting bracket and is fixedly connected to the outer end of the ball joint hinge. A nut is provided at each end of the screw rod at the connection position with the mounting bracket for double-sided reinforcement.

[0011] Furthermore, each of the mounting brackets has a square hole at one end perpendicular to the inner support, and a square hole bushing is fixedly embedded in the inner side of the bracket at the position corresponding to the square hole. A square rod is movably connected to the square hole bushing, and the inward end of the square rod is fixedly connected to the outer side of the clamp.

[0012] Preferably, the clamp is a U-shaped structure with its opening facing inward and having the same thickness as the elastic steel sheet. The two clamps cooperate to clamp both ends of the elastic steel sheet. The bottom of the clamp is also threaded with a fastening screw, which penetrates the elastic steel sheet to restrict the horizontal movement of the elastic steel sheet.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0014] This utility model provides a crack monitoring device for internal supports in foundation pits, which constructs a mechanically decoupled dual monitoring channel through a contraction and expansion monitoring component and a bending moment monitoring component. The contraction and expansion monitoring component utilizes the omnidirectional rotation characteristic of a ball-head hinge to transmit axial force. Its outer end is rigidly fixed to the mounting bracket by a screw, and its inner end is connected to a pressure sensor. The ball-head hinge adapts to crack misalignment but locks axial displacement, ensuring that the pressure sensor only captures tension / compression caused by concrete expansion and contraction. The bending moment monitoring channel adopts a sliding decoupling design. A square rod slides freely within a square-hole bushing, releasing the axial expansion and contraction of the concrete. The elastic steel sheet is held at both ends by clamps, and its U-shaped groove constraint ensures that the steel sheet only bears vertical bending moment. Strain gauges are attached to the center of the steel sheet, and the deformation purely reflects bending deformation. This device accurately measures the cause of longitudinal bending moment stress while simultaneously measuring the cause of transverse contraction and expansion stress.

[0015] 2. This utility model provides a crack monitoring device for internal supports in foundation pits. An L-shaped mounting bracket is anchored to the surface of the internal support using expansion bolts, ensuring zero contact between the monitoring components and the building structure, thus avoiding structural damage caused by traditional adhesive removal methods. The expansion / contraction monitoring component employs a screw-nut mechanical lock, with a ball-head hinge fixed to the screw. After the screw penetrates the bracket, it is clamped by double nuts. Disassembly only requires loosening the nuts. The bending moment monitoring component uses a sliding plug-in structure, with a clearance fit between the square rod and the square hole bushing. Insertion connects the components, and withdrawal separates them. The elastic steel sheet is pressed by the U-shaped groove of the clamp and screws; disassembly only requires loosening the screws. All functional modules can be quickly and safely assembled and disassembled.

[0016] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0017] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of the present invention and other related contents, and should not be considered as limitations on the present invention.

[0018] In the accompanying drawings of the instruction manual:

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0020] Figure 2 This is a schematic diagram of the top structure of the bending moment monitoring component of this utility model;

[0021] Figure label:

[0022] 1. Internal support; 2. Crack; 3. Mounting bracket; 4. Expansion bolt; 5. Screw; 6. Nut; 7. Ball joint hinge; 8. Pressure sensor; 9. Square rod; 10. Square hole bushing; 11. Clamp; 12. Fastening screw; 13. Elastic steel sheet; 14. Strain gauge. Detailed Implementation

[0023] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0024] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] like Figures 1 to 2As shown, a foundation pit support internal support crack monitoring device includes two mounting brackets 3 installed on the surface of the internal support 1, which are symmetrically arranged on both sides of the crack 2 formed on the surface of the internal support 1. A shrinkage monitoring component and a bending moment monitoring component are arranged between the two mounting brackets 3.

[0026] The expansion and contraction monitoring component includes two ball joints 7. The outer ends of the ball joints 7 are detachably connected to the adjacent mounting brackets 3. A pressure sensor 8 is fixed between the inner ends of the two ball joints 7.

[0027] The bending moment monitoring assembly includes two clamps 11. The outer side of the clamps 11 is detachably connected to the adjacent mounting bracket 3. An elastic steel sheet 13 is provided between the inner sides of the two clamps 11. A strain gauge 14 is attached to the top center of the elastic steel sheet 13.

[0028] The mounting bracket 3 has an L-shaped structure, and a mounting hole is provided at the contact position with the inner support 1, and an expansion bolt 4 is threadedly connected for fixation.

[0029] Each of the mounting brackets 3 has a screw hole at one end perpendicular to the inner support 1 and is connected to a screw rod 5. One end of the screw rod 5 penetrates the mounting bracket 3 and is fixedly connected to the outer end of the ball joint hinge 7. A nut 6 is provided at each end of the screw rod 5 at the connection position with the mounting bracket 3 for double-sided reinforcement. The preload adjustment is allowed by the double nut 6 locking mechanism to ensure that the initial preload of the pressure sensor 8 is stable and the structure is easy to disassemble and assemble.

[0030] Each of the mounting brackets 3 has a square hole at one end perpendicular to the inner support 1, and a square hole bushing 10 is fixedly embedded in the inner side of the bushing corresponding to the square hole. A square rod 9 is movably connected to the square hole bushing 10. The inward end of the square rod 9 is fixedly connected to the outer side of the clamp 11. The square rod 9 maintains its sliding freedom in the square hole bushing 10, releasing the axial displacement caused by the temperature expansion and contraction of the concrete, ensuring that the elastic steel sheet 13 only bears pure bending deformation, and avoiding axial force from interfering with the data of the strain gauge 14.

[0031] Each of the connecting seats 1 is further fitted with a fastening sleeve 4 on its outer wall. The fastening sleeve 4 is a spring steel sleeve with a height higher than that of the connecting seat 1. The inner wall of the fastening sleeve 4 is in close contact with the connecting seat 1, the front plate 2 and the side plate 3.

[0032] The clamp 11 has a U-shaped structure with its opening facing inward and the same thickness as the elastic steel sheet 13. The two clamps 11 cooperate to clamp the two ends of the elastic steel sheet 13. The bottom of the clamp 11 is also threaded with a fastening screw 12. The fastening screw 12 penetrates the elastic steel sheet 13 to restrict the horizontal movement of the elastic steel sheet 13.

[0033] The pressure sensor 8 and strain gauge 14 are connected to an external digital display or computer to transmit the monitored data to facilitate data recording and analysis.

[0034] The implementation principle of this application embodiment is as follows: In the expansion and contraction monitoring component, the outer end of the ball joint hinge 7 is fixed to the mounting bracket 3 by the screw 5, and the inner end is connected to the pressure sensor 8. During installation, the screw 5 is pre-tightened by the double nuts 6, so that the ball joint hinge 7 transmits the axial displacement caused by the expansion and contraction of concrete to the pressure sensor 8. Its universal rotation characteristic adapts to the misalignment of crack 2 but locks the axial degree of freedom, and outputs expansion and contraction force data in real time. In the bending moment monitoring component, the square rod 9 slides freely in the square hole bushing 10 to release the axial displacement. The two ends of the elastic steel sheet 13 are constrained by the clamp 11 and only deform vertically. When the inner support 1 is subjected to bending moment, the vertical misalignment on both sides of crack 2 pushes the clamp 11 to bend the elastic steel sheet 13. The strain gauge 14 attached to the steel sheet only captures the pure bending rectangular deformation data. The sudden change of pressure sensor 8 indicates the cause of expansion and contraction, and the peak value of strain gauge 14 indicates the bending moment overload. Thus, the dual data work together to achieve accurate determination of the cause of crack. During disassembly, the fastening screw 12, nut 5 and expansion bolt 4 can be removed by rotating along the thread to complete the quick and safe disassembly of each structure, which is convenient for reuse.

[0035] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from its essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A crack monitoring device for internal support in foundation pits, comprising a mounting bracket (3) installed on the surface of the internal support (1), characterized in that: The number of the mounting brackets (3) is two, and they are symmetrically arranged on both sides of the crack (2) formed on the surface of the inner support (1). A shrinkage monitoring component and a bending moment monitoring component are provided between the two mounting brackets (3). The expansion and contraction monitoring component includes two ball joints (7), the outer ends of which are detachably connected to the adjacent mounting bracket (3), and a pressure sensor (8) is fixed between the inner ends of the two ball joints (7). The bending moment monitoring assembly includes two clamps (11), the outer side of which is detachably connected to the adjacent mounting bracket (3), and an elastic steel sheet (13) is provided between the inner sides of the two clamps (11), and a strain gauge (14) is attached to the elastic steel sheet (13).

2. The device for monitoring cracks in the internal support of a foundation pit according to claim 1, characterized in that: The mounting bracket (3) has an L-shaped structure, and a mounting hole is provided at the contact position with the inner support (1) and an expansion bolt (4) is threadedly connected for fixation.

3. The device for monitoring cracks in the internal support of a foundation pit according to claim 2, characterized in that: A screw hole is opened on one end of any of the mounting brackets (3) perpendicular to the inner support (1) and a screw rod (5) is connected thereto. One end of the screw rod (5) penetrates the mounting bracket (3) and is fixedly connected to the outer end of the ball joint (7). A nut (6) is provided at both ends of the connection position between the screw rod (5) and the mounting bracket (3) for double-sided reinforcement.

4. The device for monitoring cracks in the internal support of a foundation pit according to claim 2, characterized in that: Any of the mounting brackets (3) has a square hole at one end perpendicular to the inner support (1), and a square hole bushing (10) is fixedly embedded in the inner side of the bracket corresponding to the square hole. A square rod (9) is movably connected to the square hole bushing (10), and the inward end of the square rod (9) is fixedly connected to the outer side of the clamp (11).

5. The device for monitoring cracks in the internal support of a foundation pit according to claim 1, characterized in that: The clamp (11) has a U-shaped structure with its opening facing inward and the same thickness as the elastic steel sheet (13). The two clamps (11) cooperate to clamp the two ends of the elastic steel sheet (13). The bottom of the clamp (11) is also threaded with a fastening screw (12). The fastening screw (12) penetrates the elastic steel sheet (13) to restrict the elastic steel sheet (13) from moving horizontally.

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