CN219455025U - Measuring device for crack width change of underground masonry cultural relics - Google Patents
Measuring device for crack width change of underground masonry cultural relics Download PDFInfo
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- CN219455025U CN219455025U CN202320293144.5U CN202320293144U CN219455025U CN 219455025 U CN219455025 U CN 219455025U CN 202320293144 U CN202320293144 U CN 202320293144U CN 219455025 U CN219455025 U CN 219455025U
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Abstract
The utility model discloses a measuring device for the width change of cracks of an underground masonry cultural relic structure, which comprises a spiral compression spring, plastic gaskets and thin film flexible piezoresistive pressure sensors, wherein first surfaces of the two plastic gaskets are respectively fixed on two end surfaces of the spiral compression spring, and second surfaces of the two plastic gaskets are respectively fixed on pressure sensing surfaces of the two thin film flexible piezoresistive pressure sensors. The measuring device disclosed by the utility model converts a pressure signal into an electric signal by using the thin film flexible piezoresistive pressure sensor to output, then obtains the pressure of the spring through a detecting instrument, directly calculates the length change of the spring through Hooke's law, further obtains the change of the width of the crack of the underground masonry cultural relics, greatly improves the measuring precision of the change of the width of the crack, and can be used for long-term monitoring of the cultural relics.
Description
Technical Field
The utility model relates to a cultural relic crack measuring technology, in particular to a measuring device for the width change of a crack of an underground masonry cultural relic structure.
Background
Many underground relic structures are of masonry structures, and the relic structures, the material properties and the like are greatly deteriorated due to hundreds of years of weathering, and the environment where the underground relic is located is high in humidity, constant in temperature and rich in water, so that many cracks are generated in the relic body, and the cracks slowly and continuously develop along with time. The crack width of the underground relic structure is generally about 10mm, the change is slow, and the small-scale crack brings a plurality of difficulties for the design and selection of a measuring device. How to reasonably monitor the crack change of the underground masonry structure and provide data support for the subsequent cultural relics is a serious issue in the protection of the underground masonry type cultural relics.
Due to the characteristics of cultural relics protection, a conventional crack observation technical means needs to fix a scale or paste a marker on the cultural relics, but the mode is greatly limited due to the characteristics of the cultural relics, so that the precision is low and the persistence is poor. The detection means of the current underground relic structure cracks mainly comprise manual inspection and nondestructive detection. The manual inspection method is highly dependent on manpower and tools, and requires a measuring staff with abundant experience to detect and record positions, widths and the like of the cultural relics, but the method can damage the masonry cultural relics due to improper operation, and can cause lower detection precision and lower efficiency due to different levels of the measuring staff. The nondestructive detection is to take a photograph of the cultural relics through a camera for image recognition, but the method is greatly influenced by the accuracy of the camera and the detection environment. Therefore, aiming at the condition of low visibility in the underground space, the conventional measuring method is difficult to accurately measure and difficult to realize long-term monitoring, and a portable, high-precision and light disturbance measuring device capable of measuring the width change of the crack of the underground masonry cultural relics for a long time is necessary to design.
Disclosure of Invention
The utility model aims to: aiming at the problems, the utility model aims to provide a measuring device for the width change of the cracks of the underground masonry cultural relics.
The technical scheme is as follows: the utility model relates to a measuring device for the width change of cracks of an underground masonry cultural relic structure, which comprises a spiral compression spring, plastic gaskets and thin film flexible piezoresistive pressure sensors, wherein first surfaces of the two plastic gaskets are respectively fixed on two end surfaces of the spiral compression spring, and second surfaces of the two plastic gaskets are respectively fixed on pressure sensing surfaces of the two thin film flexible piezoresistive pressure sensors.
Further, the diameter of the thin film flexible piezoresistive pressure sensor is larger than that of the plastic gasket, and the diameter of the plastic gasket is larger than the outer diameter of the helical compression spring.
Further, the spiral compression spring is a cylindrical compression spring, the section is a metal round section, and two end faces of the spiral compression spring are tightly combined and ground flat.
Further, the surface of the plastic gasket is circular.
Further, the surface of the thin film flexible piezoresistive pressure sensor is circular.
The beneficial effects are that: compared with the prior art, the utility model has the remarkable advantages that:
1. the measuring device disclosed by the utility model converts a pressure signal into an electric signal by using the thin film flexible piezoresistive pressure sensor to output, the pressure of the spring is measured by a detecting instrument, the length change of the spring is calculated by Hooke's law, and further the change of the width of a crack of an underground masonry type cultural relic structure is obtained, so that the measuring precision of the change of the width of the crack is greatly improved, and the measuring device can be used for long-term monitoring of the cultural relics;
2. the measuring device is provided with the pressure sensors at the two ends of the device, so that the data results can be checked mutually; the average pressure value measured by the two pressure sensors is taken as a spring pressure value, so that the accuracy of a measurement result is further improved; meanwhile, the redundancy is improved, and the situation that one side of the measuring device fails and the like is prevented;
3. according to the measuring device, the ground spring end face is contacted with the plastic gasket, so that the stress area is enlarged, and the pressure intensity is reduced; the thin film flexible piezoresistive pressure sensor with the round surface is contacted with the surface of the crack of the cultural relics, so that the contact surface is enlarged, flexible contact is provided, and disturbance and damage to the crack structure in the use process of the measuring device are greatly reduced;
4. the measuring device is small in size, light and convenient, the length can be compressed at will according to cracks with different sizes, the device is easy to place, can be self-fixed in cracks of cultural relics, and can also have a good measuring effect on the positions of the cracks which are inconvenient to measure;
5. the components of the measuring device are all inner chamber finish machining, the measuring device is not influenced by human errors during measurement, the working efficiency can be improved, the labor cost is reduced, and the measuring precision is improved.
Drawings
FIG. 1 is a schematic diagram of the structure of the present utility model;
FIG. 2 is a schematic cross-sectional view of an end of a helical compression spring;
FIG. 3 is a schematic illustration of the present utility model in the measurement of a crack in a cultural relic;
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples.
Fig. 1-2 are schematic structural diagrams of a measuring device for the width change of a crack of an underground masonry type cultural relic structure according to the present embodiment, the measuring device includes a spiral compression spring 1, plastic gaskets 2 and a thin film flexible piezoresistive pressure sensor 3, wherein the number of the plastic gaskets 2 is 2, the number of the thin film flexible piezoresistive pressure sensor 3 is 2, the spiral compression spring 1 includes two end faces, first surfaces of the two plastic gaskets 2 are respectively fixed at two end faces of the spiral compression spring 1, and second surfaces of the plastic gaskets 2 are fixed at pressure sensing faces of the thin film flexible piezoresistive pressure sensor 3.
Alternatively, in the above measuring device, the first surface of the plastic spacer 2 may be fixed to the end surface of the coil compression spring 1 by means of adhesion, and the adhesion material may be selected from the epoxy resin 5. The second surface of the plastic gasket 2 can also be adhered and fixed on the pressure sensing surface of the thin film flexible piezoresistive pressure sensor 3 through epoxy resin.
Further, the diameter of the thin film flexible piezoresistive pressure sensor 3 is larger than that of the plastic gasket 2, the diameter of the plastic gasket 2 is larger than the outer diameter of the spiral compression spring 1, the contact area between the plastic gasket 2 and the spiral compression spring 1 is increased, the pressure is reduced, and disturbance to a crack contact surface is reduced while the attractiveness is ensured.
As shown in fig. 2, the spiral compression spring 1 is a cylindrical compression spring, the section is a metal circular section, and two end faces of the spiral compression spring 1 are tightly combined and ground flat, so that the perpendicularity of the spiral compression spring 1 during working is guaranteed, the supporting ring of the spiral compression spring 1 is kept in contact with the plastic gasket 2, line contact is changed into surface contact, stability and stress area are increased, and scratch of contact surfaces is avoided.
In one example, the free length of the spiral compression spring can be 10-14mm, so that the characteristic that the crack width of the underground masonry cultural relics is about 10mm is satisfied; the rigidity of the helical compression spring is 0.2-0.25N/mm, the limit load is 1.4-1.5N, and the compression force generated by the helical compression spring within the variation amplitude in operation hardly produces disturbance on the crack contact surface. The helical compression spring is always in a compressed state during the use of the measuring device, so that the normal operation and stability of the measuring device are ensured. The change amplitude of the helical compression spring in the use process of the measuring device in the embodiment is 20-40%, and the measuring device accords with the estimated degree of crack development in the masonry cultural relic structure.
The surface of the thin film flexible piezoresistive pressure sensor 3 is circular, the pressure sensing surfaces of the two thin film flexible piezoresistive pressure sensors 3 are respectively contacted with the plastic gasket 2, the pressure of the spiral compression spring 1 conducted by the plastic gasket 2 is received, the pressure signal is converted into an electric signal to be output, and the pressure is received and displayed by a monitoring instrument; the non-pressure-sensitive surfaces of the two thin film flexible piezoresistive pressure sensors 3 are respectively contacted with the two surfaces of the cultural relic crack, and damage to the surface of the cultural relic is avoided through flexible contact.
In one example, the thickness of the thin film flexible piezoresistive pressure sensor can be 1.5-2.5mm, the length of the whole measuring device is reduced, the characteristic of small crack width of the underground masonry cultural relics is met, and the selected measuring range is 0-4kP a Sensitivity ofThe method meets the requirement that pressure change is brought to the cultural relic crack in the expansion process, ensures the highest sensitivity and improves the accuracy of measurement.
The surface of the plastic gasket 2 is circular and is made of insulating materials, so that the possibility of electric conduction between the spiral compression spring 1 and the thin film flexible piezoresistive pressure sensor 3 is further reduced. The thickness of the plastic gasket 2 is usually 1-1.5mm, so that the length of the whole measuring device is reduced, and the characteristic of small crack width of the underground masonry cultural relics is met.
The measuring device in the embodiment is utilized to measure the width change of the crack of the underground masonry cultural relics, and the measuring device specifically comprises the following steps:
firstly, determining the positions of cracks of masonry relics needing to be monitored in a key way, including dangerous cracks and cracks of important parts of the structure, as shown in fig. 3, at least determining three mounting points at the cracks of the relics for placing measuring devices (three mounting points in the embodiment), wherein the distance between the measuring devices is preferably 10 cm; before installation, a certain pressure is applied to two ends of the measuring device to enable the length of the measuring device to be compressed to be suitable for the width of a target crack, then the measuring device is plugged into the crack, at the moment, the spiral compression spring 1 is always in a compressed state, and the measuring device is self-fixed in the crack of the cultural relics by utilizing the compression elasticity of the spiral compression spring 1; along with development of the crack of the cultural relics, the length of the spiral compression spring 1 is prolonged along with the crack, so that the elasticity of the spiral compression spring is changed, the spiral compression spring acts on the plastic gasket 2 and is transmitted to the thin film flexible piezoresistive pressure sensor 3, so that the pressure born by the plastic gasket is changed, and an electric signal output by the thin film flexible piezoresistive pressure sensor 3 is changed and is received by a detecting instrument to display the change of the pressure.
Under normal working conditions, taking the average value of pressure changes measured by two thin film flexible piezoresistive pressure sensors at two sides of a measuring device as a final pressure change value, and then according to Hooke's law, the length change formula of the spring is Deltal=DeltaF/k, wherein DeltaF is the pressure change value, and k is the spring stiffness, so that the elongation value of the spring, namely the change value of the crack width of the cultural relic structure, can be directly calculated according to the pressure change value.
According to the embodiment, the width change of the crack of the underground masonry type cultural relic structure is measured by using the measuring device composed of the spiral compression spring, the plastic gasket and the thin film flexible piezoresistive pressure sensor, the measuring device is arranged in the crack of the cultural relic, then the development condition of the crack of the cultural relic is converted into the length change of the spiral compression spring, the change of the elasticity of the spiral compression spring caused by the length change is converted into the electric signal output through the thin film flexible piezoresistive pressure sensor, the elasticity change of the spiral compression spring is obtained through analysis and back-pushing, and the change value of the width of the crack of the cultural relic can be calculated by using Hooke's law. In the use process of the measuring device, as the spiral compression spring is tightly combined and the end face is ground, the perpendicularity of the spiral compression spring during working is ensured, the stability of the device is improved, the stress area is increased, the pressure intensity received by a crack contact surface and a thin film flexible piezoresistive pressure sensor is reduced, and the disturbance to the crack surface of a cultural relic is reduced; the thin film flexible piezoresistive pressure sensor reduces the overall length of the device, so that the crack monitoring feasibility of the underground masonry type cultural relic structure with the characteristic of small crack width is greatly improved, and meanwhile, the high sensitivity of the thin film flexible piezoresistive pressure sensor improves the measuring accuracy.
Claims (5)
1. The measuring device for the width change of the crack of the underground masonry type cultural relics is characterized by comprising a spiral compression spring, plastic gaskets and a thin film flexible piezoresistive pressure sensor, wherein first surfaces of the two plastic gaskets are respectively fixed on two end surfaces of the spiral compression spring, and second surfaces of the two plastic gaskets are respectively fixed on pressure sensing surfaces of the two thin film flexible piezoresistive pressure sensors.
2. The measurement device of claim 1, wherein the diameter of the thin film flexible piezoresistive pressure sensor is greater than the diameter of the plastic spacer, which is greater than the outer diameter of the helical compression spring.
3. A measuring device according to claim 1 or 2, characterized in that the helical compression spring is a cylindrical compression spring, the cross section of which is a metal circular cross section, the two end faces of the helical compression spring being juxtaposed and ground flat.
4. A measuring device according to claim 1 or 2, characterized in that the surface of the plastic spacer is circular.
5. A measuring device according to claim 1 or 2, characterized in that the surface of the thin film flexible piezoresistive pressure sensor is circular.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320293144.5U CN219455025U (en) | 2023-02-23 | 2023-02-23 | Measuring device for crack width change of underground masonry cultural relics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320293144.5U CN219455025U (en) | 2023-02-23 | 2023-02-23 | Measuring device for crack width change of underground masonry cultural relics |
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| Publication Number | Publication Date |
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| CN219455025U true CN219455025U (en) | 2023-08-01 |
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| CN202320293144.5U Active CN219455025U (en) | 2023-02-23 | 2023-02-23 | Measuring device for crack width change of underground masonry cultural relics |
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| CN (1) | CN219455025U (en) |
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2023
- 2023-02-23 CN CN202320293144.5U patent/CN219455025U/en active Active
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