A large-span underground concrete beam deflection measuring device and method

Abstract

The application discloses a large-span underground concrete beam deflection measuring device and method, and relates to the technical field of civil construction, which comprises a composite layer, the composite layer is connected between concrete columns, a support rod is connected at the bottom midpoint of the composite layer, the other end of the support rod is connected with the concrete column, and the two opposite support rods form support for the middle part of the composite layer to provide a reference point whose position does not change in the process of the deflection of the concrete beam; a tension line type displacement sensor is installed at the top midpoint of the composite layer, and the composite layer is fixed to the lower surface of the concrete beam through a flexible layer. The connecting point of the composite layer and the two support rods is used as the reference point, the position of which does not change with the external environment and the deflection of the beam, the deflection of the middle span of the underground beam can be accurately measured, and the problem that the underground beam is difficult to measure by traditional methods is solved.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to a device and method for measuring the deflection of large-span underground concrete beams. Background Technology

[0002] Deflection is a crucial indicator for evaluating the safety of long-span beams, directly reflecting the overall stiffness of the beam and serving as a fundamental basis for evolutionary analysis of subsequent beam changes. Airports often employ elevated highways and subway tunnels beneath the terminal buildings to improve passenger transport efficiency. The terminal buildings require large-span underground concrete beams spanning these tunnels to transfer the weight of the superstructure. The structural safety of these underground concrete beams directly impacts the safety of the upper terminal building and the lower elevated highway and subway tunnels.

[0003] Currently, beam deflection is mainly determined by measuring the change in distance between the beam and a fixed reference point using a string-type displacement gauge. However, for underground concrete beams, the presence of backfill soil makes it difficult to place instruments, select fixed reference points, and the damp underground environment can easily cause equipment corrosion, further complicating the measurement of beam deflection. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a device and method for measuring the deflection of large-span underground concrete beams. The device uses the connection point between the composite layer and the two struts as a reference point, and its position does not change with the external environment or the beam's downward deflection. This allows for accurate measurement of the mid-span deflection of underground beams, solving the problem of the difficulty in measuring underground beams using traditional methods.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a deflection measuring device for a large-span underground concrete beam, comprising a composite layer connected between concrete columns, a strut connected at the midpoint of the bottom of the composite layer, the other end of the strut being connected to the concrete column, and two opposing struts forming a support for the middle part of the composite layer to provide a reference point whose position does not change during the deflection of the concrete beam; a wire-type displacement sensor is installed at the midpoint of the top of the composite layer, and the composite layer is fixed to the lower surface of the concrete beam by a flexible layer.

[0007] As a further implementation, the laminated layer is composed of at least two parallel steel plates.

[0008] As a further implementation, multiple stiffening ribs are provided at transverse intervals between adjacent steel plates.

[0009] As a further implementation, the pull-wire displacement sensor is connected to a signal line, which is led to the top of the concrete beam through a pre-reserved conduit.

[0010] As a further implementation, the strut is inclined between the concrete column and the composite layer.

[0011] As a further implementation, the angle between the strut and the concrete column shall not exceed 75 degrees.

[0012] As a further implementation, the flexible layer is a rubber layer, which is bonded to the bottom surface of the concrete beam using organic adhesive.

[0013] Secondly, embodiments of the present invention also provide a method for measuring the deflection of a large-span underground concrete beam, employing the aforementioned deflection measuring device, comprising:

[0014] The composite layer is fixed between the concrete columns, and the struts are tilted at a set angle and connected between the bottom midpoint of the composite layer and the concrete column;

[0015] A pull-wire displacement sensor is fixed at the middle position of the top of the composite layer, and the signal line is led to the top of the concrete beam through the reserved conduit;

[0016] The rubber layer is bonded to the concrete beams and composite slabs; and waterproofing is applied to the outside of the device.

[0017] As a further implementation method, when pouring concrete beams on site, a conduit is reserved for the lead wire of the pull-wire displacement sensor;

[0018] After the concrete strength reaches the design value, the beam span is measured, and the composite layer is fabricated according to the site dimensions; stiffening ribs are welded between the steel plates of the composite layer at set intervals.

[0019] As a further implementation, cement mortar is evenly applied to the outside of the device, then waterproof membrane is pasted on, and finally a cement mortar protective layer is applied.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) The composite layer of the present invention is connected to the concrete column on both sides, providing a reference point whose position does not change during the beam deflection process. The struts are supported at the bottom of the composite layer, which can improve the stiffness of the steel plate composite layer and ensure that the position of the reference point does not change. By using the connection point between the composite layer and the two struts as the reference point, the position does not change with the external environment and the beam deflection, and the mid-span deflection of the underground beam can be accurately measured, solving the problem that traditional methods are difficult to measure the difficulty of underground beams.

[0022] (2) The upper part of the rubber layer of the present invention is bonded to the concrete beam with organic glue, and the lower part is bonded to the steel plate composite layer with organic glue. Its main functions are moisture-proof, water-blocking, and soil-blocking. It also utilizes its easy deformation characteristics to ensure the normal deflection of the beam and prevent damage to the device during the deflection process. The composite layer is assembled by welding steel plates, and stiffening ribs are arranged at certain intervals in the composite layer to improve the rigidity of the steel plate composite layer.

[0023] (3) After the device of the present invention is assembled, the device can be protected by uniformly applying cement mortar to the outside of the device, then attaching waterproof membrane, and finally applying cement mortar protective layer. This extends the service life of the device. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a structural schematic diagram of the present invention according to one or more embodiments;

[0026] Figure 2 yes Figure 1 Schematic diagram of section 1-1;

[0027] Figure 3 yes Figure 1 Schematic diagram of section 2-2

[0028] Figure 4 yes Figure 1 Schematic diagram of section 3-3.

[0029] Among them, 1. rubber layer, 2. strut, 3. laminated layer, 4. wire-type displacement sensor, 5. signal line, and 6. stiffening rib. Detailed Implementation

[0030] Example 1:

[0031] This embodiment provides a device for measuring the deflection of large-span underground concrete beams, such as... Figure 1 As shown, it includes a flexible layer, a composite layer 3, and a wire-type displacement sensor 4. The composite layer 3 is connected between two concrete columns and its function is to provide a reference point whose position does not change during the deflection of the concrete beam. A strut 2 is connected between the bottom of the composite layer 3 and the concrete column, and the top of the composite layer 3 is fixed to the lower surface of the concrete beam through the flexible layer.

[0032] like Figure 2 and Figure 3As shown, the composite layer 3 is assembled by welding steel plates, which are parallel to each other. Adjacent steel plates are connected by multiple stiffening ribs 6 spaced apart along the transverse direction (the length of the steel plates) to improve the rigidity of the composite layer 3. The number of steel plate layers can be set according to the actual support strength, for example, two layers of steel plates can be used.

[0033] like Figure 1 As shown, two support rods 2 are connected to the middle of the bottom of the composite layer 3. One end of the support rod 2 is connected to the midpoint of the composite layer 3, and the other end is connected to a concrete column at a certain height, so that the support rod 2 is set at an angle. The connection ends of the two support rods 2 and the composite layer 3 form a support tip to improve the rigidity of the composite layer 3 and ensure that the position of the reference point does not change.

[0034] To ensure good support, the angle between strut 2 and the concrete column shall not exceed 75 degrees.

[0035] like Figure 4 As shown, the bottom of the strut 2 is fixed to the concrete column using chemical or mechanical anchors; the composite layer 3 is fixed to the concrete column using chemical or mechanical anchors; and the strut 2 is made of steel pipe.

[0036] A wire-type displacement sensor 4 is installed at the midpoint of the top of the composite layer 3. The wire-type displacement sensor 4 is connected to a signal line 5, which is led out from the top of the concrete beam through a pre-embedded conduit. Data on mid-span deflection is collected through the wire-type displacement sensor 4.

[0037] In this embodiment, the flexible layer is a rubber layer 1, which is fixed to the composite layer 3 and the concrete beam with organic adhesive. The rubber layer 1 is located on the upper surface of the composite layer 3 and on the lower surface of the concrete beam. The rubber layer 1 has the functions of moisture-proof, water-blocking and soil-blocking. It also utilizes its easy deformation characteristics to ensure the normal downward deflection of the concrete beam and to prevent damage to the device during the downward deflection of the concrete beam.

[0038] This embodiment sets up a composite layer 3 and two struts 2. The two struts 2 are supported at the midpoint of the bottom of the composite layer 3, providing a reference point whose position does not change with the external environment and beam deflection. This enables accurate measurement of the mid-span deflection of the underground beam, solving the problem of the difficulty in measuring underground beams by traditional methods. The device is easy to install and can effectively prevent the influence of soil, groundwater and other factors on the equipment, ensuring long-term measurement work.

[0039] Example 2:

[0040] This embodiment provides a method for measuring the deflection of a large-span underground concrete beam, using the deflection measuring device described in Embodiment 1, including:

[0041] Step 1: When pouring concrete for the beams and slabs on site, reserve the signal line 5 conduit for the pull-wire displacement sensor 4 for easy wiring later.

[0042] Step 2: After the concrete strength of the concrete beam reaches the design value, measure the span of the beam. Based on the site dimensions, process the composite layer 3 in the factory. The steel plates of the composite layer 3 are welded with slits. Transverse stiffening ribs 6 are welded between the steel plates of the composite layer 3 at intervals of 500mm to 1000mm.

[0043] Step 3: Install composite layer 3 on site. Use chemical anchors or mechanical anchors to fix composite layer 3 to the inside of the concrete column. During the installation process, ensure that the upper steel plate of composite layer 3 remains horizontal.

[0044] Step 4: Install and fix the support rod 2 on site. The bottom of the support rod 2 is fixed to the concrete column using chemical anchors or mechanical anchors. The top of the support rod 2 is welded to the composite layer 3 to tighten it. After installation, the angle between the support rod 2 and the concrete column shall not exceed 75 degrees.

[0045] Step 5: Install the wire-type displacement sensor 4 in the middle of the span of the concrete beam. The wire-type displacement sensor 4 is centrally located. After installation, lead the signal line 5 to the top of the slab through the reserved conduit, and use equipment to detect the sensor data. Only after confirming that the sensor is normal and error-free can the next step be carried out.

[0046] Step 6: Install rubber layer 1. Use organic adhesive to bond rubber layer 1 to the concrete beam and composite layer 3. Ensure that the organic adhesive is firmly bonded to prevent moisture from entering the device and affecting the use of the equipment.

[0047] Step 7: Apply a 1:2.5 thick layer of cement mortar evenly to the outside of the device, then attach a 4mm thick SBS waterproof membrane, and finally apply a 20mm thick 1:2.5 cement mortar protective layer; this will protect the device and extend its service life.

[0048] Step 8: The construction unit backfills the soil. When backfilling to the area of ​​support rod 2, the backfill should be evenly distributed along both sides of support rod 2 to avoid damaging support rod 2.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A device for measuring the deflection of a large-span underground concrete beam, characterized in that, It includes a composite layer connected between concrete columns. A strut is connected to the midpoint of the bottom of the composite layer, and the other end of the strut is connected to the concrete column. The two opposing struts form a support for the middle part of the composite layer to provide a reference point whose position does not change during the deflection of the concrete beam. A wire-type displacement sensor is installed at the midpoint of the top of the composite layer. The composite layer is fixed to the lower surface of the concrete beam by a flexible layer. The composite layer consists of at least two parallel steel plates; multiple stiffening ribs are arranged at transverse intervals between adjacent steel plates; the flexible layer is a rubber layer, which is bonded to the bottom surface of the concrete beam with organic adhesive.

2. The deflection measuring device for large-span underground concrete beams according to claim 1, characterized in that, The pull-wire displacement sensor is connected to a signal line, which is led to the top of the concrete beam through a pre-installed conduit.

3. The deflection measuring device for large-span underground concrete beams according to claim 1, characterized in that, The struts are inclinedly positioned between the concrete column and the composite layer.

4. The deflection measuring device for large-span underground concrete beams according to claim 3, characterized in that, The angle between the strut and the concrete column shall not exceed 75 degrees.

5. A method for measuring the deflection of a large-span underground concrete beam, characterized in that, The deflection measuring device as described in any one of claims 1-4 includes: The composite layer is fixed between the concrete columns, and the struts are tilted at a set angle and connected between the bottom midpoint of the composite layer and the concrete column; A pull-wire displacement sensor is fixed at the middle position of the top of the composite layer, and the signal line is led to the top of the concrete beam through the reserved conduit; The rubber layer is bonded to the concrete beams and composite slabs; and waterproofing is applied to the outside of the device.

6. The method for measuring the deflection of a large-span underground concrete beam according to claim 5, characterized in that, When pouring concrete beams on site, a conduit should be reserved for the lead wires of the pull-wire displacement sensor; After the concrete strength reaches the design value, the beam span is measured, and the composite layer is fabricated according to the site dimensions; stiffening ribs are welded between the steel plates of the composite layer at set intervals.

7. The method for measuring the deflection of a large-span underground concrete beam according to claim 5, characterized in that, Apply cement mortar evenly to the outside of the device, then attach the waterproof membrane, and finally apply a cement mortar protective layer.

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